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Sample records for abrasive slicing technique

  1. Wire blade development for Fixed Abrasive Slicing Technique (FAST) slicing

    NASA Technical Reports Server (NTRS)

    Khattak, C. P.; Schmid, F.; Smith, M. B.

    1982-01-01

    A low cost, effective slicing method is essential to make ingot technology viable for photovoltaics in terrestrial applications. The fixed abrasive slicing technique (FAST) combines the advantages of the three commercially developed techniques. In its development stage FAST demonstrated cutting effectiveness of 10 cm and 15 cm diameter workpieces. Wire blade development is still the critical element for commercialization of FAST technology. Both impregnated and electroplated wire blades have been developed; techniques have been developed to fix diamonds only in the cutting edge of the wire. Electroplated wires show the most near term promise and this approach is emphasized. With plated wires it has been possible to control the size and shape of the electroplating, it is expected that this feature reduces kerf and prolongs the life of the wirepack.

  2. Silicon ingot casting: Heat exchanger method. Multi-wire slicing: Fixed abrasive slicing technique, phase 3

    NASA Technical Reports Server (NTRS)

    Schmid, F.; Khattak, C. P.

    1979-01-01

    In the area of ingot casting the proof of concept of heat exchanger method (HEM) was established. It was also established that HEM cast silicon yielded solar cell performance comparable to Czochralski grown material. Solar cells with conversion efficiencies of up to 15% were fabricated. It was shown that square cross-section ingots can be cast. In the area of crystal slicing, it was established that silicon can be sliced efficiently with the fixed abrasive slicing technique approach. This concept was carried forward to 10 cm diameter workpiece.

  3. Development of a fixed abrasive slicing technique (FAST) for reducing the cost of photovoltaic wafers

    SciTech Connect

    Schmid, F. )

    1991-12-01

    This report examines a wafer slicing technique developed by Crystal Systems, Inc. that reduces the cost of photovoltaic wafers. This fixed, abrasive slicing technique (FAST) uses a multiwire bladepack and a diamond-plated wirepack; water is the coolant. FAST is in the prototype production stage and reduces expendable material costs while retaining the advantages of a multiwire slurry technique. The cost analysis revealed that costs can be decreased by making more cuts per bladepack and slicing more wafers per linear inch. Researchers studied the degradation of bladepacks and increased wirepack life. 21 refs.

  4. Development of a fixed abrasive slicing technique (FAST) for reducing the cost of photovoltaic wafers. Final subcontract report, 9 January 1991--14 April 1991

    SciTech Connect

    Schmid, F.

    1991-12-01

    This report examines a wafer slicing technique developed by Crystal Systems, Inc. that reduces the cost of photovoltaic wafers. This fixed, abrasive slicing technique (FAST) uses a multiwire bladepack and a diamond-plated wirepack; water is the coolant. FAST is in the prototype production stage and reduces expendable material costs while retaining the advantages of a multiwire slurry technique. The cost analysis revealed that costs can be decreased by making more cuts per bladepack and slicing more wafers per linear inch. Researchers studied the degradation of bladepacks and increased wirepack life. 21 refs.

  5. Silicon Ingot Casting - Heat Exchanger Method (HEM). Multi-Wire Slicing - Fixed Abrasive Slicing Technique (Fast). Phase 4 Silicon Sheet Growth Development for the Large Area Sheet Task of the Low-Cost Solar Array Project

    NASA Technical Reports Server (NTRS)

    Schmid, F.

    1981-01-01

    The crystallinity of large HEM silicon ingots as a function of heat flow conditions is investigated. A balanced heat flow at the bottom of the ingot restricts spurious nucleation to the edge of the melted-back seed in contact with the crucible. Homogeneous resistivity distribution over all the ingot has been achieved. The positioning of diamonds electroplated on wirepacks used to slice silicon crystals is considered. The electroplating of diamonds on only the cutting edge is described and the improved slicing performance of these wires evaluated. An economic analysis of value added costs of HEM ingot casting and band saw sectioning indicates the projected add on cost of HEM is well below the 1986 allocation.

  6. Silicon Ingot Casting - Heat Exchanger Method Multi-wire Slicing - Fixed Abrasive Slicing Technique. Phase 3 Silicon Sheet Growth Development for the Large Area Sheet Task of the Low-cost Solar Array Project

    NASA Technical Reports Server (NTRS)

    Schmid, F.; Khattak, C. P.

    1979-01-01

    Several 20 cm diameter silicon ingots, up to 6.3 kg. were cast with good crystallinity. The graphite heat zone can be purified by heating it to high temperatures in vacuum. This is important in reducing costs and purification of large parts. Electroplated wires with 45 um synthetic diamonds and 30 um natural diamonds showed good cutting efficiency and lifetime. During slicing of a 10 cm x 10 cm workpiece, jerky motion occurred in the feed and rocking mechanisms. This problem is corrected and modifications were made to reduce the weight of the bladeheat by 50%.

  7. Silicon ingot casting - heat exchanger method (HEM); multi-wire slicing - fixed abrasive slicing technique (FAST). Phase IV. Silicon sheet growth development for the Large Area Sheet Task of the Low-Cost Solar Array Project. Quarterly progress report No. 4, October 1-December 31, 1980

    SciTech Connect

    Schmid, F.; Khattak, C.P.; Basaran, M.

    1981-02-01

    The crystallinity of large-size ingots has been studied as a function of the heat flow conditions at the bottom of the ingot. The size of the ingot has an important effect on crystallinity. The breakdown in crystallinity across the bottom has been resolved to an area in the vicinity of the melted-back seed. Generally, homogeneous resistivity distribution has been achieved all over the ingot. Electroplating of diamonds on one side of the wirepack has an important effect on slicing performance. However, diamond electroplating must be carefully controlled to have a good seat in the grooved rollers. An in-house electroplating facility is now operational. Good performance was achieved with the initial in-house electroplated wirepacks. Projected add-on cost of HEM ingot casting process has been carried out using IPEG analysis. The value that was obtained is $8.65/m/sup 2/, well below the allocation of $18.15/m/sup 2/ to meet the 1986 goal.

  8. High Resolution Laser Scanning Techniques for Rock Abrasion and Texture Analyses on Mars and Earth

    NASA Technical Reports Server (NTRS)

    Bridges, N. T.; Razdan, A.; Greeley, R.; Laity, J. E.

    2004-01-01

    Aeolian abrasion is operative in many arid locations on Earth and is probably the dominant rock erosion process in the current Martian environment. Therefore, understanding the controlling parameters and rates of aeolian abrasion provides 1) insight into the stability of rocks on planetary surfaces and the environments under which the rocks abrade, and 2) a link between ventifact (a rock abraded by windblown particles) morphology and: a) abrasion conditions, b) possible ancient environments under which the rocks were abraded, and c) rock properties. promising and we plan further investigations in the wind tunnel and field. Our intent here is to discuss the basic technique, initial results, and upcoming plans.

  9. Demonstration experience with an abrasive blasting technique for decontaminating concrete pads

    SciTech Connect

    Devgun, J.S. ); Land, R.R. ); Doane, R.W. )

    1990-01-01

    A demonstration was performed for decontaminating a radioactivity contaminated concrete pad with a portable abrasive blasting system. The system utilizes a rotating blast wheel that scours the concrete surface with metal abrasive. The metal abrasive, pulverized concrete dust, and contaminants rebound into a separator chamber. The reusable metal abrasive is recycled, and the pulverized media are removed to an integral dust collection system. The exhaust is HEPA filtered to minimize release of airborne contaminants. However, the technique had limited success in reducing contamination around the cracks and seams in the concrete where the higher activity levels of contamination were detected during the radiological survey before the cleanup. The technique can be successful and cost-effective in decontaminating large areas of low contamination; however, careful characterization and planning are necessary. 3 refs., 3 figs., 1 tabs.

  10. Comparative Evaluation of Gingival Depigmentation using Tetrafluoroethane Cryosurgery and Gingival Abrasion Technique: Two Years Follow Up

    PubMed Central

    Kumar, Santhosh; Bhat, G. Subraya; Bhat, K. Mahalinga

    2013-01-01

    Objective: A comparative evaluation of the gingival depigmentation by using Tetrafluoroethane cryosurgery and the gingival abrasion technique – 2 years of follow up. Material and Methods: Ten systemically healthy patients who were aged 18 to 36 years were selected for the study. Tetrafluoroethane was used for the cryosurgical depigmentation and the gingival abrasion technique used a coarse flame shaped bur. The presence or absence of pigmentation was tabulated, based on the GPI (Gingival Pigmentation Index). For the statistical analysis, Freidman’s test was used. Results: The keratinization was completed within a week after the application of the cryogen and about 10 days after the gingival abrasion technique was done. The statistical analysis which was done after 90th, 180th days and 2 years. The p-value which was obtained (p<.001) showed the superiority of cryosurgery over the gingival abrasion. During the follow up period, no side effects were seen for both the techniques and the improved aesthetics was maintained upto 2 years. Conclusion: The use of cryogen Tetrafluoroethane is easy, practical and inexpensive as compared to gingival abrasion, due to its high rate of recurrence. Hence, it is more acceptable to the patients and the operator. Further studies are needed to assess the long term effectiveness of the cryosurgical method of depigmentation. PMID:23543863

  11. Slice sampling technique in Bayesian extreme of gold price modelling

    NASA Astrophysics Data System (ADS)

    Rostami, Mohammad; Adam, Mohd Bakri; Ibrahim, Noor Akma; Yahya, Mohamed Hisham

    2013-09-01

    In this paper, a simulation study of Bayesian extreme values by using Markov Chain Monte Carlo via slice sampling algorithm is implemented. We compared the accuracy of slice sampling with other methods for a Gumbel model. This study revealed that slice sampling algorithm offers more accurate and closer estimates with less RMSE than other methods . Finally we successfully employed this procedure to estimate the parameters of Malaysia extreme gold price from 2000 to 2011.

  12. Kerf modelling in abrasive waterjet milling using evolutionary computation and ANOVA techniques

    NASA Astrophysics Data System (ADS)

    Alberdi, A.; Rivero, A.; Carrascal, A.; Lamikiz, A.

    2012-04-01

    Many researchers demonstrated the capability of Abrasive Waterjet (AWJ) technology for precision milling operations. However, the concurrence of several input parameters along with the stochastic nature of this technology leads to a complex process control, which requires a work focused in process modelling. This research work introduces a model to predict the kerf shape in AWJ slot milling in Aluminium 7075-T651 in terms of four important process parameters: the pressure, the abrasive flow rate, the stand-off distance and the traverse feed rate. A hybrid evolutionary approach was employed for kerf shape modelling. This technique allowed characterizing the profile through two parameters: the maximum cutting depth and the full width at half maximum. On the other hand, based on ANOVA and regression techniques, these two parameters were also modelled as a function of process parameters. Combination of both models resulted in an adequate strategy to predict the kerf shape for different machining conditions.

  13. UPb ages of zircon rims: A new analytical method using the air-abrasion technique

    USGS Publications Warehouse

    Aleinikoff, J.N.; Winegarden, D.L.; Walter, M.

    1990-01-01

    We present a new technique for directly dating, by conventional techniques, the rims of zircons. Several circumstances, such as a xenocrystic or inherited component in igneous zircon and metamorphic overgrowths on igneous cores, can result in grains with physically distinct age components. Pneumatic abrasion has been previously shown by Krogh to remove overgrowths and damaged areas of zircon, leaving more resistant and isotopically less disturbed parts available for analysis. A new abrader design, which is capable of very gently grinding only tips and interfacial edges of even needle-like grains, permits easy collection of abraded material for dating. Five examples demonstrate the utility of the "dust-collecting" technique, including two studies that compare conventional, ion microprobe and abrader data. Common Pb may be strongly concentrated in the outermost zones of many zircons and this Pb is not easily removed by leaching (even in weak HF). Thus, the benefit of removing only the outermost zones (and avoiding mixing of age components) is somewhat compromised by the much higher common Pb contents which result in less precise age determinations. A very brief abrasion to remove the high common Pb zones prior to collection of material for dating is selected. ?? 1990.

  14. Silicon Ingot Casting: Heat Exchanger Method. Multi-wire Slicing: Fixed Abrasine Slicing Technique, Phase 3

    NASA Technical Reports Server (NTRS)

    Schmid, F.; Khattak, C. P.

    1979-01-01

    Ingot casting was scaled up to 16 cm by 16 cm square cross section size and ingots weighing up to 8.1 kg were cast. The high degree of crystallinity was maintained in the large ingot. For large sizes, the nonuniformity of heat treatment causes chipping of the surface of the ingot. Progress was made in the development of a uniform graded structure in the silica crucibles. The high speed slicer blade-head weight was reduced to 37 pounds, allowing surface speeds of up to 500 feet per minute. Slicing of 10 cm diameter workpieces at these speeds increased the through-put of the machine to 0.145 mm/min.

  15. Air Abrasion

    MedlinePlus

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  16. A novel dehydration technique for carrot slices implementing ultrasound and vacuum drying methods.

    PubMed

    Chen, Zhi-Gang; Guo, Xiao-Yu; Wu, Tao

    2016-05-01

    A novel drying technique using a combination of ultrasound and vacuum dehydration was developed to shorten the drying time and improve the quality of carrot slices. Carrot slices were dried with ultrasonic vacuum (USV) drying and vacuum drying at 65 °C and 75 °C. The drying rate was significantly influenced by the drying techniques and temperatures. Compared with vacuum drying, USV drying resulted in a 41-53% decrease in the drying time. The drying time for the USV and vacuum drying techniques at 75 °C was determined to be 140 and 340 min for carrot slices, respectively. The rehydration potential, nutritional value (retention of β-carotene and ascorbic acid), color, and textural properties of USV-dried carrot slices are predominately better compared to vacuum-dried carrot slices. Moreover, lower energy consumption was used in the USV technique. The drying data (time versus moisture ratio) were successfully fitted to Wang and Singh model. PMID:26703199

  17. A technique for preparing in vitro slices of cat's visual cortex for electrophysiological experiments.

    PubMed

    Kato, H; Ogawa, T

    1981-06-01

    A technique for the preparation and in vitro maintenance of slices of neocortex from cats anesthetized with Nembutal has been described in detail. The visual cortex (posterior lateral gyrus) was cut in slices in situ using a knife consisting of two razor blades with separation of 0.7--1.0 mm. An artificially-defined medium was sprayed abundantly over the brain throughout the slicing procedures. Slices thus obtained were immediately placed between nylon meshes and incubated in a well-oxygenated medium. For recording, one of the slices was transferred to an experimental chamber in which a medium was bubbled and circulated with a gas mixture (5% CO2 in O2) introduced through a glass filter fitted at the bottom. Slices thus treated gave large evoked potentials in response to stimulation of the white matter and high-frequency injury discharges as a macroelectrode was inserted into the tissue. They also allowed stable and high-quality intracellular recordings from single neurons. PMID:7253698

  18. Dry Flowing Abrasive Decontamination Technique for Pipe Systems with Swirling Air Flow

    SciTech Connect

    Kameo, Yutaka; Nakashima, Mikio; Hirabayashi, Takakuni

    2003-10-15

    A dry abrasive decontamination method was developed for removing radioactive corrosion products from surfaces of coolant pipe systems in decommissioning of a nuclear power plant. Erosion behavior of inside surfaces of stainless and carbon steel pipes by a swirling air flow containing alumina or cast-iron grit abrasive was studied. Erosion depths of the test pipes were approximately proportional to an abrasive concentration in air and an exponent of flow rate of airstream. The experimental results indicated that the present method could keep satisfactory erosion ability of abrasives even for a large-size pipe. The present method was successfully applied to {sup 60}Co-contaminated specimens sampled from a pipe of the water cleanup system of the Japan Power Demonstration Reactor.

  19. A technique for slicing the rat cochlea around the onset of hearing.

    PubMed

    Jagger, D J; Robertson, D; Housley, G D

    2000-12-15

    The cochlea presents a considerable challenge to the study of sound transduction and auditory neurotransmission. This arises from the location of the sensory, supporting and secretory epithelia, and primary auditory neurons within a complex ossified spiral structure comprised of three separate fluid-filled chambers. We have developed a novel cochlear slice preparation, which provides access to the highly differentiated tissues while retaining structural integrity and cell viability. Our technique for slicing the cochlea and imaging tissue structure facilitates the study of peripheral auditory signaling in situ. The preparation was developed in the neonatal rat (postnatal days 4-14) and is based on the use of vibrating blade microtome slicing after perfusing the perilymphatic compartments with chilled Pluronic F127 NF, a block copolymer gel. This material is liquid when cold, and sets when warmed to room temperature, stabilizing the cochlear fluid-filled compartments and thereby supporting the cochlear partition during slicing. Slices (150-300 microm) of neonatal rat cochlea, imaged using infrared videomicroscopy, allow tight-seal voltage clamp recordings from a variety of cell types. Recordings obtained from primary auditory neurons, hair cells, supporting cells, and Reissner's membrane epithelial cells verify the viability of the tissues in the preparation. Data includes novel evidence for glutamatergic and purinergic co-transmission by primary auditory neurons. The preparation has considerable potential in a range of molecular physiological applications requiring cell-specific targeting with retention of cell connectivity. PMID:11163413

  20. "Cloud Slicing": A New Technique to Derive Upper Tropospheric Ozone from Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Chandra, Sushil; Ziemke, Jerald; Bhartia, Pawan K.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    A new technique called "cloud slicing" is introduced in this study to determine tropospheric ozone profile information. This method is unique because all previous methods incorporating satellite data were only capable of estimating the total column of ozone in the troposphere. Cloud slicing takes advantage of the opaque property of water vapor clouds to ultraviolet wavelength radiation. Measurements of above-cloud column ozone from the Nimbus 7 total ozone mapping spectrometer (TOMS) instrument are combined together with Nimbus 7 temperature humidity and infrared radiometer (THIR) cloud-top pressure data to derive ozone column amounts in the upper troposphere. In this study, tropical TOMS and THIR data for the period 1979-1984 are analyzed. Our investigation examines several case studies and illustrates the robust nature of this new technique for future satellite missions.

  1. Slicing of silicon ingots with reduced kerf. Final report (Phase II)

    SciTech Connect

    Schmid, F.; Smith, M.; Schmid, K.; Khattak, C.P.

    2001-01-04

    The Fixed Abrasive Slicing Technique (FAST) has been developed as an effective wafering technique by combining the advantages of diamond as an abrasive like internal diamond (ID), a reciprocating bladehead as in Multi-Blade Slurry (MBS) and wire slicing as in multiwire slicing (MWS) techniques. During the development stage, it was necessary to develop a slicer, bladepacks and the technique. It was recognized that high pressures were required between the diamond abrasive and the crystal to achieve effective slicing. This was achieved by rocking the workpiece to minimize the contact length. During the present work, the cutting effectiveness was enhanced by increasing the rotary speed of the crystal in the range of 2,500 to 5,000 rpm and the reciprocating rate of the bladehead to about 100 cycles/minute. The combination of high speed rotation of the crystal and FAST slicing have produced more effective slicing by increasing the cutting rate by a factor of 50 to produce multiple wafers wit h low kerf, low surface damage and high accuracy. In addition, this technique is now applicable for soft as well as very hard crystals. Based on these developments, Crystal Systems is currently commercializing FAST for slicing of a wide variety of hard and soft crystals.

  2. Abrasion-resistant antireflective coating for polycarbonate

    NASA Technical Reports Server (NTRS)

    Wydeven, T. J.

    1978-01-01

    Following plasma-polymerization technique, treatment in oxygen glow discharge further enhances abrasion resistance and transmission. Improvement in abrasion resistance was shown by measuring percentage of haze resulting from abrasion. Coating samples were analyzed for abrasion using standard fresh rubber eraser. Other tests included spectra measurements and elemental analysis with spectrometers and spectrophotometers.

  3. A comparison of different gingival depigmentation techniques: ablation by erbium:yttrium-aluminum-garnet laser and abrasion by rotary instruments

    PubMed Central

    Lee, Kwang-Myung; Lee, Dong-Yeol; Shin, Seung-Il; Kwon, Young-Hyuk; Chung, Jong-Hyuk

    2011-01-01

    Purpose The aim of this study is to compare two different gingival depigmentation techniques using an erbium:yttrium-aluminum-garnet (Er:YAG) laser and rotary instruments. Methods Two patients with melanin pigmentation of gingiva were treated with different gingival depigmentation techniques. Ablation of the gingiva by Er:YAG laser was performed on the right side, and abrasion with a rotary round bur on the opposite side. Results The patients were satisfied with the esthetically significant improvement with each method. However, some pigment still remained on the marginal gingival and papilla. The visual analog scale did not yield much difference between the two methods, with slightly more pain on the Er:YAG laser treated site. Conclusions The results of these cases suggest that ablation of the gingiva by an Er:YAG laser and abrasion with a rotary round bur is good enough to achieve esthetic satisfaction and fair wound healing without infection or severe pain. Prudent care about the gingival condition, such as the gingival thickness and degree of pigmentation along with appropriate assessment is needed in ablation by the Er:YAG laser procedure. PMID:21954425

  4. Global Free-tropospheric NO2 Abundances Derived Using a Cloud Slicing Technique from AURA OMI

    NASA Technical Reports Server (NTRS)

    Choi, S.; Joiner, J.; Choi, Y.; Duncan, B.N.; Vasilkov, A.; Krotkov, N.; Bucsela, E.J.

    2014-01-01

    We derive free-tropospheric NO2 volume mixing ratios (VMRs) by applying a cloud-slicing technique to data from the Ozone Monitoring Instrument (OMI) on the Aura satellite. In the cloud-slicing approach, the slope of the above-cloud NO2 column versus the cloud scene pressure is proportional to the NO2 VMR. In this work, we use a sample of nearby OMI pixel data from a single orbit for the linear fit. The OMI data include cloud scene pressures from the rotational-Raman algorithm and above-cloud NO2 vertical column density (VCD) (defined as the NO2 column from the cloud scene pressure to the top of the atmosphere) from a differential optical absorption spectroscopy (DOAS) algorithm. We compare OMI-derived NO2 VMRs with in situ aircraft profiles measured during the NASA Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign in 2006. The agreement is generally within the estimated uncertainties when appropriate data screening is applied. We then derive a global seasonal climatology of free-tropospheric NO2 VMR in cloudy conditions. Enhanced NO2 in the free troposphere commonly appears near polluted urban locations where NO2 produced in the boundary layer may be transported vertically out of the boundary layer and then horizontally away from the source. Signatures of lightning NO2 are also shown throughout low and middle latitude regions in summer months. A profile analysis of our cloud-slicing data indicates signatures of lightning-generated NO2 in the upper troposphere. Comparison of the climatology with simulations from the global modeling initiative (GMI) for cloudy conditions (cloud optical depth less than10) shows similarities in the spatial patterns of continental pollution outflow. However, there are also some differences in the seasonal variation of free-tropospheric NO2 VMRs near highly populated regions and in areas affected by lightning-generated NOx.

  5. "Cloud Slicing" : A New Technique to Derive Tropospheric Ozone Profile Information from Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Ziemke, J. R.; Chandra, S.; Bhartia, P. K.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    A new technique denoted cloud slicing has been developed for estimating tropospheric ozone profile information. All previous methods using satellite data were only capable of estimating the total column of ozone in the troposphere. Cloud slicing takes advantage of the opaque property of water vapor clouds to ultraviolet wavelength radiation. Measurements of above-cloud column ozone from the Nimbus 7 total ozone mapping spectrometer (TOMS) instrument are combined together with Nimbus 7 temperature humidity and infrared radiometer (THIR) cloud-top pressure data to derive ozone column amounts in the upper troposphere. In this study tropical TOMS and THIR data for the period 1979-1984 are analyzed. By combining total tropospheric column ozone (denoted TCO) measurements from the convective cloud differential (CCD) method with 100-400 hPa upper tropospheric column ozone amounts from cloud slicing, it is possible to estimate 400-1000 hPa lower tropospheric column ozone and evaluate its spatial and temporal variability. Results for both the upper and lower tropical troposphere show a year-round zonal wavenumber 1 pattern in column ozone with largest amounts in the Atlantic region (up to approx. 15 DU in the 100-400 hPa pressure band and approx. 25-30 DU in the 400-1000 hPa pressure band). Upper tropospheric ozone derived from cloud slicing shows maximum column amounts in the Atlantic region in the June-August and September-November seasons which is similar to the seasonal variability of CCD derived TCO in the region. For the lower troposphere, largest column amounts occur in the September-November season over Brazil in South America and also southern Africa. Localized increases in the tropics in lower tropospheric ozone are found over the northern region of South America around August and off the west coast of equatorial Africa in the March-May season. Time series analysis for several regions in South America and Africa show an anomalous increase in ozone in the lower

  6. Cloud Slicing: A New Technique to Derive Upper Tropospheric Ozone from Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Ziemke, J. R.; Chandra, S.; Bhartia, P. K.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    A new technique denoted cloud slicing has been developed for measuring upper tropospheric ozone. Cloud slicing takes advantage of the opaque property of water vapor clouds to ultraviolet wavelength radiation. Measurements of above-cloud column ozone from the Nimbus 7 total ozone mapping spectrometer (TOMS) instrument are combined together with Nimbus 7 temperature humidity and infrared radiometer (THIR) cloud-top pressure data to derive ozone column amounts in the upper troposphere. In this study tropical TOMS and THIR data for the period 1979-1984 are analyzed. By combining total tropospheric column ozone (denoted TCO) measurements from the convective cloud differential (CCD) method with 100-400 hPa upper tropospheric column ozone amounts from cloud slicing, it is possible to estimate 400-1000 hPa lower tropospheric column ozone and evaluate its spatial and temporal variability. Results for both the upper and lower tropical troposphere show a year-round zonal wave number 1 pattern in column ozone with largest amounts in the Atlantic region (up to 15 DU in the 100-400 hPa pressure band and around 25-30 DU in the 400-1000 hPa pressure band). Upper tropospheric ozone derived from cloud slicing shows maximum column amounts in the Atlantic region in the June-August and September-November seasons which is similar to the seasonal variability of CCD derived TCO in the region. For the lower troposphere, largest column amounts occur in the September-November season over Brazil in South America and also southern Africa. Localized increases in the tropics in lower tropospheric ozone are found over the northern region of South America around August and off the west coast of equatorial Africa in the March-May season. Time series analysis for several regions in South America and Africa show an anomalous increase in ozone in the lower troposphere around the month of March which is not observed in the upper troposphere. The eastern Pacific indicates weak seasonal variability of

  7. Multi-slice MRI with the dynamic multi-coil technique.

    PubMed

    Juchem, Christoph; Nahhass, Omar M; Nixon, Terence W; de Graaf, Robin A

    2015-11-01

    To date, spatial encoding for MRI is based on linear X, Y and Z field gradients generated by dedicated X, Y and Z wire patterns. We recently introduced the dynamic multi-coil technique (DYNAMITE) for the generation of magnetic field shapes for biomedical MR applications from a set of individually driven localized coils. The benefits for B0 magnetic field homogenization have been shown, as well as proof of principle of radial and algebraic MRI. In this study the potential of DYNAMITE MRI is explored further and the first multi-slice MRI implementation in which all gradient fields are purely DYNAMITE based is presented. The obtained image fidelity is shown to be virtually identical to that of a conventional MRI system with dedicated X, Y and Z gradient coils. Comparable image quality is a milestone towards the establishment of fully functional DYNAMITE MRI (and shim) systems. PMID:26419649

  8. Influence of Air Abrasion and Sonic Technique on Microtensile Bond Strength of One-Step Self-Etch Adhesive on Human Dentin

    PubMed Central

    Anja, Baraba; Walter, Dukić; Nicoletta, Chieffi; Marco, Ferrari; Pezelj Ribarić, Sonja; Ivana, Miletić

    2015-01-01

    The purpose of this in vitro study was to evaluate the microtensile bond strength of one-step self-etch adhesive to human dentin surface modified with air abrasion and sonic technique and to assess the morphological characteristics of the pretreated dentin surface. The occlusal enamel was removed to obtain a flat dentin surface for thirty-six human molar teeth. The teeth were randomly divided into three experimental groups (n = 12 per group), according to the pretreatment of the dentin: (1) control group, (2) air abrasion group, and (3) sonic preparation group. Microtensile bond strength test was performed on a universal testing machine. Two specimens from each experimental group were subjected to SEM examination. There was no statistically significant difference in bond strength between the three experimental groups (P > 0.05). Mean microtensile bond strength (MPa) values were 35.3 ± 12.8 for control group, 35.8 ± 13.5 for air abrasion group, and 37.7 ± 12.0 for sonic preparation group. The use of air abrasion and sonic preparation with one-step self-etch adhesive does not appear to enhance or impair microtensile bond strength in dentin. PMID:25879053

  9. Derivation of Tropospheric Column Ozone from the EPTOMS/GOES Co-Located Data Sets using the Cloud Slicing Technique

    NASA Technical Reports Server (NTRS)

    Ahn, C.; Ziemke, J. R.; Chandra, S.; Bhartia, P. K.

    2002-01-01

    A recently developed technique called cloud slicing used for deriving upper tropospheric ozone from the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) instrument combined together with temperature-humidity and infrared radiometer (THIR) is no longer applicable to the Earth Probe TOMS (EPTOMS) because EPTOMS does not have an instrument to measure cloud top temperatures. For continuing monitoring of tropospheric ozone between 200-500hPa and testing the feasibility of this technique across spacecrafts, EPTOMS data are co-located in time and space with the Geostationary Operational Environmental Satellite (GOES)-8 infrared data for 2001 and early 2002, covering most of North and South America (45S-45N and 120W-30W). The maximum column amounts for the mid-latitudinal sites of the northern hemisphere are found in the March-May season. For the mid-latitudinal sites of the southern hemisphere, the highest column amounts are found in the September-November season, although overall seasonal variability is smaller than those of the northern hemisphere. The tropical sites show the weakest seasonal variability compared to higher latitudes. The derived results for selected sites are cross validated qualitatively with the seasonality of ozonesonde observations and the results from THIR analyses over the 1979-1984 time period due to the lack of available ozonesonde measurements to study sites for 2001. These comparisons show a reasonably good agreement among THIR, ozonesonde observations, and cloud slicing-derived column ozone. With very limited co-located EPTOMS/GOES data sets, the cloud slicing technique is still viable to derive the upper tropospheric column ozone. Two new variant approaches, High-Low (HL) cloud slicing and ozone profile derivation from cloud slicing are introduced to estimate column ozone amounts using the entire cloud information in the troposphere.

  10. Performance enhancement of pre-spectrum slicing technique for wavelength conversion

    NASA Astrophysics Data System (ADS)

    Kharraz, Osayd M.; Ahmad, Harith; Mohammad, Abu Bakar B.; Forsyth, David I.; Dernaika, Mohamad; Harun, Sulaiman W.

    2015-09-01

    This paper details a proposal and successful demonstration of an ultra-narrow and very high optical signal-to-noise ratio wavelength converted channel that was generated from an efficient ultra-narrow pre-spectrum sliced probe channel via four-wave mixing in a highly non-linear fiber medium. An array of narrowband fiber Bragg grating filters acted as a discriminative component to pre-spectrum slice the probe channel from backward amplified spontaneous emission, which, in turn, induced an additional fiber Bragg grating filtering mechanism within an erbium-doped fiber medium in a saturable configuration. A resultant optical signal-to-noise ratio of more than 70 dB in the probe channel gave rise to a 40 dB optical signal-to-noise ratio in the converted channel. These outcomes indicate the proposed scheme is highly suitable for practical, cost-effective wavelength conversion in any "pre-spectrum sliced" optical communication system.

  11. Abrasion-resistant coatings for plastic surfaces

    NASA Technical Reports Server (NTRS)

    Wydeven, T.; Hollahan, J. R.

    1976-01-01

    Optically clear composition of organosilicon compounds insulates plastic surfaces and protects them from abrasion. Plasma polymerization process produces superior uniformity and clarity than previous coating techniques.

  12. Line-Integral Projection Reconstruction (LPR) with Slice Encoding Techniques: Multislice Regional Imaging in NMR Tomography.

    PubMed

    Oh, C H; Park, H W; Cho, Z H

    1984-01-01

    Line-integral projection reconstruction (LPR) in NMR imaging was found to be useful and has several advantages such as the imaging capability of objects having short T2 and compensation of phase fluctuations arising from the system instability. Although single slice LPR is found to be inefficient and poor in signal-to-noise ratio (SNR), the multislice encoded LPR method is of interest since it has a high SNR and also the capability of selected regional volume or multislice imaging. The latter, i.e., regional volume imaging capability, is a unique property of NMR imaging and offers a variety of imaging capabilities such as simultaneous multislice imaging of sagittal, transaxial, or coronal views. In this paper, we have investigated two basic forms of the multislice encoded imaging methods using LPR, i.e., Fourier and Hadamard-like encoding matrices. Applications of the methods to the experimented NMR imaging show good agreement with predicted behavior. PMID:18234626

  13. Laser initiated reactions in N{sub 2}O clusters studied by time-sliced ion velocity imaging technique

    SciTech Connect

    Honma, Kenji

    2013-07-28

    Laser initiated reactions in N{sub 2}O clusters were studied by a time-sliced velocity imaging technique. The N{sub 2}O clusters, (N{sub 2}O){sub n}, generated by supersonic expansion were irradiated by an ultraviolet laser around 204 nm to convert reactant pairs, O({sup 1}D{sub 2})-(N{sub 2}O){sub n−1}. The NO molecules formed from these reactant pairs were ionized by the same laser pulse and their velocity distribution was determined by the time-sliced velocity imaging technique. At low nozzle pressure, lower than 1.5 atm, the speed distribution in the frame moving with the clusters consists of two components. These components were ascribed to the products appeared in the backward and forward directions in the center-of-mass frame, respectively. The former consists of the vibrational ground state and the latter consists of highly vibrational excited states. At higher nozzle pressure, a single broad speed distribution became dominant for the product NO. The pressure and laser power dependences suggested that this component is attributed to the product formed in the clusters larger than dimer, (N{sub 2}O){sub n} (n ≥ 3)

  14. "Direct DICOM Slice Landmarking” A Novel Research Technique to Quantify Skeletal Changes in Orthognathic Surgery

    PubMed Central

    Almukhtar, Anas; Khambay, Balvinder; Ayoub, Ashraf; Ju, Xiangyang; Al-Hiyali, Ali; Macdonald, James; Jabar, Norhayati; Goto, Tazuko

    2015-01-01

    The limitations of the current methods of quantifying the surgical movements of facial bones inspired this study. The aim of this study was the assessment of the accuracy and reproducibility of directly landmarking of 3D DICOM images (Digital Imaging and Communications in Medicine) to quantify the changes in the jaw bones following surgery. The study was carried out on plastic skull to simulate the surgical movements of the jaw bones. Cone beam CT scans were taken at 3mm, 6mm, and 9mm maxillary advancement; together with a 2mm, 4mm, 6mm and 8mm “down graft” which in total generated 12 different positions of the maxilla for the analysis. The movements of the maxilla were calculated using two methods, the standard approach where distances between surface landmarks on the jaw bones were measured and the novel approach where measurements were taken directly from the internal structures of the corresponding 3D DICOME slices. A one sample t-test showed that there was no statistically significant difference between the two methods of measurements for the y and z directions, however, the x direction showed a significant difference. The mean difference between the two absolute measurements were 0.34±0.20mm, 0.22±0.16mm, 0.18±0.13mm in the y, z and x directions respectively. In conclusion, the direct landmarking of 3D DICOM image slices is a reliable, reproducible and informative method for assessment of the 3D skeletal changes. The method has a clear clinical application which includes the analysis of the jaw movements “orthognathic surgery” for the correction of facial deformities. PMID:26252768

  15. The measurement of abrasive particles velocities in the process of abrasive water jet generation

    NASA Astrophysics Data System (ADS)

    Zeleňák, Michal; Foldyna, Josef; Říha, Zdeněk

    2014-08-01

    An optimization of the design of the abrasive cutting head using the numerical simulation requires gathering as much information about processes occurring in the cutting head as possible. Detailed knowledge of velocities of abrasive particles in the process of abrasive water jet generation is vital for the verification of the numerical model. A method of measurement of abrasive particles at the exit of focusing tube using the FPIV technique was proposed and preliminary tests are described in the paper. Results of analysis of measured velocity fields are presented in the paper.

  16. Any Way You Slice It—A Comparison of Confocal Microscopy Techniques

    PubMed Central

    Jonkman, James

    2015-01-01

    The confocal fluorescence microscope has become a popular tool for life sciences researchers, primarily because of its ability to remove blur from outside of the focal plane of the image. Several different kinds of confocal microscopes have been developed, each with advantages and disadvantages. This article will cover the grid confocal, classic confocal laser-scanning microscope (CLSM), the resonant scanning-CLSM, and the spinning-disk confocal microscope. The way each microscope technique works, the best applications the technique is suited for, the limitations of the technique, and new developments for each technology will be presented. Researchers who have access to a range of different confocal microscopes (e.g., through a local core facility) should find this paper helpful for choosing the best confocal technology for specific imaging applications. Others with funding to purchase an instrument should find the article helpful in deciding which technology is ideal for their area of research. PMID:25802490

  17. First Look at the Upper Tropospheric Ozone Mixing Ratio from OMI Estimated using the Cloud Slicing Technique

    NASA Technical Reports Server (NTRS)

    Bhartia, Pawan K.; Ziemke, Jerry; Chandra, Sushil; Joiner, Joanna; Vassilkov, Alexandra; Taylor, Steven; Yang, Kai; Ahn, Chang-Woo

    2004-01-01

    The Cloud Slicing technique has emerged as a powerful tool for the study of ozone in the upper troposphere. In this technique one looks at the variation with cloud height of the above-cloud column ozone derived from the backscattered ultraviolet instruments, such as TOMS, to determine the ozone mixing ratio. For this technique to work properly one needs an instrument with relatively good horizontal resolution with very good signal to noise in measuring above-cloud column ozone. In addition, one needs the (radiatively) effective cloud pressure rather than the cloud-top pressure, for the ultraviolet photons received by a satellite instrument are scattered from inside the cloud rather than from the top. For this study we use data from the OMI sensor, which was recently launched on the EOS Aura satellite. OMI is a W-Visible backscattering instrument with a nadir pixel size of 13 x 24 km. The effective cloud pressure is derived from a new algorithm based on Rotational Raman Scattering and O2-O2, absorption in the 340-400 nm band of OMI.

  18. New iron-based SiC spherical composite magnetic abrasive for magnetic abrasive finishing

    NASA Astrophysics Data System (ADS)

    Zhang, Guixiang; Zhao, Yugang; Zhao, Dongbiao; Zuo, Dunwen; Yin, Fengshi

    2013-03-01

    SiC magnetic abrasive is used to polish surfaces of precise, complex parts which are hard, brittle and highly corrosion-resistant in magnetic abrasive finishing(MAF). Various techniques are employed to produce this magnetic abrasive, but few can meet production demands because they are usually time-consuming, complex with high cost, and the magnetic abrasives made by these techniques have irregular shape and low bonding strength that result in low processing efficiency and shorter service life. Therefore, an attempt is made by combining gas atomization and rapid solidification to fabricate a new iron-based SiC spherical composite magnetic abrasive. The experimental system to prepare this new magnetic abrasive is constructed according to the characteristics of gas atomization and rapid solidification process and the performance requirements of magnetic abrasive. The new iron-based SiC spherical composite magnetic abrasive is prepared successfully when the machining parameters and the composition proportion of the raw materials are controlled properly. Its morphology, microstructure, phase composition are characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD) analysis. The MAF tests on plate of mold steel S136 are carried out without grinding lubricant to assess the finishing performance and service life of this new SiC magnetic abrasive. The surface roughness( R a) of the plate worked is rapidly reduced to 0.051 μm from an initial value of 0.372 μm within 5 min. The MAF test is carried on to find that the service life of this new SiC magnetic abrasive reaches to 155 min. The results indicate that this process presented is feasible to prepare the new SiC magnetic abrasive; and compared with previous magnetic abrasives, the new SiC spherical composite magnetic abrasive has excellent finishing performance, high processing efficiency and longer service life. The presented method to fabricate magnetic abrasive through gas atomization and rapid

  19. Slice profile distortions in single slice continuously moving table MRI

    NASA Astrophysics Data System (ADS)

    Sengupta, Saikat; Smith, David S.; Welch, E. B.

    2015-03-01

    Continuously Moving Table (CMT) MRI is a rapid imaging technique that allows scanning of extended fields of view (FOVs) such as the whole-body in a single continuous scan.1 A highly efficient approach to CMT MRI is single slice imaging, where data are continuously acquired from a single axial slice at isocenter with concurrent movement of the patient table.2 However, the continuous motion of the scanner table and supply of fresh magnetization into the excited slice can introduce deviations in the slice magnetization profile. The goal of this work is to investigate and quantify the distortion in the slice profile in CMT MRI. CMT MRI with a table speed of 20 mm/s was implemented on a 3 Tesla whole-body MRI scanner, with continuous radial data acquisition. Simulations were performed to characterize the transient and steady state slice profiles and magnetization effects. Simulated slice profiles were compared to actual slice profile measurements performed in the scanner. Both simulations and experiments revealed an asymmetric slice profile characterized by a skew towards the lagging edge of the moving table, in contrast to the nominal profiles associated with scanning a stationary object. The true excited slice width (FWHM) and pitch of the acquisition was observed to be dependent on table velocity, with larger table speeds resulting in larger slice profile deviations from the nominal shape.

  20. [The application of air abrasion in dentistry].

    PubMed

    Mandinić, Zoran; Vulićević, Zoran R; Beloica, Milos; Radović, Ivana; Mandić, Jelena; Carević, Momir; Tekić, Jasmina

    2014-01-01

    One of the main objectives of contemporary dentistry is to preserve healthy tooth structure by applying techniques of noninvasive treatment. Air abrasion is a minimally invasive nonmechanical technique of tooth preparation that uses kinetic energy to remove carious tooth structure. A powerful narrow stream of moving aluminum-oxide particles hit the tooth surface and they abrade it without heat, vibration or noise. Variables that affect speed of cutting include air pressure, particle size, powder flow, tip's size, angle and distance from the tooth. It has been proposed that air abrasion can be used to diagnose early occlusal-surface lesions and treat them with minimal tooth preparation using magnifier. Reported advantages of air abrasion include reduced noise, vibration and sensitivity. Air abrasion cavity preparations have more rounded internal contours than those prepared with straight burs. This may increase the longevity of placed restorations because it reduces the incidence of fractures and a consequence of decreased internal stresses. However, air abrasion cannot be used for all patients, i.e. in cases involving severe dust allergy, asthma, chronic obstructive lung disease, recent extraction or other oral surgery, open wounds, advanced periodontal disease, recent placement of orthodontic appliances and oral abrasions, or subgingival caries removal. Many of these conditions increase the risk of air embolism in the oral soft tissues. Dust control is a challenge, and it necessitates the use of rubber dam, high-volume evacuation, protective masks and safety eyewear for both the patient and the therapist. PMID:24684041

  1. Slicing of silicon into sheet material. Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Holden, S. C.; Fleming, J. R.

    1978-01-01

    Fabrication of a prototype large capacity multiple blade slurry saw is considered. Design of the bladehead which will tension up to 1000 blades, and cut a 45 cm long silicon ingot as large as 12 cm in diameter is given. The large blade tensioning force of 270,000 kg is applied through two bolts acting on a pair of scissor toggles, significantly reducing operator set-up time. Tests with an upside-down cutting technique resulted in 100% wafering yields and the highest wafer accuracy yet experienced with MS slicing. Variations in oil and abrasives resulted only in degraded slicing results. A technique of continuous abrasive slurry separation to remove silicon debris is described.

  2. The dollars and sense of selecting abrasion-resistant materials

    SciTech Connect

    Jackson, D.

    1988-05-01

    Sliding abrasion and impact damage affect mine and plant operating costs on a month-to-month, or, in some cases, day-to-day basis. Modern technology has given us the tools necessary to fight abrasion on every front - materials and techniques that are cost-effective, long-lasting, and easy to use. An inspection of abrasion-resistant materials and processes - metals; ceramics; sprayable and trowelable compounds; polyethylene; urethane; rubber; epoxy - may well provide information that could help improve your company's balance sheet. The following is a compilation of product releases, literature, and manuals offered by manufacturers of abrasion-resistant materials.

  3. Air abrasion: an old technology reborn.

    PubMed

    Berry, E A; Eakle, W S; Summitt, J B

    1999-08-01

    Recently, air abrasion has experienced a rebirth in restorative dentistry. Originally developed in the late 1940s, the principle of air abrasion is the imparting of kinetic energy to tiny aluminum oxide particles that are projected by a stream of compressed air or gas and expelled from a small nozzle. The force generated by the relatively hard particles striking a relatively hard surface is sufficient to cut into that surface. In the last decade, more than a dozen models of air abrasion units have been introduced into the marketplace and more are on the way. Manufacturers have developed air abrasion instruments that offer a broad range of features, from small table-top units to self-contained systems with compressors, vacuums, and curing lights. The costs range dramatically--from $1,000 to $20,000 or more--depending on the complexity of the features and attachments. Manufacturers make a variety of claims to support the value of this technology to the practicing dentist. A term often used to describe one of the benefits of air abrasion is microdentistry. The claim is that smaller, less invasive tooth preparations may be accomplished using air abrasion than with a traditional bur and air turbine. This may be true in some instances, but it would certainly depend on the operator's experience and ability to visually discern fine detail. Other claims about air abrasion are that it can be used to cut into tooth structure without local anesthesia and that it should be used on all stained grooves or fissures to determine if incipient carious lesions are present. Despite the limited number of clinical studies, the popularity of air abrasion continues to grow. To gain additional insight about these claims and to see what might be on the horizon for this technology, I spoke with three highly respected educators who are recognized for their expertise in air abrasion. What they said should give the reader a better understanding of how air abrasion might augment restorative

  4. Valve for abrasive material

    DOEpatents

    Gardner, Harold S.

    1982-01-01

    A ball valve assembly for controlling the flow of abrasive particulates including an enlarged section at the bore inlet and an enlarged section at the bore outlet. A refractory ceramic annular deflector is positioned in each of the enlarged sections, substantially extending the useful life of the valve.

  5. Machining human dentin by abrasive water jet drilling.

    PubMed

    Kohorst, Philipp; Tegtmeyer, Sven; Biskup, Christian; Bach, Friedrich-Wilhelm; Stiesch, Meike

    2014-01-01

    The aim of this experimental in-vitro study was to investigate the machining of human dentin using an abrasive water jet and to evaluate the influence of different abrasives and water pressures on the removal rate. Seventy-two human teeth had been collected after extraction and randomly divided into six homogeneous groups (n=12). The teeth were processed in the area of root dentin with an industrial water jet device. Different abrasives (saccharose, sorbitol, xylitol) and water pressures (15 or 25 MPa) were used in each group. Dimensions of dentin removal were analysed using a stripe projection microscope and both drilling depth as well as volume of abrasion were recorded. Morphological analyses of the dentin cavities were performed using scanning electron microscopy (SEM). Both drilling depth and volume of abrasion were significantly influenced by the abrasive and the water pressure. Depending on these parameters, the drilling depth averaged between 142 and 378 μm; the volume of abrasion averaged between 0.07 and 0.15 mm3. Microscopic images revealed that all cavities are spherical and with clearly defined margins. Slight differences between the abrasives were found with respect to the microroughness of the surface of the cavities. The results indicate that abrasive water jet machining is a promising technique for processing human dentin. PMID:24642975

  6. Multi-wafer slicing with a fixed abrasive

    NASA Technical Reports Server (NTRS)

    Schmid, Frederick (Inventor); Khattak, Chandra P. (Inventor); Smith, Maynard B. (Inventor)

    1988-01-01

    A wafering machine having a multiplicity of wire cutting blades supported by a bladehead reciprocally moving past a workpiece supported by a holder that rocks about an axis perpendicular to the wires at a frequency less than the reciprocation of the bladehead.

  7. First estimates of global free-tropospheric NO2 abundances derived using a cloud-slicing technique applied to satellite observations from the Aura Ozone Monitoring Instrument (OMI)

    NASA Astrophysics Data System (ADS)

    Choi, S.; Joiner, J.; Choi, Y.; Duncan, B. N.; Vasilkov, A.; Krotkov, N.; Bucsela, E.

    2014-10-01

    We derive free-tropospheric NO2 volume mixing ratios (VMRs) by applying a cloud-slicing technique to data from the Ozone Monitoring Instrument (OMI) on the Aura satellite. In the cloud-slicing approach, the slope of the above-cloud NO2 column versus the cloud scene pressure is proportional to the NO2 VMR. In this work, we use a sample of nearby OMI pixel data from a single orbit for the linear fit. The OMI data include cloud scene pressures from the rotational-Raman algorithm and above-cloud NO2 vertical column density (VCD) (defined as the NO2 column from the cloud scene pressure to the top of the atmosphere) from a differential optical absorption spectroscopy (DOAS) algorithm. We compare OMI-derived NO2 VMRs with in situ aircraft profiles measured during the NASA Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign in 2006. The agreement is generally within the estimated uncertainties when appropriate data screening is applied. We then derive a global seasonal climatology of free-tropospheric NO2 VMR in cloudy conditions. Enhanced NO2 in the free troposphere commonly appears near polluted urban locations where NO2 produced in the boundary layer may be transported vertically out of the boundary layer and then horizontally away from the source. Signatures of lightning NO2 are also shown throughout low and middle latitude regions in summer months. A profile analysis of our cloud-slicing data indicates signatures of lightning-generated NO2 in the upper troposphere. Comparison of the climatology with simulations from the global modeling initiative (GMI) for cloudy conditions (cloud optical depth > 10) shows similarities in the spatial patterns of continental pollution outflow. However, there are also some differences in the seasonal variation of free-tropospheric NO2 VMRs near highly populated regions and in areas affected by lightning-generated NOx.

  8. Abrasion resistant heat pipe

    DOEpatents

    Ernst, Donald M.

    1984-10-23

    A specially constructed heat pipe for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion resistance while not substantially affecting the heat transfer characteristics of the system.

  9. Abrasion resistant heat pipe

    DOEpatents

    Ernst, D.M.

    1984-10-23

    A specially constructed heat pipe is described for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion resistance while not substantially affecting the heat transfer characteristics of the system.

  10. Global Free Tropospheric NO2 Abundances Derived Using a Cloud Slicing Technique Applied to Satellite Observations from the Aura Ozone Monitoring Instrument (OMI)

    NASA Technical Reports Server (NTRS)

    Choi, S.; Joiner, J.; Choi, Y.; Duncan, B. N.; Bucsela, E.

    2014-01-01

    We derive free-tropospheric NO2 volume mixing ratios (VMRs) and stratospheric column amounts of NO2 by applying a cloud slicing technique to data from the Ozone Monitoring Instrument (OMI) on the Aura satellite. In the cloud-slicing approach, the slope of the above-cloud NO2 column versus the cloud scene pressure is proportional to the NO2 VMR. In this work, we use a sample of nearby OMI pixel data from a single orbit for the linear fit. The OMI data include cloud scene pressures from the rotational-Raman algorithm and above-cloud NO2 vertical column density (VCD) (defined as the NO2 column from the cloud scene pressure to the top-of-the-atmosphere) from a differential optical absorption spectroscopy (DOAS) algorithm. Estimates of stratospheric column NO2 are obtained by extrapolating the linear fits to the tropopause. We compare OMI-derived NO2 VMRs with in situ aircraft profiles measured during the NASA Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign in 2006. The agreement is generally within the estimated uncertainties when appropriate data screening is applied. We then derive a global seasonal climatology of free-tropospheric NO2 VMR in cloudy conditions. Enhanced NO2 in the free troposphere commonly appears near polluted urban locations where NO2 produced in the boundary layer may be transported vertically out of the boundary layer and then horizontally away from the source. Signatures of lightning NO2 are also shown throughout low and middle latitude regions in summer months. A profile analysis of our cloud slicing data indicates signatures of uplifted and transported anthropogenic NO2 in the middle troposphere as well as lightning-generated NO2 in the upper troposphere. Comparison of the climatology with simulations from the Global Modeling Initiative (GMI) for cloudy conditions (cloud optical thicknesses > 10) shows similarities in the spatial patterns of continental pollution outflow. However, there are also some differences in

  11. Abrasion protection in process piping

    SciTech Connect

    Accetta, J.

    1996-07-01

    Process piping often is subjected to failure from abrasion or a combination of abrasion and corrosion. Abrasion is a complex phenomenon, with many factors involved to varying degrees. Hard, mineral based alumina ceramic and basalt materials are used to provide protection against abrasion in many piping systems. Successful life extension examples are presented from many different industries. Lined piping components require special attention with regard to operating conditions as well as design and engineering considerations. Economic justification involves direct cost comparisons and avoided costs.

  12. Abrasion resistant composition

    DOEpatents

    Fischer, Keith D; Barnes, Christopher A; Henderson, Stephen L

    2014-05-13

    A surface covering composition of abrasion resistant character adapted for disposition in overlying bonded relation to a metal substrate. The surface covering composition includes metal carbide particles within a metal matrix at a packing factor of not less than about 0.6. Not less than about 40 percent by weight of the metal carbide particles are characterized by an effective diameter in the range of +14-32 mesh prior to introduction to the metal matrix. Not less than about 3 percent by weight of the metal carbide particles are characterized by an effective diameter of +60 mesh prior to introduction to the metal matrix.

  13. Synthesis CNTs Particle Based Abrasive Media for Abrasive Flow Machining Process

    NASA Astrophysics Data System (ADS)

    Kumar, Sonu; Murtaza, Q.; Walia, R. S.; Dhull, S.; Tyagi, P. K.

    2016-02-01

    Abrasive flow machining (AFM) is a modem fine finishing process used for intricate and internal finishing of components or parts. It is based on flowing of viscoelastic abrasive media over the surface to be fine finished. The abrasive media is the important parameter in the AFM process because of its ability to accurately abrade the predefined area along it flow path. In this study, an attempt is made to develop a new abrasive, alumina with Carbon non tubes (CNTs) in viscoelastic medium. CNT s in house produced through chemical vapour deposition technique and characterize through TEM. Performance evaluation of the new abrasive media is carried out by increasing content of CNT s with fixed extrusion pressure, viscosity of media and media flow rate as process parameters and surface finish improvement and material removal as process responses in AFM setup. Significantly improvement has been observed in material removal and maximum improvement of 100% has been observed in the surface finish on the inner cylindrical surface of the cast iron work piece.

  14. Effects of a Destabilization Heat Treatment on the Microstructure and Abrasive Wear Behavior of High-Chromium White Cast Iron Investigated Using Different Characterization Techniques

    NASA Astrophysics Data System (ADS)

    Gasan, Hakan; Erturk, Fatih

    2013-11-01

    The hypoeutectic white cast iron was subjected to various destabilization heat treatment temperatures of 1173 K, 1273 K, and 1373 K (900 °C, 1000 °C, and 1100 °C) for 2 hours. The as-cast and destabilized specimens were characterized by optical metallography, classical direct comparison, and the Rietveld method. The volume fractions of carbides were measured by optical metallography. Moreover, the volume fractions of retained austenite and martensite were measured by the classical direct comparison method. Despite the limitations of optical metallography and the classical direct comparison method, the Rietveld method was successively and accurately applied to determine the volume fractions of all phases. In addition, the Rietveld analysis yielded certain results, such as the crystallographic properties of the phases that can be used to explain the relationship between the microstructural parameters and the wear behavior. Abrasive wear tests with different sliding speeds were carried out on the as-cast and destabilized alloys to identify the effect of microstructural parameters on the wear behavior. The results indicated that the morphologies of secondary carbides, the crystallographic properties of the phases, and the proper combination of the amount of martensite, retained austenite, and carbides were the principle parameters that affect the hardness and wear behavior of the alloy.

  15. Dermoscopy and Onychomycosis: guided nail abrasion for mycological samples*

    PubMed Central

    Bet, Diego Leonardo; dos Reis, Ana Lucia; Chiacchio, Nilton Di; Belda Junior, Walter

    2015-01-01

    Mycological examination is still the cornerstone for the diagnosis of onychomycosis for many dermatologists, but sampling technique interferes on its sensitivity and specificity. Nail abrasion may be used to reach the most proximal part of the lesion and can be easily accomplished with an electric abrasor. We suggest nail plate dermoscopy to identify the best location for localized abrasion to obtain adequate samples for mycological examination. PMID:26734877

  16. Dermoscopy and Onychomycosis: guided nail abrasion for mycological samples.

    PubMed

    Bet, Diego Leonardo; Reis, Ana Lucia dos; Di Chiacchio, Nilton; Belda Junior, Walter

    2015-01-01

    Mycological examination is still the cornerstone for the diagnosis of onychomycosis for many dermatologists, but sampling technique interferes on its sensitivity and specificity. Nail abrasion may be used to reach the most proximal part of the lesion and can be easily accomplished with an electric abrasor. We suggest nail plate dermoscopy to identify the best location for localized abrasion to obtain adequate samples for mycological examination. PMID:26734877

  17. Thick Slice and Thin Slice Teaching Evaluations

    ERIC Educational Resources Information Center

    Tom, Gail; Tong, Stephanie Tom; Hesse, Charles

    2010-01-01

    Student-based teaching evaluations are an integral component to institutions of higher education. Previous work on student-based teaching evaluations suggest that evaluations of instructors based upon "thin slice" 30-s video clips of them in the classroom correlate strongly with their end of the term "thick slice" student evaluations. This study's…

  18. Urea Biosynthesis Using Liver Slices

    ERIC Educational Resources Information Center

    Teal, A. R.

    1976-01-01

    Presented is a practical scheme to enable introductory biology students to investigate the mechanism by which urea is synthesized in the liver. The tissue-slice technique is discussed, and methods for the quantitative analysis of metabolites are presented. (Author/SL)

  19. Abrasives in snuff?

    PubMed

    Dahl, B L; Stølen, S O; Oilo, G

    1989-08-01

    The purpose of this study was to determine and calculate the inorganic contents of four brands of snuff. Visual inspection of wet snuff showed fairly large, yellow crystal-like particles. Scanning electron microscopy and X-ray dispersive (EDX) analyses were used to study both wet snuff and ashes of snuff, whereas light emission spectrography was used to determine elements in the ashes. The crystal-like particles did not dissolve in distilled water or in ethanol heated to 60 degrees C. EDX analyses showed that most elements remained in the particles after washing. The total weight percentage of inorganic material in snuff was calculated after burning dried snuff until constant weight was obtained. The ashes of snuff did not contain any crystal-like particles but consisted of a small-grained amorphous mass. The following elements were detected: Ag, Al, Ba, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, P, Pb, Si, Sr, Ti, Va, and Zr. Other elements such as rare earths were not searched for. The weight percentage of inorganic elements ranged between 12.35 +/- 0.69 and 20.95 +/- 0.81. Provided snuff is used in the same manner as chewing tobacco, and some people admit to doing so, there is a risk that its relatively high contents of inorganic material and heavily soluble salts may be conducive to excessive abrasion of teeth and restorations. PMID:2782061

  20. Conduit Coating Abrasion Testing

    NASA Technical Reports Server (NTRS)

    Sullivan, Mary K.

    2013-01-01

    During my summer internship at NASA I have been working alongside the team members of the RESTORE project. Engineers working on the RESTORE project are creating ·a device that can go into space and service satellites that no longer work due to gas shortage or other technical difficulties. In order to complete the task of refueling the satellite a hose needs to be used and covered with a material that can withstand effects of space. The conduit coating abrasion test will help the researchers figure out what type of thermal coating to use on the hose that will be refueling the satellites. The objective of the project is to determine whether or not the conduit coating will withstand the effects of space. For the RESTORE project I will help with various aspects of the testing that needed to be done in order to determine which type of conduit should be used for refueling the satellite. During my time on the project I will be assisting with wiring a relay board that connected to the test set up by soldering, configuring wires and testing for continuity. Prior to the testing I will work on creating the testing site and help write the procedure for the test. The testing will take place over a span of two weeks and lead to an informative conclusion. Working alongside various RESTORE team members I will assist with the project's documentation and records. All in all, throughout my internship at NASA I hope to learn a number of valuable skills and be a part of a hard working team of engineers.

  1. Integrating interface slicing into software engineering processes

    NASA Technical Reports Server (NTRS)

    Beck, Jon

    1993-01-01

    Interface slicing is a tool which was developed to facilitate software engineering. As previously presented, it was described in terms of its techniques and mechanisms. The integration of interface slicing into specific software engineering activities is considered by discussing a number of potential applications of interface slicing. The applications discussed specifically address the problems, issues, or concerns raised in a previous project. Because a complete interface slicer is still under development, these applications must be phrased in future tenses. Nonetheless, the interface slicing techniques which were presented can be implemented using current compiler and static analysis technology. Whether implemented as a standalone tool or as a module in an integrated development or reverse engineering environment, they require analysis no more complex than that required for current system development environments. By contrast, conventional slicing is a methodology which, while showing much promise and intuitive appeal, has yet to be fully implemented in a production language environment despite 12 years of development.

  2. Comparing the Air Abrasion Cutting Efficacy of Dentine Using a Fluoride-Containing Bioactive Glass versus an Alumina Abrasive: An In Vitro Study.

    PubMed

    Tan, Melissa H X; Hill, Robert G; Anderson, Paul

    2015-01-01

    Air abrasion as a caries removal technique is less aggressive than conventional techniques and is compatible for use with adhesive restorative materials. Alumina, while being currently the most common abrasive used for cutting, has controversial health and safety issues and no remineralisation properties. The alternative, a bioactive glass, 45S5, has the advantage of promoting hard tissue remineralisation. However, 45S5 is slow as a cutting abrasive and lacks fluoride in its formulation. The aim of this study was to compare the cutting efficacy of dentine using a customised fluoride-containing bioactive glass Na0SR (38-80 μm) versus the conventional alumina abrasive (29 μm) in an air abrasion set-up. Fluoride was incorporated into Na0SR to enhance its remineralisation properties while strontium was included to increase its radiopacity. Powder outflow rate was recorded prior to the cutting tests. Principal air abrasion cutting tests were carried out on pristine ivory dentine. The abrasion depths were quantified and compared using X-ray microtomography. Na0SR was found to create deeper cavities than alumina (p < 0.05) despite its lower powder outflow rate and predictably reduced hardness. The sharper edges of the Na0SR glass particles might improve the cutting efficiency. In conclusion, Na0SR was more efficacious than alumina for air abrasion cutting of dentine. PMID:26697067

  3. Comparing the Air Abrasion Cutting Efficacy of Dentine Using a Fluoride-Containing Bioactive Glass versus an Alumina Abrasive: An In Vitro Study

    PubMed Central

    Tan, Melissa H. X.; Hill, Robert G.; Anderson, Paul

    2015-01-01

    Air abrasion as a caries removal technique is less aggressive than conventional techniques and is compatible for use with adhesive restorative materials. Alumina, while being currently the most common abrasive used for cutting, has controversial health and safety issues and no remineralisation properties. The alternative, a bioactive glass, 45S5, has the advantage of promoting hard tissue remineralisation. However, 45S5 is slow as a cutting abrasive and lacks fluoride in its formulation. The aim of this study was to compare the cutting efficacy of dentine using a customised fluoride-containing bioactive glass Na0SR (38–80 μm) versus the conventional alumina abrasive (29 μm) in an air abrasion set-up. Fluoride was incorporated into Na0SR to enhance its remineralisation properties while strontium was included to increase its radiopacity. Powder outflow rate was recorded prior to the cutting tests. Principal air abrasion cutting tests were carried out on pristine ivory dentine. The abrasion depths were quantified and compared using X-ray microtomography. Na0SR was found to create deeper cavities than alumina (p < 0.05) despite its lower powder outflow rate and predictably reduced hardness. The sharper edges of the Na0SR glass particles might improve the cutting efficiency. In conclusion, Na0SR was more efficacious than alumina for air abrasion cutting of dentine. PMID:26697067

  4. Parametric Trace Slicing

    NASA Technical Reports Server (NTRS)

    Rosu, Grigore (Inventor); Chen, Feng (Inventor); Chen, Guo-fang; Wu, Yamei; Meredith, Patrick O. (Inventor)

    2014-01-01

    A program trace is obtained and events of the program trace are traversed. For each event identified in traversing the program trace, a trace slice of which the identified event is a part is identified based on the parameter instance of the identified event. For each trace slice of which the identified event is a part, the identified event is added to an end of a record of the trace slice. These parametric trace slices can be used in a variety of different manners, such as for monitoring, mining, and predicting.

  5. Automated Factor Slice Sampling.

    PubMed

    Tibbits, Matthew M; Groendyke, Chris; Haran, Murali; Liechty, John C

    2014-01-01

    Markov chain Monte Carlo (MCMC) algorithms offer a very general approach for sampling from arbitrary distributions. However, designing and tuning MCMC algorithms for each new distribution, can be challenging and time consuming. It is particularly difficult to create an efficient sampler when there is strong dependence among the variables in a multivariate distribution. We describe a two-pronged approach for constructing efficient, automated MCMC algorithms: (1) we propose the "factor slice sampler", a generalization of the univariate slice sampler where we treat the selection of a coordinate basis (factors) as an additional tuning parameter, and (2) we develop an approach for automatically selecting tuning parameters in order to construct an efficient factor slice sampler. In addition to automating the factor slice sampler, our tuning approach also applies to the standard univariate slice samplers. We demonstrate the efficiency and general applicability of our automated MCMC algorithm with a number of illustrative examples. PMID:24955002

  6. Automated Factor Slice Sampling

    PubMed Central

    Tibbits, Matthew M.; Groendyke, Chris; Haran, Murali; Liechty, John C.

    2013-01-01

    Markov chain Monte Carlo (MCMC) algorithms offer a very general approach for sampling from arbitrary distributions. However, designing and tuning MCMC algorithms for each new distribution, can be challenging and time consuming. It is particularly difficult to create an efficient sampler when there is strong dependence among the variables in a multivariate distribution. We describe a two-pronged approach for constructing efficient, automated MCMC algorithms: (1) we propose the “factor slice sampler”, a generalization of the univariate slice sampler where we treat the selection of a coordinate basis (factors) as an additional tuning parameter, and (2) we develop an approach for automatically selecting tuning parameters in order to construct an efficient factor slice sampler. In addition to automating the factor slice sampler, our tuning approach also applies to the standard univariate slice samplers. We demonstrate the efficiency and general applicability of our automated MCMC algorithm with a number of illustrative examples. PMID:24955002

  7. Abrasion of restorative materials by toothaste.

    PubMed

    Heath, J R; Wilson, H J

    1976-04-01

    The procedure developed in this investigation is suitable for determining the abrasion resistance of restorative materials to toothbrush/dentifrice abrasion. Ideally, a restoration should have an abrasion resistance similar to that of enamel. Of the materials tested, gold was the only one that wore slightly less than enamel, whilst amalgam wore almost twice as quickly. The silicate material and composites (excluding TD.71) wear away 2-4 times faster than enamel. TD.71 and especially the unfilled resin exhibited very high rates of abrasion. After prolonged toothbrush/dentifrice abrasion, the surfaces of gold and amalgam were considerably smoother than those of the silicate and composite materials. PMID:1066445

  8. Abrasive swivel assembly and method

    DOEpatents

    Hashish, Mohamed; Marvin, Mark

    1990-01-01

    An abrasive swivel assembly for providing a rotating, particle-laden fluid stream and, ultimately, a rotating particle-laden fluid jet is disclosed herein. This assembly includes a tubular arrangement for providing a particle-free stream of fluid, a swivel assembly for rotating a section of the tubular arrangement, and a tubular end section for introducing solid particles into the particle-free fluid stream at a point along the rotating tubular section, whereby to produce a particle-laden fluid stream. This last-mentioned stream can then be used in combination with a cooperating nozzle arrangement for providing a rotating particle-laden fluid jet. In an actual working embodiment, the fluid stream is of sufficiently high pressure so that the abrasive jet can be used as a cutting jet.

  9. Abrasive swivel assembly and method

    DOEpatents

    Hashish, Mohamed; Marvin, Mark

    1989-01-01

    An abrasive swivel assembly for providing a rotating, particle-laden fluid stream and, ultimately, a rotating particle-laden fluid jet is disclosed herein. This assembly includes a tubular arrangement for providing a particle-free stream of fluid, means for rotating a section of the tubular arrangement, and means for introducing solid particles into the particle-free fluid stream at a point along the rotating tubular section, whereby to produce a particle-laden fluid stream. This last-mentioned stream can then be used in combination with a cooperating nozzle arrangement for providing a rotating particle-laden fluid jet. In an actual working embodiment, the fluid stream is of sufficiently high pressure so that the abrasive jet can be used as a cutting jet.

  10. Slicing black hole spacetimes

    NASA Astrophysics Data System (ADS)

    Bini, Donato; Bittencourt, Eduardo; Geralico, Andrea; Jantzen, Robert T.

    2015-04-01

    A general framework is developed to investigate the properties of useful choices of stationary spacelike slicings of stationary spacetimes whose congruences of timelike orthogonal trajectories are interpreted as the world lines of an associated family of observers, the kinematical properties of which in turn may be used to geometrically characterize the original slicings. On the other hand, properties of the slicings themselves can directly characterize their utility motivated instead by other considerations like the initial value and evolution problems in the 3-plus-1 approach to general relativity. An attempt is made to categorize the various slicing conditions or "time gauges" used in the literature for the most familiar stationary spacetimes: black holes and their flat spacetime limit.

  11. Process Monitoring Evaluation and Implementation for the Wood Abrasive Machining Process

    PubMed Central

    Saloni, Daniel E.; Lemaster, Richard L.; Jackson, Steven D.

    2010-01-01

    Wood processing industries have continuously developed and improved technologies and processes to transform wood to obtain better final product quality and thus increase profits. Abrasive machining is one of the most important of these processes and therefore merits special attention and study. The objective of this work was to evaluate and demonstrate a process monitoring system for use in the abrasive machining of wood and wood based products. The system developed increases the life of the belt by detecting (using process monitoring sensors) and removing (by cleaning) the abrasive loading during the machining process. This study focused on abrasive belt machining processes and included substantial background work, which provided a solid base for understanding the behavior of the abrasive, and the different ways that the abrasive machining process can be monitored. In addition, the background research showed that abrasive belts can effectively be cleaned by the appropriate cleaning technique. The process monitoring system developed included acoustic emission sensors which tended to be sensitive to belt wear, as well as platen vibration, but not loading, and optical sensors which were sensitive to abrasive loading. PMID:22163477

  12. Ultrafast multi-slice spatiotemporally encoded MRI with slice-selective dimension segmented.

    PubMed

    Zhang, Ting; Chen, Lin; Huang, Jianpan; Li, Jing; Cai, Shuhui; Cai, Congbo; Chen, Zhong

    2016-08-01

    As a recently emerging method, spatiotemporally encoded (SPEN) magnetic resonance imaging (MRI) has a high robustness to field inhomogeneity and chemical shift effect. It has been broadened from single-slice scanning to multi-slice scanning. In this paper, a novel multi-slice SPEN MRI method was proposed. In this method, the slice-selective dimension was segmented to lower the specific absorption rate (SAR) and improve the image quality. This segmented method, dubbed SeSPEN method, was theoretically analyzed and demonstrated with phantom, lemon and in vivo rat brain experiments. The experimental results were compared with the results obtained from the spin-echo EPI, spin-echo SPEN method and multi-slice global SPEN method proposed by Frydman and coauthors (abbr. GlSPEN method). All the SPEN images were super-resolved reconstructed using deconvolution method. The results indicate that the SeSPEN method retains the advantage of SPEN MRI with respect to resistance to field inhomogeneity and can provide better signal-to-noise ratio than multi-slice GlSPEN MRI technique. The SeSPEN method has comparable SAR to the GlSPEN method while the T1 signal attenuation effect is alleviated. The proposed method will facilitate the multi-slice SPEN MRI to scan more slices within one scan with better image quality. PMID:27301072

  13. Ultrafast multi-slice spatiotemporally encoded MRI with slice-selective dimension segmented

    NASA Astrophysics Data System (ADS)

    Zhang, Ting; Chen, Lin; Huang, Jianpan; Li, Jing; Cai, Shuhui; Cai, Congbo; Chen, Zhong

    2016-08-01

    As a recently emerging method, spatiotemporally encoded (SPEN) magnetic resonance imaging (MRI) has a high robustness to field inhomogeneity and chemical shift effect. It has been broadened from single-slice scanning to multi-slice scanning. In this paper, a novel multi-slice SPEN MRI method was proposed. In this method, the slice-selective dimension was segmented to lower the specific absorption rate (SAR) and improve the image quality. This segmented method, dubbed SeSPEN method, was theoretically analyzed and demonstrated with phantom, lemon and in vivo rat brain experiments. The experimental results were compared with the results obtained from the spin-echo EPI, spin-echo SPEN method and multi-slice global SPEN method proposed by Frydman and coauthors (abbr. GlSPEN method). All the SPEN images were super-resolved reconstructed using deconvolution method. The results indicate that the SeSPEN method retains the advantage of SPEN MRI with respect to resistance to field inhomogeneity and can provide better signal-to-noise ratio than multi-slice GlSPEN MRI technique. The SeSPEN method has comparable SAR to the GlSPEN method while the T1 signal attenuation effect is alleviated. The proposed method will facilitate the multi-slice SPEN MRI to scan more slices within one scan with better image quality.

  14. Field evidence of two-phase abrasion process

    NASA Astrophysics Data System (ADS)

    Miller, K. L.; Szabo, T.; Jerolmack, D. J.; Domokos, G.

    2013-12-01

    The rounded shape of river rocks is clear evidence that abrasion due to bed load transport is a significant agent for mass loss. Its contribution to downstream fining, however, is typically assumed to be negligible - as diminution trends may be explained solely by size-selective transport. A recent theory has predicted that pebble abrasion occurs in two well separated phases: in Phase 1, an intially-polyhedral pebble rounds to the shape of an inscribed ellipsoid without any change in axis dimensions; in Phase II, axis dimensions are slowly reduced. Importantly, Phase I abrasion means that an initially-blocky pebble may lose up to half its mass without any apparent change in 'size', which is only measured as the length of a single pebble axis by most field researchers. We hypothesize that field studies have significantly underestimated the importance of abrasion because they do not quantify pebble shape, and we set out to demonstrate that two-phase abrasion occurs in a natural stream. Our study examines downstream trends in pebble size and shape along a 10-km stretch of the Rio Mameyes within the Luquillo Critical Zone observatory, where volcaniclastic cobbles and boulders are transported by bed load at slopes up to 10%. The upper reaches of the stream consist of alluviated bedrock valleys that preclude sediment storage and thus minimize size-selective transport, which allows us to isolate the effects of abrasion. The lower 5 km is an alluvial river in which size-selective transport becomes operative. We quantified the shape and size of thousands of pebbles along the profile using hand and image-based techniques. The data provide the first field validation of two-phase abrasion; in the bedrock reaches, pebbles clearly evolve toward ellipsoids without any significant change in axis dimensions (rounding), while in the lower reaches pebbles slowly reduce their axis dimensions with little or no change in roundness. Results also show that shape metrics determined from

  15. The Virtual Slice Setup

    PubMed Central

    Lytton, William W; Neymotin, Samuel A; Hines, Michael L

    2008-01-01

    In an effort to design a simulation environment that is more similar to that of neurophysiology, we introduce a virtual slice setup in the NEURON simulator. The virtual slice setup runs continuously and permits parameter changes including changes to synaptic weights and time course and to intrinsic cell properties. The virtual slice setup permits shocks to be applied at chosen locations and activity to be sampled intra- or extracellularly from chosen locations. By default, a summed population display is shown during a run to indicate the level of activity and no states are saved. Simulations can run for hours of model time, therefore it is not practical to save all of the state variables which in any case are primarily of interest at discrete times when experiments are being run: the simulation can be stopped momentarily at such times to save activity patterns. The virtual slice setup maintains an automated notebook showing shocks and parameter changes as well as user comments. We demonstrate how interaction with a continuously running simulation encourages experimental prototyping and can suggest additional dynamical features such as ligand wash-in and wash-out – alternatives to typical instantaneous parameter change. The virtual slice setup currently uses event-driven cells and runs at approximately 2 minutes/hour on a laptop. PMID:18452996

  16. Abrasive drill for resilient materials

    NASA Technical Reports Server (NTRS)

    Koch, A. J.

    1981-01-01

    Resilient materials normally present problem in obtaining accurate and uniform hole size and position. Tool is fabricated from stiff metal rod such as tungsten or carbon steel that has diameter slightly smaller than required hole. Piercing/centering point is ground on one end of rod. Rod is then plasma-sprayed (flame-sprayed) with suitable hard abrasive coating. High-speed, slow-feed operation of tool is necessary for accurate holes, and this can be done with drill press, hard drill, or similar machines.

  17. Innovative decontamination technology by abrasion in vibratory vessels

    SciTech Connect

    Fabbri, Silvio; Ilarri, Sergio

    2007-07-01

    Available in abstract form only. Full text of publication follows: The possibility of using conventional vibratory vessel technology as a decontamination technique is the motivation for the development of this project. The objective is to explore the feasibility of applying the vibratory vessel technology for decontamination of radioactively-contaminated materials such as pipes and metal structures. The research and development of this technology was granted by the U.S. Department of Energy (DOE). Abrasion processes in vibratory vessels are widely used in the manufacture of metals, ceramics, and plastics. Samples to be treated, solid abrasive media and liquid media are set up into a vessel. Erosion results from the repeated impact of the abrasive particles on the surface of the body being treated. A liquid media, generally detergents or surfactants aid the abrasive action. The amount of material removed increases with the time of treatment. The design and construction of the machine were provided by Vibro, Argentina private company. Tests with radioactively-contaminated aluminum tubes and a stainless steel bar, were performed at laboratory level. Tests showed that it is possible to clean both the external and the internal surface of contaminated tubes. Results show a decontamination factor around 10 after the first 30 minutes of the cleaning time. (authors)

  18. Multi-slice imAGe generation using intra-slice paraLLel imaging and Inter-slice shifting (MAGGULLI)

    NASA Astrophysics Data System (ADS)

    Kim, Dongchan; Seo, Hyunseok; Oh, Changheun; Han, Yeji; Park, HyunWook

    2016-02-01

    For acceleration of imaging time, multi-band imaging techniques (e.g. CAIPIRINHA) use the sensitivity differences of the multi-channel RF coils in the slice selection direction. To more effectively utilize the RF coil characteristics than the conventional multi-band imaging techniques, we propose a new imaging technique, called multi-slice image generation using intra-slice parallel imaging and inter-slice shifting (MAGGULLI). The proposed technique used an inter-slice shifting gradient in slice selection direction to make multi-slice images shift in the frequency encoding direction. Thus, aliasing caused by sub-sampling in the phase encoding direction is orthogonal to that by multi-band imaging with the inter-slice shifting, both of which are resolved by using the sensitivity information of the RF coil. Phantom and in vivo imaging experiments for the acceleration factors up to 10 demonstrate that the quality of the images reconstructed by MAGGULLI are better than that of CAIPIRINHA for high acceleration factors in the qualitative and quantitative analysis.

  19. Slice of Comet Dust

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This image illustrates one of several ways scientists have begun extracting comet particles from the Stardust spacecraft's collector. First, a particle and its track are cut out of the collector material, called aerogel, in a wedge-shaped slice called a keystone. A specialized silicon pickle fork is then used to remove the keystone from the remaining aerogel for further analysis.

  20. Ceramic-bonded abrasive grinding tools

    DOEpatents

    Holcombe, Jr., Cressie E.; Gorin, Andrew H.; Seals, Roland D.

    1994-01-01

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  1. Ceramic-bonded abrasive grinding tools

    DOEpatents

    Holcombe, C.E. Jr.; Gorin, A.H.; Seals, R.D.

    1994-11-22

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  2. Ultrasonic Abrasive Removal Of EDM Recast

    NASA Technical Reports Server (NTRS)

    Mandel, Johnny L.; Jacobson, Marlowe S.

    1990-01-01

    Ultrasonic abrasive process removes layer of recast material generated during electrical-discharge machining (EDM) of damper pocket on turbine blade. Form-fitted tool vibrated ultrasonically in damper pocket from which material removed. Vibrations activate abrasive in pocket. Amount of material removed controlled precisely.

  3. Bendable Extension For Abrasive-Jet Cleaning

    NASA Technical Reports Server (NTRS)

    Mayer, Walter

    1989-01-01

    Hard-to-reach places cleaned more easily. Extension for abrasive-jet apparatus bent to provide controlled abrasive cleaning of walls in deep cavities or other hard-to-reach places. Designed for controlled removal of penetrant inspection dyes from inside castings, extension tube also used for such general grit-blasting work as removal of scratches.

  4. Corneal abrasions associated with pepper spray exposure.

    PubMed

    Brown, L; Takeuchi, D; Challoner, K

    2000-05-01

    Pepper spray containing oleoresin capsicum is used by law enforcement and the public as a form of nonlethal deterrent. Stimulated by the identification of a case of a corneal abrasion associated with pepper spray exposure, a descriptive retrospective review of a physician-maintained log of patients presenting to a jail ward emergency area over a 3-year period was performed. The objective was to give some quantification to the frequency with which an emergency physician could expect to see corneal abrasions associated with pepper spray exposure. Of 100 cases of pepper spray exposure identified, seven patients had sustained corneal abrasions. We conclude that corneal abrasions are not rare events when patients are exposed to pepper spray and that fluorescein staining and slit lamp or Wood's lamp examination should be performed on all exposed patients in whom corneal abrasions cannot be excluded on clinical grounds. PMID:10830682

  5. Quantitative image analysis for evaluating the abrasion resistance of nanoporous silica films on glass

    NASA Astrophysics Data System (ADS)

    Nielsen, Karsten H.; Karlsson, Stefan; Limbach, Rene; Wondraczek, Lothar

    2015-12-01

    The abrasion resistance of coated glass surfaces is an important parameter for judging lifetime performance, but practical testing procedures remain overly simplistic and do often not allow for direct conclusions on real-world degradation. Here, we combine quantitative two-dimensional image analysis and mechanical abrasion into a facile tool for probing the abrasion resistance of anti-reflective (AR) coatings. We determine variations in the average coated area, during and after controlled abrasion. Through comparison with other experimental techniques, we show that this method provides a practical, rapid and versatile tool for the evaluation of the abrasion resistance of sol-gel-derived thin films on glass. The method yields informative data, which correlates with measurements of diffuse reflectance and is further supported by qualitative investigations through scanning electron microscopy. In particular, the method directly addresses degradation of coating performance, i.e., the gradual areal loss of antireflective functionality. As an exemplary subject, we studied the abrasion resistance of state-of-the-art nanoporous SiO2 thin films which were derived from 5-6 wt% aqueous solutions of potassium silicates, or from colloidal suspensions of SiO2 nanoparticles. It is shown how abrasion resistance is governed by coating density and film adhesion, defining the trade-off between optimal AR performance and acceptable mechanical performance.

  6. Quantitative image analysis for evaluating the abrasion resistance of nanoporous silica films on glass

    PubMed Central

    Nielsen, Karsten H.; Karlsson, Stefan; Limbach, Rene; Wondraczek, Lothar

    2015-01-01

    The abrasion resistance of coated glass surfaces is an important parameter for judging lifetime performance, but practical testing procedures remain overly simplistic and do often not allow for direct conclusions on real-world degradation. Here, we combine quantitative two-dimensional image analysis and mechanical abrasion into a facile tool for probing the abrasion resistance of anti-reflective (AR) coatings. We determine variations in the average coated area, during and after controlled abrasion. Through comparison with other experimental techniques, we show that this method provides a practical, rapid and versatile tool for the evaluation of the abrasion resistance of sol-gel-derived thin films on glass. The method yields informative data, which correlates with measurements of diffuse reflectance and is further supported by qualitative investigations through scanning electron microscopy. In particular, the method directly addresses degradation of coating performance, i.e., the gradual areal loss of antireflective functionality. As an exemplary subject, we studied the abrasion resistance of state-of-the-art nanoporous SiO2 thin films which were derived from 5–6 wt% aqueous solutions of potassium silicates, or from colloidal suspensions of SiO2 nanoparticles. It is shown how abrasion resistance is governed by coating density and film adhesion, defining the trade-off between optimal AR performance and acceptable mechanical performance. PMID:26656260

  7. Influence of Corrosion on the Abrasion of Cutter Steels Used in TBM Tunnelling

    NASA Astrophysics Data System (ADS)

    Espallargas, N.; Jakobsen, P. D.; Langmaack, L.; Macias, F. J.

    2015-01-01

    Abrasion on tunnel boring machine (TBM) cutters may be critical in terms of project duration and costs. Several researchers are currently studying the degradation of TBM cutter tools used for excavating hard rock, soft ground and loose soil. So far, the primary focus of this research has been directed towards abrasive wear. Abrasive wear is a very common process in TBM excavation, but with a view to the environment in which the tools are working, corrosion may also exert an influence. This paper presents a selection of techniques that can be used to evaluate the influence of corrosion on abrasion on TBM excavation tools. It also presents the influence of corrosion on abrasive wear for some initial tests, with constant steel and geomaterial and varying properties of the excavation fluids (soil conditioners, anti-abrasion additives and water). The results indicate that the chloride content in the water media greatly influences the amount of wear, providing evidence of the influence of corrosion on the abrasion of the cutting tools. The presence of conditioning additives tailored to specific rock or soil conditions reduces wear. However, when chloride is present in the water, the additives minimise wear rates but fail to suppress corrosion of the cutting tools.

  8. Portable Device Slices Thermoplastic Prepregs

    NASA Technical Reports Server (NTRS)

    Taylor, Beverly A.; Boston, Morton W.; Wilson, Maywood L.

    1993-01-01

    Prepreg slitter designed to slit various widths rapidly by use of slicing bar holding several blades, each capable of slicing strip of preset width in single pass. Produces material evenly sliced and does not contain jagged edges. Used for various applications in such batch processes involving composite materials as press molding and autoclaving, and in such continuous processes as pultrusion. Useful to all manufacturers of thermoplastic composites, and in slicing B-staged thermoset composites.

  9. Analysis of ancient-river systems by 3D seismic time-slice technique: A case study in northeast Malay Basin, offshore Terengganu, Malaysia

    SciTech Connect

    Sulaiman, Noorzamzarina; Hamzah, Umar; Samsudin, Abdul Rahim

    2014-09-03

    Fluvial sandstones constitute one of the major clastic petroleum reservoir types in many sedimentary basins around the world. This study is based on the analysis of high-resolution, shallow (seabed to 500 m depth) 3D seismic data which generated three-dimensional (3D) time slices that provide exceptional imaging of the geometry, dimension and temporal and spatial distribution of fluvial channels. The study area is in the northeast of Malay Basin about 280 km to the east of Terengganu offshore. The Malay Basin comprises a thick (> 8 km), rift to post-rift Oligo-Miocene to Pliocene basin-fill. The youngest (Miocene to Pliocene), post-rift succession is dominated by a thick (1–5 km), cyclic succession of coastal plain and coastal deposits, which accumulated in a humid-tropical climatic setting. This study focuses on the Pleistocene to Recent (500 m thick) succession, which comprises a range of seismic facies analysis of the two-dimensional (2D) seismic sections, mainly reflecting changes in fluvial channel style and river architecture. The succession has been divided into four seismic units (Unit S1-S4), bounded by basin-wide strata surfaces. Two types of boundaries have been identified: 1) a boundary that is defined by a regionally-extensive erosion surface at the base of a prominent incised valley (S3 and S4); 2) a sequence boundary that is defined by more weakly-incised, straight and low-sinuosity channels which is interpreted as low-stand alluvial bypass channel systems (S1 and S2). Each unit displays a predictable vertical change of the channel pattern and scale, with wide low-sinuosity channels at the base passing gradationally upwards into narrow high-sinuosity channels at the top. The wide variation in channel style and size is interpreted to be controlled mainly by the sea-level fluctuations on the widely flat Sunda land Platform.

  10. Flash lamp light slicing

    NASA Astrophysics Data System (ADS)

    Saber, A. J.; Abdel-Wahab, T.; Georgallis, M.

    A light slicing system using a short-arc-length high-power flashlamp as the source is discussed, with application to the observation of fluid phenomena such as gas discharge and fuel injection into engines. The geometrical optics of the method, in addition to the attenuation of luminous intensity in the system, is considered, and varying the relative radius of curvature of the cylindrical lens with respect to the width of the laser beam is shown to change the extension of the light sheet lamina. Light slice system generation using CAD is discussed, and experimental results of the observation of pulsed gas discharges in a small scale valve system designed to simulate large-scale dispersion and mixing of gases in air are reported.

  11. Robust reflective pupil slicing technology

    NASA Astrophysics Data System (ADS)

    Meade, Jeffrey T.; Behr, Bradford B.; Cenko, Andrew T.; Hajian, Arsen R.

    2014-07-01

    applicable to multi-fiber spectrometers to achieve similar enhancement. HTVS also provides the ability to anamorphically "stretch" the slit image in long-slit spectrometers, allowing the instrument designer to optimize the plate scale in the dispersion axis and cross-dispersion axes independently without sacrificing spatial information. This allows users to widen the input slit, with the associated gain of throughput and loss of spatial selectivity, while maintaining the spectral resolution of the spectrometer system. This "stretching" places increased requirements on detector focal plane height, as with image slicing techniques, but provides additional degrees of freedom to instrument designers to build the best possible spectrometer systems. We discuss the details of this technology for an astronomical context, covering the applicability from small telescope mounted spectrometers through long-slit imagers and radial-velocity engines. This powerful tool provides additional degrees of freedom when designing a spectrometer, enabling instrument designers to further optimize systems for the required scientific goals.

  12. Nanometric Finishing on Biomedical Implants by Abrasive Flow Finishing

    NASA Astrophysics Data System (ADS)

    Subramanian, Kavithaa Thirumalai; Balashanmugam, Natchimuthu; Shashi Kumar, Panaghra Veeraiah

    2016-01-01

    Abrasive flow finishing (AFF) is a non-conventional finishing technique that offers better accuracy, efficiency, consistency, economy in finishing of complex/difficult to machine materials/components and provides the possibility of effective automation as aspired by the manufacturing sector. The present study describes the finishing of a hip joint made of ASTM grade Co-Cr alloy by Abrasive Flow Machining (AFM) process. The major input parameters of the AFF process were optimized for achieving nanometric finishing of the component. The roughness average (Ra) values were recorded during experimentation using surface roughness tester and the results are discussed in detail. The surface finished hip joints were characterized using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and residual stress analysis using X-Ray Diffraction (XRD). The discussion lays emphasis on the significance, efficacy and versatile nature of the AFF process in finishing of bio-medical implants.

  13. Three-Body Abrasion Testing Using Lunar Dust Simulants to Evaluate Surface System Materials

    NASA Technical Reports Server (NTRS)

    Kobrick, Ryan L.; Budinski, Kenneth G.; Street, Kenneth W., Jr.; Klaus, David M.

    2010-01-01

    Numerous unexpected operational issues relating to the abrasive nature of lunar dust, such as scratched visors and spacesuit pressure seal leaks, were encountered during the Apollo missions. To avoid reoccurrence of these unexpected detrimental equipment problems on future missions to the Moon, a series of two- and three-body abrasion tests were developed and conducted in order to begin rigorously characterizing the effect of lunar dust abrasiveness on candidate surface system materials. Two-body scratch tests were initially performed to examine fundamental interactions of a single particle on a flat surface. These simple and robust tests were used to establish standardized measurement techniques for quantifying controlled volumetric wear. Subsequent efforts described in the paper involved three-body abrasion testing designed to be more representative of actual lunar interactions. For these tests, a new tribotester was developed to expose samples to a variety of industrial abrasives and lunar simulants. The work discussed in this paper describes the three-body hardware setup consisting of a rotating rubber wheel that applies a load on a specimen as a loose abrasive is fed into the system. The test methodology is based on ASTM International (ASTM) B611, except it does not mix water with the abrasive. All tests were run under identical conditions. Abraded material specimens included poly(methyl methacrylate) (PMMA), hardened 1045 steel, 6061-T6 aluminum (Al) and 1018 steel. Abrasives included lunar mare simulant JSC- 1A-F (nominal size distribution), sieved JSC-1A-F (<25 m particle diameter), lunar highland simulant NU-LHT-2M, alumina (average diameter of 50 m used per ASTM G76), and silica (50/70 mesh used per ASTM G65). The measured mass loss from each specimen was converted using standard densities to determine total wear volume in cm3. Abrasion was dominated by the alumina and the simulants were only similar to the silica (i.e., sand) on the softer materials of

  14. The abrasion and impact-abrasion behavior of austempered ductile irons

    SciTech Connect

    Hawk, Jeffrey A.; Dogan, Omer N.; Lerner, Y.S.

    1998-01-01

    Austempering of ductile irons has led to a new class of irons, Austempered Ductile Irons (ADIs), with improved mechanical strength and fracture toughness lacking in gray cast irons. Laboratory wear tests have been used to evaluate the abrasive and impact-abrasive wear behavior of a suite of ADIs. The use of high-stress, two-body abrasion, low-stress, three-body abrasion, and impact-abrasion tests provides a clear picture of the abrasive wear behavior of the ADIs and the mechanisms of material removal. When combined with hardness measurements, fracture toughness and a knowledge of the microstructure of the ADIs, the overall performance can be assessed relative to more wear resistant materials such as martensitic steels and high-chromium white cast irons

  15. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories. (a) Identification. An abrasive device and accessories is a device constructed of various abrasives... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Abrasive device and accessories. 872.6010...

  16. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories. (a) Identification. An abrasive device and accessories is a device constructed of various abrasives... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Abrasive device and accessories. 872.6010...

  17. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories. (a) Identification. An abrasive device and accessories is a device constructed of various abrasives... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Abrasive device and accessories. 872.6010...

  18. Multilayer PDMS microfluidic chamber for controlling brain slice microenvironment

    PubMed Central

    Blake, A. J.; Pearce, T. M.; Rao, N. S.; Johnson, S. M.; Williams, J. C.

    2008-01-01

    A novel three-layer microfluidic polydimethylsiloxane (PDMS) device was constructed with two fluid chambers that holds a brain slice in place with microposts while maintaining laminar perfusate flow above and below the slice. Our fabrication technique permits rapid production of PDMS layers that can be applied to brain slices of different shapes and sizes. In this study, the device was designed to fit the shape and thickness (530-700 μm) of a medullary brain slice taken from P0-P4 neonatal rats. Medullary slices in this chamber spontaneously produced rhythmic, respiratory-related motor output for up to 3 h, thereby demonstrating that brain slice viability was maintained for prolonged periods. This design is unique in that it achieves independent control of fluids through multiple channels in two separate fluid chambers. The laminar flow exhibited by the microfluidic chamber allows controlled solutions to target specific areas of the brain slice based on the input flow rates. To demonstrate this capability, a stream of Na+-free solution was focused on one half of a medullary slice to abolish spontaneous neural activity in only that half of the brain slice, while the other half remained active. We also demonstrated that flow of different solutions can be focused over the midline of the brain slice. The multilayer brain slice chamber design can integrate several traditional types of electrophysiology tools that are commonly used to measure neurophysiological properties of brain slices. Thus, this new microfluidic chamber is advantageous for experiments that involve controlled drug or solution delivery at high spatiotemporal resolution. PMID:17594002

  19. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  20. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  1. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  2. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  3. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  4. Abrasion by aeolian particles: Earth and Mars

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Marshall, J. R.; White, B. R.; Pollack, J. B.; Marshall, J.; Krinsley, D.

    1984-01-01

    Estimation of the rate of aeolian abrasion of rocks on Mars requires knowledge of: (1) particle flux, (2) susceptibilities to abrasion of various rocks, and (3) wind frequencies on Mars. Fluxes and susceptibilities for a wide range of conditions were obtained in the laboratory and combined with wind data from the Viking meteorology experiment. Assuming an abundant supply of sand-sized particles, estimated rates range up to 2.1 x 10 to the minus 2 power cm of abrasion per year in the vicinity of Viking Lander 1. This rate is orders of magnitude too great to be in agreement with the inferred age of the surface based on models of impact crater flux. The discrepancy in the estimated rate of abrasion and the presumed old age of the surface cannot be explained easily by changes in climate or exhumation of ancient surfaces. The primary reason is thought to be related to the agents of abrasion. At least some sand-sized (approx. 100 micrometers) grains appear to be present, as inferred from both lander and orbiter observations. High rates of abrasion occur for all experimental cases involving sands of quartz, basalt, or ash. However, previous studies have shown that sand is quickly comminuted to silt- and clay-sized grains in the martian aeolian regime. Experiments also show that these fine grains are electrostatically charged and bond together as sand-sized aggregates. Laboratory simulations of wind abrasion involving aggregates show that at impact velocities capable of destroying sand, aggregates from a protective veneer on the target surface and can give rise to extremely low abrasion rates.

  5. Computed tomography to quantify tooth abrasion

    NASA Astrophysics Data System (ADS)

    Kofmehl, Lukas; Schulz, Georg; Deyhle, Hans; Filippi, Andreas; Hotz, Gerhard; Berndt-Dagassan, Dorothea; Kramis, Simon; Beckmann, Felix; Müller, Bert

    2010-09-01

    Cone-beam computed tomography, also termed digital volume tomography, has become a standard technique in dentistry, allowing for fast 3D jaw imaging including denture at moderate spatial resolution. More detailed X-ray images of restricted volumes for post-mortem studies in dental anthropology are obtained by means of micro computed tomography. The present study evaluates the impact of the pipe smoking wear on teeth morphology comparing the abraded tooth with its contra-lateral counterpart. A set of 60 teeth, loose or anchored in the jaw, from 12 dentitions have been analyzed. After the two contra-lateral teeth were scanned, one dataset has been mirrored before the two datasets were registered using affine and rigid registration algorithms. Rigid registration provides three translational and three rotational parameters to maximize the overlap of two rigid bodies. For the affine registration, three scaling factors are incorporated. Within the present investigation, affine and rigid registrations yield comparable values. The restriction to the six parameters of the rigid registration is not a limitation. The differences in size and shape between the tooth and its contra-lateral counterpart generally exhibit only a few percent in the non-abraded volume, validating that the contralateral tooth is a reasonable approximation to quantify, for example, the volume loss as the result of long-term clay pipe smoking. Therefore, this approach allows quantifying the impact of the pipe abrasion on the internal tooth morphology including root canal, dentin, and enamel volumes.

  6. Mass flow rate measurement in abrasive jets using acoustic emission

    NASA Astrophysics Data System (ADS)

    Ivantsiv, V.; Spelt, J. K.; Papini, M.

    2009-09-01

    The repeatability of abrasive jet machining operations is presently limited by fluctuations in the mass flow rate due to powder compaction, stratification and humidity effects. It was found that the abrasive mass flow rate for a typical abrasive jet micromachining setup could be determined by using data from the acoustic emission of the abrasive jet impacting a flat plate. Two methods for extracting the mass flow rate from the acoustic emission were developed and compared. In the first method, the number of particle impacts per unit time was determined by a direct count of peaks in the acoustic emission signal. The second method utilizes the power spectrum density of the acoustic emission in a specific frequency range. Both measures were found to correlate strongly with the mass flow rate measured by weighing samples of blasted powder for controlled time periods. It was found that the peak count method permits measurement of the average frequency of the impacts and the mass flow rate, but can only be applied to flow rates in which the impact frequency is approximately one order of magnitude less than the frequency of the target plate ringing. The power spectrum density method of signal processing is applicable to relatively fine powders and to flow rates at which the average impact frequency is of the same order of magnitude as that of the ringing due to the impact. The acoustic emission technique can be used to monitor particle flow variations over a wide range of time periods and provides a straightforward and accurate means of process control.

  7. Abrasive wear of advanced structural materials

    NASA Astrophysics Data System (ADS)

    Lee, Gun-Young

    Wear of advanced structural materials, namely composites and ceramics, in abrasion has been examined in the present study. A simple physically-based model for the abrasive wear of composite materials is presented based on the mechanics and mechanisms associated with sliding wear in soft (ductile) matrix composites containing hard (brittle) reinforcement particles. The model is based on the assumption that any portion of the reinforcement that is removed as wear debris cannot contribute to the wear resistance of the matrix material. The size of this non-contributing portion of reinforcement is estimated by modeling three primary wear mechanisms, specifically plowing, cracking at the matrix/reinforcement interface or in the reinforcement, and particle removal. Critical variables describing the role of the reinforcement, such as the relative size, fracture toughness, and the nature of the matrix/reinforcement interface, are characterized by a single contribution coefficient, C. Predictions are compared with the results of experimental two-body (pin-on-drum) abrasive wear tests performed on a model aluminum particulate-reinforced epoxy-matrix composite material. In addition, the effects of post heat-treatment on the wear behavior of toughened silicon carbide (ABC-SiC) are investigated by characterizing the role of the microstructures introduced during the post annealing processes. When the annealing temperature is above 1300°C, an aluminum rich secondary phase (nano-precipitate) forms and grows inside the SiC grains. This toughened silicon carbide (ABC-SiC), annealed at temperatures ranging from 0 to 1600°C, is subjected to two- and three-body abrasions with different sizes of abrasives (3˜70 mum). The test results exhibit that the effect of nano-precipitates on wear resistance of post-annealed ABC-SiC is restricted to the abrasion with fine abrasives (3 mum), since nano-precipitates, in the range from 4 nm at 1300°C to 25 nm at 1600°C, are comparable in dimension

  8. The theory of interface slicing

    NASA Technical Reports Server (NTRS)

    Beck, Jon

    1993-01-01

    Interface slicing is a new tool which was developed to facilitate reuse-based software engineering, by addressing the following problems, needs, and issues: (1) size of systems incorporating reused modules; (2) knowledge requirements for program modification; (3) program understanding for reverse engineering; (4) module granularity and domain management; and (5) time and space complexity of conventional slicing. The definition of a form of static program analysis called interface slicing is addressed.

  9. Electrohydrodynamic drying of carrot slices.

    PubMed

    Ding, Changjiang; Lu, Jun; Song, Zhiqing

    2015-01-01

    Carrots have one of the highest levels of carotene, and they are rich in vitamins, fiber and minerals. However, since fresh carrots wilt rapidly after harvest under inappropriate storage conditions, drying has been used to improve their shelf life and retain nutritional quality. Therefore, to further investigate the potential of this method, carrot slices were dried in an EHD system in order to study the effect of different voltages on drying rate. As measures of quality, carotene content and rehydration ratio were, respectively, compared against the conventional oven drying regime. Carotene, the main component of the dried carrot, and rehydration characteristics of the dried product can both indicate quality by physical and chemical changes during the drying process. Mathematical modeling and simulation of drying curves were also performed, using root mean square error, reduced mean square of the deviation and modeling efficiency as the primary criteria to select the equation that best accounts for the variation in the drying curves of the dried samples. Theoretically, the Page model was best suited for describing the drying rate curve of carrot slices at 10kV to 30kV. Experimentally, the drying rate of carrots was notably greater in the EHD system when compared to control, and quality, as determined by carotene content and rehydration ratio, was also improved when compared to oven drying. Therefore, this work presents a facile and effective strategy for experimentally and theoretically determining the drying properties of carrots, and, as a result, it provides deeper insight into the industrial potential of the EHD drying technique. PMID:25874695

  10. Electrohydrodynamic Drying of Carrot Slices

    PubMed Central

    Ding, Changjiang; Lu, Jun; Song, Zhiqing

    2015-01-01

    Carrots have one of the highest levels of carotene, and they are rich in vitamins, fiber and minerals. However, since fresh carrots wilt rapidly after harvest under inappropriate storage conditions, drying has been used to improve their shelf life and retain nutritional quality. Therefore, to further investigate the potential of this method, carrot slices were dried in an EHD system in order to study the effect of different voltages on drying rate. As measures of quality, carotene content and rehydration ratio were, respectively, compared against the conventional oven drying regime. Carotene, the main component of the dried carrot, and rehydration characteristics of the dried product can both indicate quality by physical and chemical changes during the drying process. Mathematical modeling and simulation of drying curves were also performed, using root mean square error, reduced mean square of the deviation and modeling efficiency as the primary criteria to select the equation that best accounts for the variation in the drying curves of the dried samples. Theoretically, the Page model was best suited for describing the drying rate curve of carrot slices at 10kV to 30kV. Experimentally, the drying rate of carrots was notably greater in the EHD system when compared to control, and quality, as determined by carotene content and rehydration ratio, was also improved when compared to oven drying. Therefore, this work presents a facile and effective strategy for experimentally and theoretically determining the drying properties of carrots, and, as a result, it provides deeper insight into the industrial potential of the EHD drying technique. PMID:25874695

  11. Abrasion resistance of medical glove materials.

    PubMed

    Walsh, Donna L; Schwerin, Matthew R; Kisielewski, Richard W; Kotz, Richard M; Chaput, Maria P; Varney, George W; To, Theresa M

    2004-01-15

    Due to the increasing demand for nonlatex medical gloves in the health-care community, there is a need to assess the durability of alternative glove materials. This study examines durability characteristics of various glove materials by abrasion resistance testing. Natural rubber latex (latex), polyvinyl chloride (vinyl), acrylonitrile butadiene (nitrile), polychloroprene (neoprene), and a styrene-ethylene/butylene-styrene block copolymer (SEBS) were tested. All test specimens, with the exception of the vinyl, were obtained from surgical gloves. Unaged out-of-the-box specimens as well as those subjected to various degrees of artificial aging were included in the study. After the abrasion sequence, the barrier integrity of the material was assessed through the use of a static leak test. Other traditional tests performed on these materials were viral penetration to validate the abrasion data and tear testing for comparative purposes. The results indicate that specific glove-material performance is dependent upon the particular test under consideration. Most notably, abrasion, even in controlled nonsevere conditions, may compromise to varying degrees the barrier integrity of latex, vinyl, SEBS, nitrile, and neoprene glove materials. However, as evidenced by the results of testing three brands of neoprene gloves, the abrasion resistance of any one glove material may be significantly affected by variations in production processes. PMID:14689500

  12. An investigation into magnetic electrolytic abrasive turning

    NASA Astrophysics Data System (ADS)

    Mahdy, M. A. M.; Ismaeial, A. L.; Aly, F. F.

    2013-07-01

    The magnetic electrolytic abrasive turning (MEAT) process as a non-traditional machining is used to obtain surface finishing like mirror. MEAT provides one of the best alternatives for producing complex shapes with good finish in advanced materials used in aircraft and aerospace industries. The improvement of machining accuracy of MEAT continues to be a major challenge for modern industry. MEAT is a hybrid machining which combines two or more processes to remove material. The present research focuses on the development of precision electrochemical turning (ECT) under the effects of magnetic field and abrasives. The effect of magnetic flux density, electrochemical conditions and abrasive parameters on finishing efficiency and surface roughness are investigated. An empirical relationship is deduced.

  13. Early abrasion of outer silicone insulation after intracardiac lead friction in a patient with cardiac device-related infective endocarditis.

    PubMed

    Ząbek, Andrej; Małecka, Barbara; Kołodzińska, Agnieszka; Maziarz, Andrej; Lelakowski, Jacek; Kutarski, Andrej

    2012-06-01

    We present a case of a 76-year-old woman on a permanent pacing device, with early abrasion of silicone endocardial lead insulations complicated by lead-dependent infective endocarditis 13 months after placement of an implantable pulse generator. The leads were removed using transvenous technique with direct traction, and with no additional tools. In the previous report, a set of additional tools was used, and therefore intraoperative endocardial lead abrasions or mechanical damage of leads could have not been excluded. The present case undoubtedly proves that the friction of leads against each other may result in abrasions of insulation of the intracardiac section of the lead. PMID:21070260

  14. Corneal Abrasions and Corneal Foreign Bodies.

    PubMed

    Ahmed, Faheem; House, Robert James; Feldman, Brad Hal

    2015-09-01

    Corneal abrasions and corneal foreign bodies are frequently encountered ophthalmological injuries that are commonly diagnosed and managed by primary care physicians. The clinical course of a corneal epithelial defect can range from a relatively benign self-healing abrasion to a potentially sight-threatening complication such as a corneal ulcer, recurrent erosion, or traumatic iritis. A detailed clinical history regarding risk factors and exposure, along with a thorough slit lamp examination with fluorescein dye are essential for proper diagnosis and treatment, as well as to rule out penetrating globe injuries. Referral to an ophthalmologist is recommended in difficult cases or if other injuries are suspected. PMID:26319343

  15. Friction and abrasion of elastomeric materials

    NASA Technical Reports Server (NTRS)

    Gent, A. N.

    1975-01-01

    An abrasion apparatus is described. Experimental measurements are reported for four representative elastomeric materials, including a typical high-quality tire tread material and a possible replacement material for aircraft tire treads based on transpolypentenamer (TPPR). Measurements are carried out at different levels of frictional work input, corresponding to different severities of wear, and at both ambient temperature and at 100 C. Results indicate the marked superiority in abrasion resistance of the material based on TPPR, especially at 100 C, in comparison with the other materials examined.

  16. Universal scaling relations for pebble abrasion

    NASA Astrophysics Data System (ADS)

    Litwin, K. L.; Jerolmack, D. J.

    2012-12-01

    The process of abrasion of gravel in bed load transport results from particle-to-particle collisions, where the energy involved is sufficient to cause chipping and spallation but not fragmentation of parent grains. The removed rock material is not infinitesimal; daughter products as large as coarse sand can be produced. Although previous work has shown that lithology, grain shape, and energy of collision are contributing factors that control abrasion rates of river-bed material, little is known regarding the relationship between these factors and diminution rates. Here we explicitly isolate and investigate how these three factors influence rates of abrasion and the size distribution of daughter products, with laboratory experiments. The apparatus is a double pendulum (Newton's cradle) that produces well-controlled binary collisions. A high-speed camera precisely measures collision energy, while mass of parent rocks. and the size and shape distributions of daughter products, are measured periodically. We examined abrasion of initially square-cut 'rocks' as they underwent successive collisions in the binary collision apparatus. We have examined mass loss rate for varied lithologies, and observe a similar power-law relationship between impact energy and mass abraded. When normalized by sensible material properties, mass loss curves for all materials collapse onto a single curve, suggesting that the underlying mechanics of abrasion for different materials are the same. The relationship does not display the linear trend expected from pure energetics, and we suggest that this is a shape effect as protruding - and hence easily eroded - corners are worn away. Analysis of daughter-product particle size distributions for different lithology fragments - including natural rocks and also bricks - show the same functional form. Surprisingly, it is the power-law relation expected for brittle materials undergoing fragmentation. This suggests that brittle fracture theory also

  17. Recent progress of abrasion-resistant materials: learning from nature.

    PubMed

    Meng, Jingxin; Zhang, Pengchao; Wang, Shutao

    2016-01-21

    Abrasion-resistant materials have attracted great attention for their broad applications in industry, biomedicine and military. However, the development of abrasion-resistant materials that have with unique features such as being lightweight and flexible remains a great challenge in order to satisfy unmet demands. The outstanding performance of natural abrasion-resistant materials motivates the development of new bio-inspired abrasion-resistant materials. This review summarizes the recent progress in the investigation of natural abrasion-resistant materials to explore their general design principles (i.e., the correlation between chemical components and structural features). Following natural design principles, several artificial abrasion-resistant materials have shown unique abrasion-resistant properties. The potential challenges in the future and possible solutions for designing bio-inspired abrasion-resistant materials are also briefly discussed. PMID:26335377

  18. Tryptophan availability modulates serotonin release from rat hypothalamic slices

    NASA Technical Reports Server (NTRS)

    Schaechter, Judith D.; Wurtman, Richard J.

    1989-01-01

    The relationship between the tryptophan availability and serononin release from rat hypothalamus was investigated using a new in vitro technique for estimating rates at which endogenous serotonin is released spontaneously or upon electrical depolarization from hypothalamic slices superfused with a solution containing various amounts of tryptophan. It was found that the spontaneous, as well as electrically induced, release of serotonin from the brain slices exhibited a dose-dependent relationship with the tryptophan concentration of the superfusion medium.

  19. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... exceeded. (j) All employees using abrasive wheels shall be protected by eye protection equipment in accordance with the requirements of subpart I of this part except when adequate eye protection is afforded by eye shields which are permanently attached to the bench or floor stand....

  20. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  1. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  2. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  3. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  4. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... spindle speed under all conditions of normal grinding. The rated maximum speed of the wheel shall not be...) Floor stand and bench mounted abrasive wheels used for external grinding shall be provided with safety guards (protection hoods). The maximum angular exposure of the grinding wheel periphery and sides...

  5. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... spindle speed under all conditions of normal grinding. The rated maximum speed of the wheel shall not be...) Floor stand and bench mounted abrasive wheels used for external grinding shall be provided with safety guards (protection hoods). The maximum angular exposure of the grinding wheel periphery and sides...

  6. Evaluation and Treatment of Perioperative Corneal Abrasions

    PubMed Central

    Segal, Kira L.; Fleischut, Peter M.; Kim, Charles; Levine, Ben; Faggiani, Susan L.; Banerjee, Samprit; Gadalla, Farida; Lelli, Gary J.

    2014-01-01

    Purpose. To evaluate perioperative risk factors for corneal abrasion (CA) and to determine current care for perioperative CA in a tertiary care setting. Methods. Hospital-based, cross-sectional study. In Operating Room and Post-Anesthesia Care Units patients, a comparison of cases and controls was evaluated to elucidate risk factors, time to treatment, and most common treatments prescribed for corneal abrasions. Results. 86 cases of corneal abrasion and 89 controls were identified from the 78,542 surgical procedures performed over 2 years. Statistically significant risk factors were age (P = 0.0037), general anesthesia (P < 0.001), greater average estimated blood loss (P < 0.001), eyes taped during surgery (P < 0.001), prone position (P < 0.001), trendelenburg position (P < 0.001), and supplemental oxygen en route to and in the Post-Anesthesia Care Units (P < 0.001). Average time to complaint was 129 minutes. 94% of cases had an inpatient ophthalmology consult, with an average time to consult of 164 minutes. The most common treatment was artificial tears alone (40%), followed by combination treatment of antibiotic ointment and artificial tears (35.3%). Conclusions. Trendelenburg positioning is a novel risk factor for CA. Diagnosis and treatment of perioperative corneal abrasions by an ophthalmologist typically require three hours in the tertiary care setting. PMID:24672709

  7. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  8. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Abrasive wheels. 1915.134 Section 1915.134 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Tools and Related...

  9. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Abrasive wheels. 1915.134 Section 1915.134 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Tools and Related...

  10. Dust transport and abrasion assessment within simulated standing vegetation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop residues are useful in protecting the top soil from depletion and abrasion due to wind erosion. A wind tunnel study was done to measure sand transport and abrasion energies within the simulated artificial standing vegetation. Wind profiles, relative abrasion energies and rates of sand dischar...

  11. Relationship between abrasive wear and microstructure of composite resins.

    PubMed

    Draughn, R A; Harrison, A

    1978-08-01

    The in vitro abrasion resistance of seven commercial composite resin restorative materials has been measured. Analysis of the composite microstructures shows that abrasion rates are dependent upon the size, hardness, and volume fraction of particles in the material. The most abrasion-resistant composites contain a high volume fraction of large, hard particles. PMID:278840

  12. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  13. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  14. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  15. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  16. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  17. Effect of ceramic coating by aerosol deposition on abrasion resistance of a resin composite material.

    PubMed

    Taira, Yohsuke; Hatono, Hironori; Mizukane, Masahiro; Tokita, Masahiro; Atsuta, Mitsuru

    2006-12-01

    Aerosol deposition (AD coating) is a novel technique to coat solid substances with a ceramic film. The purpose of the present study was to investigate the effect of AD coating on abrasion resistance of a resin composite material. A 5-microm-thick aluminum oxide layer was created on the polymerized resin composite. The specimen was cyclically abraded using a toothbrush abrasion simulator for 100,000 cycles. Abraded surface was then measured with a profilometer to determine the average roughness (Ra) and maximum roughness (Rmax). It was found that abrasion cycling increased the Ra value of the No-AD-coating group, but decreased the Ra and Rmax values of the AD coating group. Moreover, the AD coating group showed significantly smaller Ra and Rmax values after 100,000 abrasion cycles as compared to the No-coating control group. Microscopic observation supported these findings. In conclusion, the resistance of the resin composite against toothbrush abrasion was improved by AD coating. PMID:17338303

  18. Subsurface mechanical damage during bound abrasive grinding of fused silica glass

    NASA Astrophysics Data System (ADS)

    Blaineau, P.; André, D.; Laheurte, R.; Darnis, P.; Darbois, N.; Cahuc, O.; Neauport, J.

    2015-10-01

    The subsurface damage (SSD) introduced during bound abrasive grinding of fused silica glass was measured using a wet etch technique. Various process parameters and grinding configurations were studied. The relation between the SSD depth, the process parameters and forces applied by the grinding wheel on the sample was investigated and compared to a simulation using a discrete element method to model the grinding interface. The results reveal a relation between the SSD depth and the grinding forces normalized by the abrasive concentration. Regarding the creation of the SSD, numerical simulations indicate that only a small fraction of the largest particles in the diamond wheel are responsible for the depth of the damaged layer.

  19. Influence of alumina and titanium dioxide coatings on abrasive wear resistance of AISI 1045 steel

    NASA Astrophysics Data System (ADS)

    Santos, A.; Remolina, A.; Marulanda, J.

    2016-02-01

    This project aims to compare the behaviour of an AISI 1045 steel's abrasive wear resistance when is covered with aluminium oxide (Al2O3) or Titanium dioxide (TiO2), of nanometric size, using the technique of thermal hot spray, which allows to directly project the suspension particles on the used substrate. The tests are performed based on the ASTM G65-04 standard (Standard Test Method for Measuring Abrasion Using the Dry Sand/Rubber Apparatus). The results show that the amount of, lost material increases linearly with the travelled distance; also determined that the thermal treatment of hardening-tempering and the alumina and titanium dioxide coatings decrease in average a 12.9, 39.6 and 29.3% respectively the volume of released material during abrasive wear test.

  20. Air-propelled abrasive grit for postemergence in-row weed control in field corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic growers need additional tools for weed control. A new technique involving abrasive grit propelled by compressed air was tested in field plots. Grit derived from corn cobs was directed at seedlings of summer annual weeds growing at the bases of corn plants when the corn was at differing early...

  1. Adiabatic slice-selective excitation for surface coils.

    PubMed

    Shen, J; Rothman, D L

    1997-01-01

    A novel RF pulse designed to perform a diabatic slice-selective excitation for surface coils (ASSESS) is proposed in which Bzero gradient is modulated in concert with RF frequency modulation. Within the selected slice, the principles of BIR4 pulses are employed to obtain well-defined, pure-phase and self-refocused spin rotation of arbitrary flip angles despite the presence of high B1 inhomogeneity produced by surface coils. Outside the slice, advantage is taken of the B1 field to dephase equilibrium magnetization to achieve slice selection or outer-volume suppression. This scheme should be useful for many localization techniques. Quaternion analysis of the overall propagator of the proposed pulse and numerical simulations using Bloch equations are performed. The pulse is tested experimentally on a phantom sample. PMID:9169211

  2. Slicing through Spaghetti Code.

    ERIC Educational Resources Information Center

    Luehrmann, Arthur

    1983-01-01

    Stresses the importance of teaching "structured programming," and gives examples of good and bad programing styles and suggestions for teaching good programing techniques. The language used is BASIC, and numerous examples are provided. (EAO)

  3. Wheel Abrasion Experiment Conducted on Mars

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.

    1998-01-01

    Sojourner rover showing Lewis' wheel abrasion experiment. The Mars Pathfinder spacecraft soft-landed on Mars on July 4, 1997. Among the many experiments on its small Sojourner rover are three technology experiments from the NASA Lewis Research Center, including the Wheel Abrasion Experiment (WAE). The WAE was designed, built, delivered, and operated on Mars by a team of engineers and scientists from Lewis' Photovoltaics and Space Environments Branch. This experiment collected data to assess wheel surface wear on the Sojourner. It used a specially designed rover wheel, with thin films (200 to 1000 angstroms) of aluminum, nickel, and platinum deposited on black, anodized aluminum strips attached to the rover's right center wheel. As the wheel spun in the Martian soil, a photovoltaic sensor monitored changes in film reflectivity. These changes indicated abrasion of the metal films by Martian surface material. Rolling wear data were accumulated by the WAE. Also, at frequent intervals, all the rover wheels, except the WAE test wheel, were locked to hold the rover stationary while the test wheel alone was spun and dug into the Martian regolith. These tests created wear conditions more severe than simple rolling. The WAE will contribute substantially to our knowledge of Martian surface characteristics. Marked abrasion would indicate a surface composed of hard, possibly sharply edged grains, whereas lack of abrasion would suggest a somewhat softer surface. WAE results will be correlated with ground simulations to determine which terrestrial materials behave most like those on Mars. This knowledge will enable a deeper understanding of erosion processes on Mars and the role they play in Martian surface evolution. Preliminary results show that electrostatic charging of the rover wheels sometimes caused dust to accumulate on the WAE wheel, making interpretation of the reflectance data problematic. If electrostatic charging is the mechanism for dust attraction, this indicates

  4. Abrasion resistance of linings in filament wound composite pipe

    SciTech Connect

    Hall, S.C.

    1999-07-01

    Fiberglass filament wound composite pipe has numerous industrial applications including transportation of petroleum and natural gas. Its corrosion resistance is well known but it can be susceptible to abrasion and erosion when it is used to transport slurries or dry gas containing sand particles. However, composite pipe can be manufactured integrally with abrasion resistant linings which protect the pipe from abrasion and erosion and increase its life. Laboratory investigations were performed to determine the effect of abrasive flows through polyurea-lined and unlined glass-reinforced epoxy (GRE) pipe, ultra-high molecular weight (UHMW) polyethylene (PE) pipe, and unlined steel pipe. Results are provided for the abrasion resistance, chemical resistance, adhesion strength, elongation, tensile strength, impact resistance and hardness of selected linings. The abrasion resistance of polyurea-lined composite pipe proved to be almost as resistant to abrasion and erosion as unlined steel pipe without the electrochemical corrosion associated with steel pipe.

  5. Abrasion-Resistant Technology and its Prospect for CFB Boilers

    NASA Astrophysics Data System (ADS)

    Zheng, H.; Li, Y. J.; Wang, L. J.; Liu, S. H.; Dou, Q. R.

    In recent years, CFB boilers (CFBB) have been widely used in the commercial power plants due to its environmental benefits, high combustion efficiency, wide coal flexibility, and some other advantages. At the same time, the abrasion problem, the greatest weakness of this kind of boiler, has been gradually exposed in its application process. The abrasion, particularly on key parts such as the heating surface of water-cooled wall, furnace corners, separator entrance, seriously restricts the long-period operation ability of the CFBB. This article discusses current development status for various abrasion resistant refractory materials used in a CFBB. Some comments are provided for developing new high-performance abrasion resistant refractory materials and rapid-repaired materials according to the abrasion principle and the abrasion on different parts, as well as the economical and environmental requirements for the material. The abrasion solution and operation period of CFBB can be better improved given realization.

  6. Liquid abrasive pressure pot scoping tests report

    SciTech Connect

    Archibald, K.E.

    1996-01-01

    The primary initiatives of the LITCO Decontamination Development group at the Idaho Chemical Process Plant (ICPP) are the development of methods to eliminate the use of sodium bearing decontamination chemicals and minimization of the amount of secondary waste generated during decontamination activities. In July of 1994, a Commerce Business Daily (CBD) announcement was issued by the INEL to determine commercial interest in the development of an in-situ liquid abrasive grit blasting system. As a result of the CBD announcement, Klieber & Schulz issued an Expression of Interest letter which stated they would be interested in testing a prototype Liquid Abrasive Pressure Pot (LAPP). LITCO`s Decontamination group and Kleiber & Schulz entered into a Cooperative Research and Development Agreement (CRADA) in which the Decontamination Development group tested the prototype LAPP in a non-radioactive hot cell mockup. Test results are provided.

  7. Loose abrasive slurries for optical glass lapping

    SciTech Connect

    Neauport, Jerome; Destribats, Julie; Maunier, Cedric; Ambard, Chrystel; Cormont, Philippe; Pintault, B.; Rondeau, Olivier

    2010-10-20

    Loose abrasive lapping is widely used to prepare optical glass before its final polishing. We carried out a comparison of 20 different slurries from four different vendors. Slurry particle sizes and morphologies were measured. Fused silica samples were lapped with these different slurries on a single side polishing machine and characterized in terms of surface roughness and depth of subsurface damage (SSD). Effects of load, rotation speed, and slurry concentration during lapping on roughness, material removal rate, and SSD were investigated.

  8. Abrasive slurry composition for machining boron carbide

    DOEpatents

    Duran, Edward L.

    1985-01-01

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

  9. Abrasive slurry composition for machining boron carbide

    DOEpatents

    Duran, E.L.

    1984-11-29

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

  10. Predicting abrasive wear with coupled Lagrangian methods

    NASA Astrophysics Data System (ADS)

    Beck, Florian; Eberhard, Peter

    2015-05-01

    In this paper, a mesh-less approach for the simulation of a fluid with particle loading and the prediction of abrasive wear is presented. We are using the smoothed particle hydrodynamics (SPH) method for modeling the fluid and the discrete element method (DEM) for the solid particles, which represent the loading of the fluid. These Lagrangian methods are used to describe heavily sloshing fluids with their free surfaces as well as the interface between the fluid and the solid particles accurately. A Reynolds-averaged Navier-Stokes equations model is applied for handling turbulences. We are predicting abrasive wear on the boundary geometry with two different wear models taking cutting and deformation mechanisms into account. The boundary geometry is discretized with special DEM particles. In doing so, it is possible to use the same particle type for both the calculation of the boundary conditions for the SPH method as well as the DEM and for predicting the abrasive wear. After a brief introduction to the SPH method and the DEM, the handling of the boundary and the coupling of the fluid and the solid particles are discussed. Then, the applied wear models are presented and the simulation scenarios are described. The first numerical experiment is the simulation of a fluid with loading which is sloshing inside a tank. The second numerical experiment is the simulation of the impact of a free jet with loading to a simplified pelton bucket. We are especially investigating the wear patterns inside the tank and the bucket.

  11. Circular Signs of the Rock Abrasion Tool

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image was taken by Mars Exploration Rover Opportunity's front hazard-avoidance camera, providing a circular sign of the success of the rover's first grinding of a rock. The round, shallow hole seen in this image is on a rock dubbed 'McKittrick,' located in the 'El Capitan' area of the larger outcrop near Opportunity's landing site.

    Opportunity used its rock abrasion tool to grind off a patch of rock 45.5 millimeters (1.8 inches) in diameter during the 30th martian day, or sol, of its mission (Feb. 23, 2004). The grinding exposed fresh rock for close inspection by the rover's microscopic imager and two spectrometers located on its robotic arm. The Honeybee Robotics team, which designed and operates the rock abrasion tool, determined the depth of the cut at 'McKittrick' to be 4.4 millimeters (0.17 inches) deep.

    On sol 34 (Feb. 27, 2004), the rover is scheduled to grind into its second target on the 'El Capitan' area, a rock dubbed 'Guadalupe' in the upper middle part of this image. The rock abrasion tools on both Mars Exploration Rovers were supplied by Honeybee Robotics, New York, N.Y.

  12. Rapid ultrathin slice plastination of embalmed specimens with minimal tissue loss.

    PubMed

    Soal, S; Pollard, M; Burland, G; Lissaman, R; Wafer, M; Stringer, M D

    2010-07-01

    A modified technique of producing 1 mm (ultrathin) E12 plastinated slices of tissue specimens from embalmed cadavers for anatomical teaching and research is described. Specimens up to 150 mm in length and width were embedded in polyurethane foam and serially sectioned using an OMAS C300 food slicer. Individual slices were then processed by cold dehydration, degreasing, resin impregnation, mounting and curing. Bone-containing specimens were first decalcified. Tissue slices could be cut with remarkable accuracy (0.98 +/- 0.01 mm per slice) and minimal tissue loss (less than 2% per slice). The entire production process could be achieved in 25 days and was associated with tissue volume shrinkage of no more than 6%. These results demonstrate a relatively rapid method of producing ultrathin E12 slices with minimal tissue loss. The technique may be particularly applicable to submacroscopic morphologic studies and three-dimensional reconstruction in clinical anatomy. PMID:20235170

  13. Trumpet slices in Kerr spacetimes.

    PubMed

    Dennison, Kenneth A; Baumgarte, Thomas W; Montero, Pedro J

    2014-12-31

    We introduce a new time-independent family of analytical coordinate systems for the Kerr spacetime representing rotating black holes. We also propose a (2+1)+1 formalism for the characterization of trumpet geometries. Applying this formalism to our new family of coordinate systems we identify, for the first time, analytical and stationary trumpet slices for general rotating black holes, even for charged black holes in the presence of a cosmological constant. We present results for metric functions in this slicing and analyze the geometry of the rotating trumpet surface. PMID:25615297

  14. A new dimension to conservative dentistry: Air abrasion

    PubMed Central

    Hegde, Vivek S; Khatavkar, Roheet A

    2010-01-01

    Air abrasion dentistry has evolved over a period of time from a new concept of an alternative means of cavity preparation to an essential means of providing a truly conservative preparation for preservation of a maximal sound tooth structure. The development of bonded restorations in combination with air abrasion dentistry provides a truly minimal intervention dentistry. This article reviews the development of air abrasion, its clinical uses, and the essential accessories required for its use. PMID:20582212

  15. Pebble Jammed in Rock Abrasion Tool

    NASA Technical Reports Server (NTRS)

    2004-01-01

    After the rock abrasion tool on NASA's Mars Exploration Rover Opportunity stopped working on sol 199 (Aug. 15, 2004), rover operators used the panoramic camera to take this image the next day for help in diagnosing the problem. The tool was closer than the camera could focus on sharply, but the image does show a dark spot just left of center, which engineers have determined is likely to be a pebble jammed between the cutting-blade rotor and the wire-brush rotor. If that diagnosis is confirmed by further analysis, the tool will likely be commanded to turn the rotors in reverse to release the pebble.

  16. Mars Pathfinder Wheel Abrasion Experiment Ground Test

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Siebert, Mark W.

    1998-01-01

    The National Aeronautics and Space Administration (NASA) sent a mission to the martian surface, called Mars Pathfinder. The mission payload consisted of a lander and a rover. The primary purpose of the mission was demonstrating a novel entry, descent, and landing method that included a heat shield, a parachute, rockets, and a cocoon of giant air bags. Once on the surface, the spacecraft returned temperature measurements near the Martian surface, atmosphere pressure, wind speed measurements, and images from the lander and rover. The rover obtained 16 elemental measurements of rocks and soils, performed soil-mechanics, atmospheric sedimentation measurements, and soil abrasiveness measurements.

  17. Abrasive Wear Behaviour of COPPER-SiC and COPPER-SiO2 Composites

    NASA Astrophysics Data System (ADS)

    Umale, Tejas; Singh, Amarjit; Reddy, Y.; Khatitrkar, R. K.; Sapate, S. G.

    The present paper reports abrasive wear behaviour of copper matrix composites reinforced with silicon carbide and silica particles. Copper - SiC (12%) and Copper-SiO2 (9%) composites were prepared by powder metallurgical technique. Metallography, image analysis and hardness studies were carried out on copper composites. The abrasive wear experiments were carried out using pin on disc apparatus. The effect of sliding distance and load was studied on Copper - SiC (12%) and Copper-SiO2 (9%) composites. The abrasive wear volume loss increased with sliding distance in both the composites although the magnitude of increase was different in each case. Copper - SiC (12%) composites exhibited relatively better abrasion resistance as compared to and Copper-SiO2 (9%) composites. The abraded surfaces were observed under scanning electron microscope to study the morphology of abraded surfaces and operating wear mechanism. The analysis of wear debris particles was also carried out to substantiate the findings of the investigation.

  18. Effect of Bioactive Glass air Abrasion on Shear Bond Strength of Two Adhesive Resins to Decalcified Enamel

    PubMed Central

    Eshghi, Alireza; Khoroushi, Maryam; Rezvani, Alireza

    2014-01-01

    Objective: Bioactive glass air abrasion is a conservative technique to remove initial decalcified tissue and caries. This study examined the shear bond strength of composite resin to sound and decalcified enamel air-abraded by bioactive glass (BAG) or alumina using etch-and-rinse and self-etch adhesives. Materials and Methods: Forty-eight permanent molars were root-amputated and sectioned mesiodistally. The obtained 96 specimens were mounted in acrylic resin; the buccal and lingual surfaces remained exposed. A demineralizing solution was used to decalcify half the specimens. Both sound and decalcified specimens were divided into two groups of alumina and bioactive glass air abrasion. In each group, the specimens were subdivided into two subgroups of Clearfil SE Bond or OptiBond FL adhesives (n=12). Composite resin cylinders were bonded on enamel surfaces cured and underwent thermocycling. The specimens were tested for shear bond strength. Data were analyzed using SPSS 16.0 and three-way ANOVA (α=0.05). Similar to the experimental groups, the enamel surface of one specimen underwent SEM evaluation. Results: No significant differences were observed in composite resin bond strength subsequent to alumina or bioactive glass air abrasion preparation techniques (P=0.987). There were no statistically significant differences between the bond strength of etch-and-rinse and self-etch adhesive groups (P=1). Also, decalcified or intact enamel groups had no significant difference (P=0.918). However, SEM analysis showed much less enamel irregularities with BAG air abrasion compared to alumina air abrasion. Conclusion: Under the limitations of this study, preparation of both intact and decalcified enamel surfaces with bioactive glass air abrasion results in similar bond strength of composite resin in comparison with alumina air abrasion using etch-&-rinse or self-etch adhesives. PMID:25628694

  19. Preparation and Applications of Organotypic Thymic Slice Cultures.

    PubMed

    Sood, Aditi; Dong, Mengqi; Melichar, Heather J

    2016-01-01

    Thymic selection proceeds in a unique and highly organized thymic microenvironment resulting in the generation of a functional, self-tolerant T cell repertoire. In vitro models to study T lineage commitment and development have provided valuable insights into this process. However, these systems lack the complete three-dimensional thymic milieu necessary for T cell development and, therefore, are incomplete approximations of in vivo thymic selection. Some of the challenges related to modeling T cell development can be overcome by using in situ models that provide an intact thymic microenvironment that fully supports thymic selection of developing T cells. Thymic slice organotypic cultures complement existing in situ techniques. Thymic slices preserve the integrity of the thymic cortical and medullary regions and provide a platform to study development of overlaid thymocytes of a defined developmental stage or of endogenous T cells within a mature thymic microenvironment. Given the ability to generate ~20 slices per mouse, thymic slices present a unique advantage in terms of scalability for high throughput experiments. Further, the relative ease in generating thymic slices and potential to overlay different thymic subsets or other cell populations from diverse genetic backgrounds enhances the versatility of this method. Here we describe a protocol for the preparation of thymic slices, isolation and overlay of thymocytes, and dissociation of thymic slices for flow cytometric analysis. This system can also be adapted to study non-conventional T cell development as well as visualize thymocyte migration, thymocyte-stromal cell interactions, and TCR signals associated with thymic selection by two-photon microscopy. PMID:27585240

  20. Mars Exploration Rovers' Rock Abrasion Tool

    NASA Astrophysics Data System (ADS)

    Gorevan, S.; Myrick, T.; Davis, K.; Ji, J.; Bartlett, P.; Mukherjee, S.; Arafat, T.

    2003-04-01

    Each of the twin 2003 Mars Exploration Rovers will be equipped with a Rock Abrasion Tool (RAT) designed and tested by Honeybee Robotics. The RAT is a robotic grinding tool and science instrument about the size of a soda can and weighing less than 690 grams that is carried by the robotic arm or Instrument Deployment Device (IDD) of the rover. The primary purpose of the RAT is to remove the dust and surface rind from Mars rock targets to reveal the underlying petrographic features. After the RAT is placed and preloaded against the target rock by the IDD, all operations of the RAT are performed autonomously. Using three small motors to drive the rotation, revolve and z-axis subassemblies the RAT removes a 45 mm diameter, 5 mm deep patch of rock. The RAT has a resin-bonded diamond abrasion wheel and two brushes to provide a clean observation surface for the three surface instruments - APXS, Microscopic Imager and Moessbauer Spectrometer. Detailed design and operation descriptions, as well as recent qualification and operational testing results will be presented.

  1. Ingot slicing machine and method

    NASA Technical Reports Server (NTRS)

    Kuo, Y. S. (Inventor)

    1984-01-01

    An improved method for simultaneously slicing one or a multiplicity of boules of silicon into silicon wafers is described. A plurality of vertical stacks of horizontal saw blades of circular configuration are arranged in juxtaposed coaxial alignment. Each blade is characterized by having a cutting diameter slightly greater than the cutting diameter of the blade arranged immediately above, imparting a simultaneous rotation to the blades.

  2. AMBER: a PIC slice code for DARHT

    NASA Astrophysics Data System (ADS)

    Vay, Jean-Luc; Fawley, William

    1999-11-01

    The accelerator for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility will produce a 4-kA, 20-MeV, 2-μ s output electron beam with a design goal of less than 1000 π mm-mrad normalized transverse emittance and less than 0.5-mm beam centroid motion. In order to study the beam dynamics throughout the accelerator, we have developed a slice Particle-In-Cell code named AMBER, in which the beam is modeled as a time-steady flow, subject to self, as well as external, electrostatic and magnetostatic fields. The code follows the evolution of a slice of the beam as it propagates through the DARHT accelerator lattice, modeled as an assembly of pipes, solenoids and gaps. In particular, we have paid careful attention to non-paraxial phenomena that can contribute to nonlinear forces and possible emittance growth. We will present the model and the numerical techniques implemented, as well as some test cases and some preliminary results obtained when studying emittance growth during the beam propagation.

  3. Organotypic slice cultures of human gastric and esophagogastric junction cancer.

    PubMed

    Koerfer, Justus; Kallendrusch, Sonja; Merz, Felicitas; Wittekind, Christian; Kubick, Christoph; Kassahun, Woubet T; Schumacher, Guido; Moebius, Christian; Gaßler, Nikolaus; Schopow, Nikolas; Geister, Daniela; Wiechmann, Volker; Weimann, Arved; Eckmann, Christian; Aigner, Achim; Bechmann, Ingo; Lordick, Florian

    2016-07-01

    Gastric and esophagogastric junction cancers are heterogeneous and aggressive tumors with an unpredictable response to cytotoxic treatment. New methods allowing for the analysis of drug resistance are needed. Here, we describe a novel technique by which human tumor specimens can be cultured ex vivo, preserving parts of the natural cancer microenvironment. Using a tissue chopper, fresh surgical tissue samples were cut in 400 μm slices and cultivated in 6-well plates for up to 6 days. The slices were processed for routine histopathology and immunohistochemistry. Cytokeratin stains (CK8, AE1/3) were applied for determining tumor cellularity, Ki-67 for proliferation, and cleaved caspase-3 staining for apoptosis. The slices were analyzed under naive conditions and following 2-4 days in vitro exposure to 5-FU and cisplatin. The slice culture technology allowed for a good preservation of tissue morphology and tumor cell integrity during the culture period. After chemotherapy exposure, a loss of tumor cellularity and an increase in apoptosis were observed. Drug sensitivity of the tumors could be assessed. Organotypic slice cultures of gastric and esophagogastric junction cancers were successfully established. Cytotoxic drug effects could be monitored. They may be used to examine mechanisms of drug resistance in human tissue and may provide a unique and powerful ex vivo platform for the prediction of treatment response. PMID:27073068

  4. Microwave sintering of sol-gel derived abrasive grain

    DOEpatents

    Plovnick, Ross; Celikkaya, Ahmet; Blake, Rodger D.

    1997-01-01

    A method is provided for making microwave-sintered, free flowing alpha alumina-based ceramic abrasive grain, under conditions effective to couple microwaves with calcined alpha alumina-based abrasive gain precursor and sinter it at a temperature of at least about 1150.degree. C.

  5. Soybean seedlings tolerate abrasion from air-propelled grit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New tools for controlling weeds would be useful for soybean production in organic systems. Air-propelled abrasive grit is one such tool that performs well for in-row weed control in corn, but crop safety in soybean is unknown. We examined responses to abrasion by corn-cob grit of soybean seedlings a...

  6. Sand abrasion injury and biomass partitiioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind blown soil particle abrasion negatively impacts millions of hectares of crops annually. The goal of this study was to examine the effects of wind and wind blown sand abrasion damage on cotton (Gossypium hirsutum L.) seedling biomass partitioning to leaves, stems, and roots. Seedlings of three ...

  7. 29 CFR 1926.303 - Abrasive wheels and tools.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 8 2014-07-01 2014-07-01 false Abrasive wheels and tools. 1926.303 Section 1926.303 Labor... (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Tools-Hand and Power § 1926.303 Abrasive wheels and tools. (a) Power. All grinding machines shall be supplied with sufficient power to maintain...

  8. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Abrasive device and accessories. 872.6010 Section 872.6010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and...

  9. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Abrasive device and accessories. 872.6010 Section 872.6010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and...

  10. Abrasion of 6 dentifrices measured by vertical scanning interference microscopy

    PubMed Central

    PASCARETTI-GRIZON, Florence; MABILLEAU, Guillaume; CHAPPARD, Daniel

    2013-01-01

    Objectives The abrasion of dentifrices is well recognized to eliminate the dental plaque. The aims of this study were to characterize the abrasive powders of 6 dentifrices (3 toothpastes and 3 toothpowders) and to measure the abrasion on a test surface by Vertical Scanning Interference microscopy (VSI). Material and Methods Bright field and polarization microscopy were used to identify the abrasive particles on the crude dentifrices and after prolonged washes. Scanning electron microscopy and microanalysis characterized the shape and nature of the particles. Standardized and polished blocks of poly(methylmethacrylate) were brushed with a commercial electric toothbrush with the dentifrices. VSI quantified the mean roughness (Ra) and illustrated in 3D the abraded areas. Results Toothpastes induced a limited abrasion. Toothpowders induced a significantly higher roughness linked to the size of the abrasive particles. One powder (Gencix® produced a high abrasion when used with a standard testing weight. However, the powder is based on pumice particles covered by a plant homogenate that readily dissolves in water. When used in the same volume, or after dispersion in water, Ra was markedly reduced. Conclusion Light and electron microscopy characterize the abrasive particles and VSI is a new tool allowing the analysis of large surface of abraded materials. PMID:24212995

  11. Sand abrasion injury and biomass partitioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind blown soil particle abrasion negatively impacts millions of hectares of crops annually. The goal of this study was to examine the effects of wind and wind blown sand abrasion damage on cotton (Gossypium hirsutum L.) seedling biomass partitioning to leaves, stems, and roots. Seedlings of three ...

  12. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... of the American National Standard Safety Code for the Use, Care, and Protection of Abrasive Wheels... Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.215 Abrasive wheel machinery....

  13. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... of the American National Standard Safety Code for the Use, Care, and Protection of Abrasive Wheels... Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.215 Abrasive wheel machinery....

  14. Cotton seedling abrasion and recovery from wind blown sand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of hectares of crops are exposed to wind blown sand abrasion each year and in many instances the damage is thought to be severe enough to require replanting. The goal of this study was to determine the effects of wind blown sand abrasion duration on cotton (Gossypium hirsutum L.) seedlings...

  15. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 5 2010-07-01 2010-07-01 false Abrasive wheel machinery. 1910.215 Section 1910.215 Labor... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.215 Abrasive wheel machinery. (a... wheel in motion. (5) Excluded machinery. Natural sandstone wheels and metal, wooden, cloth, or...

  16. Sand abrasion injury and biomass partitioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of acres of crops are exposed to wind blown sand abrasion injury each year and in many instances the damage is thought to be sufficiently severe to require replanting. The goal of this study was to determine the effects of wind blown sand abrasion duration on cotton seedlings. Seedlings of ...

  17. Unstable periodic orbits in human epileptic hippocampal slices.

    PubMed

    Pen-Ning Yu; Min-Chi Hsiao; Dong Song; Liu, Charles Y; Heck, Christi N; Millett, David; Berger, Theodore W

    2014-01-01

    Inter-ictal activity is studied in hippocampal slices resected from patients with epilepsy using local field potential recording. Inter-ictal activity in the dentate gyrus (DG) is induced by high-potassium (8 mM), low-magnesium (0.25 mM) aCSF with additional 100 μM 4-aminopyridine(4-AP). The dynamics of the inter-ictal activity is investigated by developing the first return map with inter-pulse intervals. Unstable periodic orbits (UPOs) are detected in the hippocampal slice at the DG area according to both the topological recurrence method and the periodic orbit transform method. Surrogate analysis suggests the presence of UPOs in hippocampal slices from patients with epilepsy. This finding also suggests that inter-ictal activity is a chaotic system and will allow us to apply chaos control techniques to manipulate inter-ictal activity. PMID:25571314

  18. Studying T Cell Development in Thymic Slices.

    PubMed

    Ross, Jenny O; Melichar, Heather J; Halkias, Joanna; Robey, Ellen A

    2016-01-01

    Recently, tissue slices have been adapted to study both mouse and human T cell development. Thymic slices combine and complement the strengths of existing organotypic culture systems to study thymocyte differentiation. Specifically, the thymic slice system allows for high throughput experiments and the ability to introduce homogenous developmental intermediate populations into an environment with a well-established cortex and medulla. These qualities make thymic slices a highly versatile and technically accessible model to study thymocyte development. Here we describe methods to prepare, embed, and slice thymic lobes to study T cell development in situ. PMID:26294404

  19. Abrasive wear behavior of P/M titanium metal-matrix composites

    SciTech Connect

    Alman, D.E.; Hawk, J.A.; Simmons, J.W.

    1997-01-01

    The abrasive wear behavior of titanium metal-matrix composites produced by powder metallurgical techniques was studied. Ti powder was mixed with 0, 20, or 40 volume percent (v%) TiB2, TiC, TiN, SiC, an B4C powder to produce a composite powder blend. The blends were consolidated by hot-pressing at 1200° C and 20 MPa for 2 hours. Also a series of Ti-TiB2 composites was consolidated by press and sinter techniques. Two-body abrasive wear resistance, of the composites worn against either SiC or garnet particles, was evaluated using a pin-on-drum apparatus. The wear behavior of the composites was correlated to the physical properties (e.g., microstructure, sintered density, hardness, strength) of the composites, and compared to the behavior of conventional cast adn wrought Ti and other alloys.

  20. Microfracture patterns of abrasive wear striations on teeth indicate directionality.

    PubMed

    Gordon, K R

    1984-03-01

    A method is described that will indicate the direction that an abrasive particle was traveling as it scored the surface of a brittle material. Light and scanning electron micrographs of glass, dentine, and enamel abraded by loose and, steel carbide, and diamond indicate that partial Hertzian fracture cones are formed at the margins of wear striations during abrasion. The bases of these fracture cones face in the direction of travel of the abrasive particle and, therefore, indicate directionality. Because this method is based only on the consistent geometry of fracturing of brittle materials, it is independent of the loading of the abrasive particle. The only other method available to determine directionality of striations is unreliable since it uses the width of striations, and, hence, is dependent upon a consistent loading regime of the abrasive particle. This new method has direct application for determining the direction of movement of the jaws during mastication in living or fossil animals. PMID:6731603

  1. Solidification Structure and Abrasion Resistance of High Chromium White Irons

    SciTech Connect

    Dogan, O.N.; Hawk, J.A.; Laird, George, II

    1997-06-01

    Superior abrasive wear resistance, combined with relatively low production costs, makes high Cr white cast irons (WCIs) particularly attractive for applications in the grinding, milling, and pumping apparatus used to process hard materials. Hypoeutectic, eutectic, and hypereutectic cast iron compositions, containing either 15 or 26 wt pct chromium, were studied with respect to the macrostructural transitions of the castings, solidification paths, and resulting microstructures when poured with varying superheats. Completely equiaxed macrostructures were produced in thick section castings with slightly hypereutectic compositions. High-stress abrasive wear tests were then performed on the various alloys to examine the influence of both macrostructure and microstructure on wear resistance. Results indicated that the alloys with a primarily austenitic matrix had a higher abrasion resistance than similar alloys with a pearlitic/bainitic matrix. Improvement in abrasion resistance was partially attributed to the ability of the austenite to transform to martensite at the wear surface during the abrasion process.

  2. Solidification structure and abrasion resistance of high chromium white irons

    SciTech Connect

    Dogan, O.N.; Hawk, J.A.; Laird, G. II

    1997-06-01

    Superior abrasive wear resistance, combined with relatively low production costs, makes high Cr white cast irons (WCIs) particularly attractive for applications in the grinding, milling, and pumping apparatus used to process hard materials. Hypoeutectic, eutectic, and hypereutectic cast iron compositions, containing either 15 or 26 wt pct chromium, were studied with respect to the macrostructural transitions of the castings, solidification paths, and resulting microstructures when poured with varying superheats. Completely equiaxed macrostructures were produced in thick section castings with slightly hypereutectic compositions. High-stress abrasive wear tests were then performed on the various alloys to examine the influence of both macrostructure and microstructure on wear resistance. Results indicated that the alloys with a primarily austenitic matrix had a higher abrasion resistance than similar alloys with a pearlitic/bainitic matrix. Improvement in abrasion resistance was partially attributed to the ability of the austenite to transform to martensite at the wear surface during the abrasion process.

  3. Automatic basal slice detection for cardiac analysis

    NASA Astrophysics Data System (ADS)

    Paknezhad, Mahsa; Marchesseau, Stephanie; Brown, Michael S.

    2016-03-01

    Identification of the basal slice in cardiac imaging is a key step to measuring the ejection fraction (EF) of the left ventricle (LV). Despite research on cardiac segmentation, basal slice identification is routinely performed manually. Manual identification, however, has been shown to have high inter-observer variability, with a variation of the EF by up to 8%. Therefore, an automatic way of identifying the basal slice is still required. Prior published methods operate by automatically tracking the mitral valve points from the long-axis view of the LV. These approaches assumed that the basal slice is the first short-axis slice below the mitral valve. However, guidelines published in 2013 by the society for cardiovascular magnetic resonance indicate that the basal slice is the uppermost short-axis slice with more than 50% myocardium surrounding the blood cavity. Consequently, these existing methods are at times identifying the incorrect short-axis slice. Correct identification of the basal slice under these guidelines is challenging due to the poor image quality and blood movement during image acquisition. This paper proposes an automatic tool that focuses on the two-chamber slice to find the basal slice. To this end, an active shape model is trained to automatically segment the two-chamber view for 51 samples using the leave-one-out strategy. The basal slice was detected using temporal binary profiles created for each short-axis slice from the segmented two-chamber slice. From the 51 successfully tested samples, 92% and 84% of detection results were accurate at the end-systolic and the end-diastolic phases of the cardiac cycle, respectively.

  4. Design of an impact abrasion testing machine

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Beeley, P. R.; Baker, A. J.

    1994-04-01

    By using a cam-flat follower-impact shaft with a crank-flat rotating anvil system, the machine to be described can create various impact abrasion conditions to simulate a large range of industrial situations encountered in this field. The main features of the machine are the long working life of the flat rotating anvil, which works in the same way as that of the disk in a pin-on-disk wear tester, and the accurate control of both the impact energy delivered to the specimen and the total sliding distance of the specimen on the anvil. Statistical analysis of test results on the machine with EN24 steel and cast high manganese steel shows that the uncertainty of the population mean is within +/- 4.7% of the sample mean under a 95% confidence level of student distribution, which indicates a very good accuracy of test.

  5. Slicing AADL Specifications for Model Checking

    NASA Technical Reports Server (NTRS)

    Odenbrett, Maximilian; Nguyen, Viet Yen; Noll, Thomas

    2010-01-01

    To combat the state-space explosion problem in model checking larger systems, abstraction techniques can be employed. Here, methods that operate on the system specification before constructing its state space are preferable to those that try to minimize the resulting transition system as they generally reduce peak memory requirements. We sketch a slicing algorithm for system specifications written in (a variant of) the Architecture Analysis and Design Language (AADL). Given a specification and a property to be verified, it automatically removes those parts of the specification that are irrelevant for model checking the property, thus reducing the size of the corresponding transition system. The applicability and effectiveness of our approach is demonstrated by analyzing the state-space reduction for an example, employing a translator from AADL to Promela, the input language of the SPIN model checker.

  6. Particle size effects on the abrasive wear of 20 vol% SiC{sub p}/7075Al composites

    SciTech Connect

    Sheu, C.Y.; Lin, S.J.

    1996-12-01

    Discontinuously reinforced aluminum (DRA) composites have many advantages over the unreinforced aluminum alloys and have found increasing applications in the automotive industry. The wear behavior plays a very important role in DRA composites for such applications. The commonly used apparatus for studying the DRA abrasive wear include pin-on-disk, block-on-ring, and pin-on-drum. The pins or blocks are the composites and the abrasive papers are bonded onto the counter parts. The main drawback of the block-on-ring and pin-on-drum techniques is that the contact area does not remain a constant during the initial testing period. In the pin-on-disk method, the abrasive testing conditions are not easily kept identical either. The abrasive particles are prone to be blunted and smeared by composites when running a single-track test and the sliding speed is not constant when running a spiral-track test. In this study, a modified pin-on-disk apparatus was developed. During the entire testing period, the contact area remains unchanged, and the composite pin can be always abraded y fresh abrasive particles. An aluminum alloy, AA 7075 was reinforced with 20 vol% SiC{sub p} at various particle sizes (82, 59, 37, 16, and 12 {micro}m).

  7. Mechanics, kinematics and geometry of pebble abrasion from binary collisions

    NASA Astrophysics Data System (ADS)

    Miller, K. L.; Jerolmack, D. J.

    2014-12-01

    As sediment is transported downstream as bedload, it collides with the bed causing sharp edges to chip and wear away, rounding the rock through the process of abrasion. Previous work has linked abrasion to downstream fining and rounding of grains, however, there has been little attempt to understand the underlying kinematics of abrasion. Furthermore, most studies neglect the fine particle produced during the abrasion process, as the initial grain gets smaller and rounder. In this research, we preform well-controlled laboratory experiments to determine the functional dependence between impact energy and mass lost from abrasion. We use a double-pendulum "Newton's Cradle" set-up to examine the abrasion between two grains and with a high-speed camera, we can quantify the impact energies during collision. Results from experiments verify that mass loss is proportional to kinetic energy. We define a material parameter that incorporates material density, Young's modulus, and tensile stress and show that this parameter is directly related to the proportionality between mass loss and energy. We identify an initial region of the mass loss curves in which abrasion is independent of energy and material properties; results suggest this region is determined by shape. We show that grain size distributions of daughter products are universal and independent of material; they follow a Weibull distribution, which is expected distribution from brittle fracture theory. Finally, scanning electron microscope (SEM) images show a thin damage zone near the surface, suggesting that collision energy is attenuated over some small skin depth. Overall, we find that pebble abrasion by collision can be characterized by two universal scaling relations - the mass loss versus energy curves and the size distribution of daughter products. Results will be useful for estimating expected abrasion rates in the field, and additionally demonstrate that low-energy collisions produce large quantities of sand

  8. ERTS-1 image enhancement by optically combining density slices

    NASA Technical Reports Server (NTRS)

    Tapper, G. O.; Pease, R. W.

    1973-01-01

    The technique of density slicing using a photographic film and its application to enhancement of ERTS-1 imagery has proved to be useful for mapping varigated areal phenomena and provides a useful supplement ot the I2S MiniAddcol viewing system. The intial experiments conducted with this film were encouraging, and indicated that this technique of density slicing using readily accessible darkroom facilities and simple darkroom procedures allows rapid, accurate, and facile interpretation of certain areal phenomena to be made from the imagery. The distribution of the tree yucca, Yucca brevifolia Jaegeriana, in the eastern Mojave Desert of Southern California and southern Nevada was used as an example to test the accuracy of the technique for mapping purposes. The distribution was mapped at a relatively high level of accuracy.

  9. The effects of abrasives on electrical submersible pumps

    SciTech Connect

    Wilson, B.L. )

    1990-06-01

    The electrical submersible pump (ESP) is a high-speed rotating device. Its operational life in oil wells can depend on the type and quantities of abrasives present in the produced fluid. This paper reports on a set of experiments performed in a specialized abrasive test loop. In the test, the size and quantity of abrasives were varied along with flow rate through the pump. This paper also examines recent literature on sand production and explores some of the practical problems in sand measurement.

  10. Method for forming an abrasive surface on a tool

    DOEpatents

    Seals, Roland D.; White, Rickey L.; Swindeman, Catherine J.; Kahl, W. Keith

    1999-01-01

    A method for fabricating a tool used in cutting, grinding and machining operations, is provided. The method is used to deposit a mixture comprising an abrasive material and a bonding material on a tool surface. The materials are propelled toward the receiving surface of the tool substrate using a thermal spray process. The thermal spray process melts the bonding material portion of the mixture, but not the abrasive material. Upon impacting the tool surface, the mixture or composition solidifies to form a hard abrasive tool coating.

  11. Lip rejuvenation using chemical abrasion and padding with expanded polytetrafluoroethylene implants.

    PubMed

    Mole, B

    1996-01-01

    Aesthetic improvement of the lips is a problem that must be treated in a totally independent way from the rest of the face because degeneration of the lips is tied to genetic or acquired factors for which no long-term procedure is effective. The effectiveness of resurfacing of large and small wrinkles using chemical abrasion has long been recognized. Labial padding, using supple Gore-Tex(R) implants that are cut to size and placed where necessary provides the desired result while preserving the function of the lip. Usually requested by the younger patient, it can be used in combination with chemical abrasion in the more mature patient. This technique is not only quick, tested, very effective, and definitive, but totally reversible if needed, which allows us to widen the indications with great safety. PMID:8670390

  12. The Relationship between the Microstructure and Abrasive Resistance of a Hardfacing Alloy in the Fe-Cr-C-Nb-V System

    NASA Astrophysics Data System (ADS)

    Correa, E. O.; Alcântara, N. G.; Tecco, D. G.; Kumar, R. V.

    2007-08-01

    The relationship between abrasive wear resistance and microstructure of a hardfacing alloy based on the Fe-Cr-C-Nb-V system was investigated. This material was developed for cladding, by an open arc welding technique, of components subjected to severe abrasive wear. The work undertaken included the solidification study, microstructural characterization, and abrasion testing. Microstructural examinations of hardfaced layer showed that the microstructure of the alloy consisted of a large volume fraction of primary niobium carbides randomly dispersed in a metastable austenitic matrix containing fine M3C carbides and “islands” of eutectic mixture of γ/M7C3. Energy dispersive X-ray analysis results showed that V preferentially partitioned into the NbC and M3C phases. In comparison with the conventional high carbon/high chromium hardfacing alloy with higher hardness, a Fe-Cr-C-Nb-V hardfacing alloy exhibited improved abrasive wear resistance and a microstructure with higher toughness.

  13. New Rock Abrasivity Test Method for Tool Life Assessments on Hard Rock Tunnel Boring: The Rolling Indentation Abrasion Test (RIAT)

    NASA Astrophysics Data System (ADS)

    Macias, F. J.; Dahl, F.; Bruland, A.

    2016-05-01

    The tunnel boring machine (TBM) method has become widely used and is currently an important presence within the tunnelling industry. Large investments and high geological risk are involved using TBMs, and disc cutter consumption has a great influence on performance and cost, especially in hard rock conditions. Furthermore, reliable cutter life assessments facilitate the control of risk as well as avoiding delays and budget overruns. Since abrasive wear is the most common process affecting cutter consumption, good laboratory tests for rock abrasivity assessments are needed. A new abrasivity test method by rolling disc named Rolling Indentation Abrasion Test (RIAT) has been developed. The goal of the new test design and procedure is to reproduce wear behaviour on hard rock tunnel boring in a more realistic way than the traditionally used methods. Wear by rolling contact on intact rock samples is introduced and several rock types, covering a wide rock abrasiveness range, have been tested by RIAT. The RIAT procedure indicates a great ability of the testing method to assess abrasive wear on rolling discs. In addition and to evaluate the newly developed RIAT test method, a comprehensive laboratory testing programme including the most commonly used abrasivity test methods and the mineral composition were carried out. Relationships between the achieved results from conventional testing and RIAT results have been analysed.

  14. Effect of abrasive grit size on wear of manganese-zinc ferrite under three-body abrasion

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1987-01-01

    Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and deformed layers produced in single-crystal Mn-Zn ferrites under three-body abrasion. The abrasion mechanism of Mn-Zn ferrite changes drastically with the size of abrasive grits. With 15-micron (1000-mesh) SiC grits, abrasion of Mn-Zn ferrite is due principally to brittle fracture; while with 4- and 2-micron (4000- and 6000-mesh) SiC grits, abrasion is due to plastic deformation and fracture. Both microcracking and plastic flow produce polycrystalline states on the wear surfaces of single-crystal Mn-Zn ferrites. Coefficient of wear, total thickness of the deformed layers, and surface roughness of the wear surfaces increase markedly with an increase in abrasive grit size. The total thicknesses of the deformed layers are 3 microns for the ferrite abraded by 15-micron SiC, 0.9 microns for the ferrite abraded by 4-micron SiC, and 0.8 microns for the ferrite abraded by 1-micron SiC.

  15. Abrasive jet micro-machining of polymeric materials

    NASA Astrophysics Data System (ADS)

    Hailu, Getu

    In the abrasive jet micro-machining (AJM) process, a jet of small particles is directed through an erosion resistant mask opening so that micro-sized features (i.e., micro-channels, holes, etc.) can be machined for the fabrication of micro-devices such as micro-fluidic and micro-electro-mechanical-systems (MEMS). Polymeric materials and elastomers have found applications in a wide variety of micro-devices. This thesis investigates the AJM of such materials, addressing the major challenges that must be overcome in order for the process to gain wider acceptance in industry. The thesis first presents a novel cryogenically assisted abrasive jet micro-machining (CAJM) technique that enables the micro-machining of elastomers such as polydimethylsiloxane (PDMS) that cannot be machined at room temperature. It was found that the erosion rate during CAJM is greatly increased, and the degree of particle embedment greatly decreased, compared to room temperature experiments. A finite element (FE) analysis was used to investigate the relationships between erosion, the heat transfer of the cooling jet and the resulting target temperature during the CAJM of channels in PDMS. The analysis illustrated the asymmetric nature of the cooling with much more cooling occurring towards the trailing edge of the jet. It was found that the predicted shape of the evolving machined surface profiles was improved significantly when a FE model was used to account for thermal distortion occurring during the CAJM process. An unwanted consequence of the AJM of polymeric materials was found to be particle embedding. Criteria leading to the embedding of spherical and angular particles in such materials were identified and modelled using rigid plastic analyses. It was found that the likelihood of embedding was proportional to the static coefficient of friction between the particle and the target for angular particles, and the depth of penetration for spherical particles. Scanning electron microscopy with

  16. Synchronized slice viewing of similar image series

    NASA Astrophysics Data System (ADS)

    Ali, Sharib; Foncubierta, Antonio; Depeursinge, Adrien; Meriaudeau, Fabrice; Ratib, Osman; Müller, Henning

    2012-02-01

    Comparing several series of images is not always easy as the corresponding slices often need to be selected manually. In times where series contain an ever-increasing number of slices this can mean manual work when moving several series to the corresponding slice. Particularly two situations were identified in this context: (1) patients with a large number of image series over time (such as patients with cancers that are monitored) frequently need to compare the series, for example to compare tumor growth over time. Manually adapting two series is possible but with four or more series this can mean loosing time. Having automatically the closest slice by comparing visual similarity also in older series with differing slice thickness and inter slice distance can save time and synchronize the viewing instantly. (2) analyzing visually similar image series of several patients can profit from being viewed in a synchronized way to compare the cases, so when sliding through the slices in one volume, the corresponding slices in the other volumes are shown. This application could be employed after content-based 3D image retrieval has found similar series, for example. Synchronized viewing can help finding or confirming the most relevant cases quickly. To allow for synchronized viewing of several image volumes, the test image series are first registered applying affine transformation for the global registration of images followed by diffeomorphic image registration. Then corresponding slices in the two volumes are estimated based on a visual similarity. Once the registration is finished, the user can subsequently move inside the slices of one volume (reference volume) and can view the corresponding slices in the other volumes. These corresponding slices are obtained after a correspondence match in the registration procedure. These volumes are synchronized in that the slice closest to the original reference volume is shown even when the slice thicknesses or inter slice

  17. Improved wound healing in blue LED treated superficial abrasions

    NASA Astrophysics Data System (ADS)

    Rossi, Francesca; Tatini, Francesca; Pini, Roberto; Bacci, Stefano; De Siena, Gaetano; Cicchi, Riccardo; Pavone, Francesco; Alfieri, Domenico

    2013-06-01

    A blue-LED photocoagulator device was designed in order to induce a selective photocoagulation effect in superficial bleeding. An in vivo study in rat back skin evidenced an improved healing process in the LED treated abrasions.

  18. Resistance of dentin coating materials against abrasion by toothbrush.

    PubMed

    Gando, Iori; Ariyoshi, Meu; Ikeda, Masaomi; Sadr, Alireza; Nikaido, Toru; Tagami, Junji

    2013-01-01

    Thin-film coating of root dentin surface by all-in-one adhesives has been shown to be an effective option to prevent root surface caries. The purpose of this study was to investigate the wear resistance against toothbrush abrasion of two all-in-one coating materials; Shield Force (SF) and Hybrid Coat (HC). Bovine dentin surfaces were covered with one of the coating materials; SF or HC. After storage in water for 24 h, the testing surface was subjected to the toothbrush abrasion test up to 50,000 cycles either in water or toothpaste slurry. The remaining thickness of the coating material was measured using SEM. Toothpaste slurry significantly increased rate of tooth brush abrasion of the coating materials. While SF and HC wore at a similar pace under toothbrush abrasion, SF had a thicker coat and could protect dentin longer, up to 50,000 cycles. PMID:23370872

  19. Dentifrice fluoride and abrasivity interplay on artificial caries lesions.

    PubMed

    Nassar, Hani M; Lippert, Frank; Eckert, George J; Hara, Anderson T

    2014-01-01

    Incipient caries lesions on smooth surfaces may be subjected to toothbrushing, potentially leading to remineralization and/or abrasive wear. The interplay of dentifrice abrasivity and fluoride on this process is largely unknown and was investigated on three artificially created lesions with different mineral content/distribution. 120 bovine enamel specimens were randomly allocated to 12 groups (n = 10), resulting from the association of (1) lesion type [methylcellulose acid gel (MeC); carboxymethylcellulose solution (CMC); hydroxyethylcellulose gel (HEC)], (2) slurry abrasive level [low (REA 4/ RDA 69); high (REA 7/RDA 208)], and (3) fluoride concentration [0/275 ppm (14.5 mM) F as NaF]. After lesion creation, specimens were brushed in an automated brushing machine with the test slurries (50 strokes 2×/day). Specimens were kept in artificial saliva in between brushings and overnight. Enamel surface loss (SL) was determined by optical profilometry after lesion creation, 1, 3 and 5 days. Two enamel sections (from baseline and post-brushing areas) were obtained and analyzed microradiographically. Data were analyzed by analysis of variance and Tukey's tests (α = 5%). Brushing with high-abrasive slurry caused more SL than brushing with low-abrasive slurry. For MeC and CMC lesions, fluoride had a protective effect on SL from day 3 on. Furthermore, for MeC and CMC, there was a significant mineral gain in the remaining lesions except when brushed with high-abrasive slurries and 0 ppm F. For HEC, a significant mineral gain took place when low-abrasive slurry was used with fluoride. The tested lesions responded differently to the toothbrushing procedures. Both slurry fluoride content and abrasivity directly impacted SL and mineral gain of enamel caries lesions. PMID:24993884

  20. A slice of the universe

    NASA Technical Reports Server (NTRS)

    De Lapparent, V.; Geller, M. J.; Huchra, J. P.

    1986-01-01

    A preliminary discussion is presented of recent results obtained as part of the extension of the Center of Astrophysics redshift survey. Several features of the results are striking. The distribution of galaxies in the sample, which contains 1100 galaxies in a 6 deg x 117 deg strip going through the Coma cluster, looks like a slice through the suds in the kitchen sink. It appears that the galaxies are on the surfaces of bubble-like structures with diameters of 25-50/h-Mpc. The largest bubble in the survey has a diameter comparable with the most recent estimates of the diameter of the void in Bootes. This topology poses serious challenges for current models for the formation of large-scale structure. The best available model for generating these structures is the explosive galaxy formation theory of Ostriker and Cowie (1981).

  1. Method of protecting surfaces from abrasion and abrasion resistant articles of manufacture

    DOEpatents

    Hirschfeld, T.B.

    1988-06-09

    Surfaces of fabricated structures are protected from damage by impacting particulates by a coating of hard material formed as a mass of thin flexible filaments having root ends secured to the surface and free portions which can flex and overlap to form a resilient cushioning mat which resembles hair or fur. The filamentary coating covers the underlying surface with hard abrasion resistance material while also being compliant and capable of local accommodation to particle impacts. The coating can also function as thermal and/or acoustical insulation and has a friction reducing effect. 11 figs.

  2. Atmospheric particulate emissions from dry abrasive blasting using coal slag.

    PubMed

    Kura, Bhaskar; Kambham, Kalpalatha; Sangameswaran, Sivaramakrishnan; Potana, Sandhya

    2006-08-01

    Coal slag is one of the widely used abrasives in dry abrasive blasting. Atmospheric emissions from this process include particulate matter (PM) and heavy metals, such as chromium, lead, manganese, nickel. Quantities and characteristics of PM emissions depend on abrasive characteristics and process parameters. Emission factors are key inputs to estimate emissions. Experiments were conducted to study the effect of blast pressure, abrasive feed rate, and initial surface contamination on total PM (TPM) emission factors for coal slag. Rusted and painted mild steel surfaces were used as base plates. Blasting was carried out in an enclosed chamber, and PM was collected from an exhaust duct using U.S. Environment Protection Agency source sampling methods for stationary sources. Results showed that there is significant effect of blast pressure, feed rate, and surface contamination on TPM emissions. Mathematical equations were developed to estimate emission factors in terms of mass of emissions per unit mass of abrasive used, as well as mass of emissions per unit of surface area cleaned. These equations will help industries in estimating PM emissions based on blast pressure and abrasive feed rate. In addition, emissions can be reduced by choosing optimum operating conditions. PMID:16933653

  3. Atmospheric particulate emissions from dry abrasive blasting using coal slag

    SciTech Connect

    Bhaskar Kura; Kalpalatha Kambham; Sivaramakrishnan Sangameswaran; Sandhya Potana

    2006-08-15

    Coal slag is one of the widely used abrasives in dry abrasive blasting. Atmospheric emissions from this process include particulate matter (PM) and heavy metals, such as chromium, lead, manganese, nickel. Quantities and characteristics of PM emissions depend on abrasive characteristics and process parameters. Emission factors are key inputs to estimate emissions. Experiments were conducted to study the effect of blast pressure, abrasive feed rate, and initial surface contamination on total PM (TPM) emission factors for coal slag. Rusted and painted mild steel surfaces were used as base plates. Blasting was carried out in an enclosed chamber, and PM was collected from an exhaust duct using U.S. Environment Protection Agency source sampling methods for stationary sources. Results showed that there is significant effect of blast pressure, feed rate, and surface contamination on TPM emissions. Mathematical equations were developed to estimate emission factors in terms of mass of emissions per unit mass of abrasive used, as well as mass of emissions per unit of surface area cleaned. These equations will help industries in estimating PM emissions based on blast pressure and abrasive feed rate. In addition, emissions can be reduced by choosing optimum operating conditions. 40 refs., 5 figs., 2 tabs.

  4. Analysis of Abrasive Blasting of DOP-26 Iridium Alloy

    SciTech Connect

    Ohriner, Evan Keith; Zhang, Wei; Ulrich, George B

    2012-01-01

    The effects of abrasive blasting on the surface geometry and microstructure of DOP-26 iridium alloy (Ir-0.3% W-0.006% Th 0.005% Al) have been investigated. Abrasive blasting has been used to control emissivity of components operating at elevated temperature. The effects of abrasive blasting conditions on surface morphology were investigated both experimentally and by numerical modeling. The simplified model, based on finite element analysis of a single angular particle impacting on Ir alloy disk, calculates the surface deformation and residual strain distribution. The experimental results and modeling results both indicate that the surface geometry is not sensitive to the abrasive blast process conditions of nozzle pressure and standoff distance considered in this study. On the other hand, the modeling results suggest that the angularity of the abrasive particle has an important role in determining surface geometry, which in turn, affects the emissivity. Abrasive blasting causes localized surface strains and localized recrystallization, but it does not affect grain size following extended exposure at elevated temperature. The dependence of emissivity of the DOP-26 alloy on mean surface slope follows a similar trend to that reported for pure iridium.

  5. Experimental Study on Abrasive Waterjet Polishing of Hydraulic Turbine Blades

    NASA Astrophysics Data System (ADS)

    Khakpour, H.; Birglenl, L.; Tahan, A.; Paquet, F.

    2014-03-01

    In this paper, an experimental investigation is implemented on the abrasive waterjet polishing technique to evaluate its capability in polishing of surfaces and edges of hydraulic turbine blades. For this, the properties of this method are studied and the main parameters affecting its performance are determined. Then, an experimental test-rig is designed, manufactured and tested to be used in this study. This test-rig can be used to polish linear and planar areas on the surface of the desired workpieces. Considering the number of parameters and their levels, the Taguchi method is used to design the preliminary experiments. All experiments are then implemented according to the Taguchi L18 orthogonal array. The signal-to-noise ratios obtained from the results of these experiments are used to determine the importance of the controlled polishing parameters on the final quality of the polished surface. The evaluations on these ratios reveal that the nozzle angle and the nozzle diameter have the most important impact on the results. The outcomes of these experiments can be used as a basis to design a more precise set of experiments in which the optimal values of each parameter can be estimated.

  6. Experimental investigation of the abrasive crown dynamics in orbital atherectomy.

    PubMed

    Zheng, Yihao; Belmont, Barry; Shih, Albert J

    2016-07-01

    Orbital atherectomy is a catheter-based minimally invasive procedure to modify the plaque within atherosclerotic arteries using a diamond abrasive crown. This study was designed to investigate the crown motion and its corresponding contact force with the vessel. To this end, a transparent arterial tissue-mimicking phantom made of polyvinyl chloride was developed, a high-speed camera and image processing technique were utilized to visualize and quantitatively analyze the crown motion in the vessel phantom, and a piezoelectric dynamometer measured the forces on the phantom during the procedure. Observed under typical orbital atherectomy rotational speeds of 60,000, 90,000, and 120,000rpm in a 4.8mm caliber vessel phantom, the crown motion was a combination of high-frequency rotation at 1000, 1500, and 1660.4-1866.1Hz and low-frequency orbiting at 18, 38, and 40Hz, respectively. The measured forces were also composed of these high and low frequencies, matching well with the rotation of the eccentric crown and the associated orbital motion. The average peak force ranged from 0.1 to 0.4N at different rotational speeds. PMID:27160429

  7. Microstructure and Abrasive Wear Performance of Ni-Wc Composite Microwave Clad

    NASA Astrophysics Data System (ADS)

    Bansal, Amit; Zafar, Sunny; Sharma, Apurbba Kumar

    2015-10-01

    In the present work, Ni-WC powder was deposited on mild steel substrate to develop clads through microwave hybrid heating technique. The cladding trials were carried out in an industrial microwave applicator at 1.1 kW for 540 s. The Ni-WC composite clads were characterized for microstructure and abrasive wear performance through combination of x-ray diffraction, electron and optical microscopy, microhardness, and wear tests. Phase analysis of the Ni-WC clad indicated the presence of stable carbides such as WC, W2C, Ni2W4C, and Fe6W6C. The microstructure study of the clad layer revealed the presence of a uniformly distributed interlocked WC-based reinforcement embedded in the Ni-based matrix. The average Vicker's microhardness in the clad layer was observed to be 1028 ± 90 HV, which was approximately three times the microhardness of the substrate. Abrasive wear resistance of the microwave clads was superior to the MS substrate. Abrasion was the main wear mechanism in the Ni-WC clads and the substrate samples. However, the presence of WC-based reinforcement in the composite clads reduced microcutting, resulting in enhanced wear resistance.

  8. MODELLING TRANSFER OF LISTERIA MONOCYTOGENES DURING SLICING OF "GRAVAD" SALMON

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transfer of a rifampicin-resistant mutant of Listeria monocytogenes strain F2365 from an inoculated slicing blade to slices of gravad salmon (Salmo salar), and from inoculated salmon fillet to the slicing machine and subsequently to slices of uninoculated fillet was studied. The effect of slicing te...

  9. A modified ASTM G-75 abrasion test helps select candidate alloys for service in a corrosive and abrasive slurry

    SciTech Connect

    Corbett, R.A.; Morrison, W.S.; Jenkins, C.F.; Westinghouse Savannah River Co., Aiken, SC )

    1989-01-01

    The design of a hazardous waste immobilization facility at the Savannah River Site (SRS) set material requirements for both abrasion resistance and corrosion resistance in process equipment. Standard ASTM slurry wear test G75 was modified to permit evaluation and comparison of abrasive resistance of candidate materials of construction in the laboratory. However, corrosion was found to contribute significantly to overall metal loss during the testing. Consequently, the abrasive slurry used for the testing was modified by adjusting its chemistry to include appropriate corrosive species. The Miller numbers obtained in the modified G75 Miller abrasion test are described. Pilot plant observations for Type 304L austenitic stainless steel were available. These data were used to generate a Morrison-Miller Ratio'' in order to determine anticipated field abrasion properties for other alloys. Hardness for many of the alloys fell in a narrow range about Rockwell B90, but performance varied significantly in response to slurry chemistry. This effect if synergistic may often be overlooked in the selection process, and it needs to be addressed. Some pilot plant testing of other alloys is essential to confirm the calculated abrasion rates and the approach of using the Morrison-Miller ratio. 6 refs., 3 figs., 5 tabs.

  10. Weldability of an abrasion-resistant steel

    SciTech Connect

    Adonyi, Y.; Domis, W.F.; Chen, C.C.

    1995-12-31

    The welding performance of a low-carbon-equivalent, abrasion-resistant steel newly developed for the mining industry was studied using a combination of simulative and actual weldability tests. The susceptibility to hydrogen-induced cracking in the weld-metal and heat-affected zones (HAZ), as well as the potential loss of strength and toughness in the HAZ, were evaluated. Simulative testing included the use of the Gleeble 1500 thermomechanical simulator to produce single and multiple-pass weld HAZ microstructures on CVN-size specimens. The effects of heat input, interpass temperature, and post-weld heat treatment (PWHT) on the HAZ microstructure and properties were determined. Additionally, a computer software was used to predict theoretical HAZ hardnesses and volume fraction of phases as a function of cooling rates. The actual welding tests included the Gapped Bead-on-Plate and the Y-groove tests to determine the weld-metal and HAZ susceptibility to hydrogen-induced cracking. Three heat inputs, two diffusible hydrogen and two weld-metal yield-strength levels were used for the actual welding stage. Good correlation was found between microstructure predictions, physical simulations, and actual weld testing results. The new steel was found to be highly weldable because of the low preheat required to avoid HAZ hydrogen induced cracking. All aspects of weld-metal and HAZ cracking behavior had to be addressed for a complete weldability characterization. It was also found that use of excessive heat inputs and PWHT should be avoided when welding this type of steels.

  11. The luminosity function for the CfA redshift survey slices

    NASA Technical Reports Server (NTRS)

    De Lapparent, Valerie; Geller, Margaret J.; Huchra, John P.

    1989-01-01

    The luminosity function for two complete slices of the extension of the CfA redshift survey is calculated. The nonparametric technique of Lynden-Bell (1971) and Turner (1979) is used to determine the shape for the luminosity function of the 12 deg slice of the redshift survey. The amplitude of the luminosity function is determined, taking large-scale inhomogeneities into account. The effects of the Malmquist bias on a magnitude-limited redshift survey are examined, showing that the random errors in the magnitudes for the 12 deg slice affect both the determination of the luminosity function and the spatial density constrast of large scale structures.

  12. Visible human slice sequence animation Web server

    NASA Astrophysics Data System (ADS)

    Bessaud, Jean-Christophe; Hersch, Roger D.

    2000-12-01

    Since June 1998, EPFL's Visible Human Slice Server (http://visiblehuman.epfl.ch) allows to extract arbitrarily oriented and positioned slices. More than 300,000 slices are extracted each year. In order to give a 3D view of anatomic structures, a new service has been added for extracting slice animations along a user-defined trajectory. This service is useful both for research and teaching purposes (http:visiblehuman.epfl.ch/animation/). Extracting slices of animations at any desired position and orientation from the Visible Human volume (Visible Man or Woman) requires both high throughput and much processing power. The I/O disk bandwidth can be increased by accessing more than one disk at the same time, i.e. by stripping data across several disks and by carrying out parallel asynchronous disk accesses. Since processing operations such as slice and animation extraction are compute- intensive, they require the program execution to be carried out in parallel on several computers. In the present contribution, we describe the new slice sequence animation service as well as the approach taken for parallelizing this service on a multi-PC multi-disk Web server.

  13. Rock Abrasion Tool Exhibits the Deep Red Pigment of Mars

    NASA Technical Reports Server (NTRS)

    2006-01-01

    During recent soil-brushing experiments, the rock abrasion tool on NASA's Mars Exploration Rover Spirit became covered with dust, as shown here. An abundance of iron oxide minerals in the dust gave the device a reddish-brown veneer. Investigators were using the rock abrasion tool to uncover successive layers of soil in an attempt to reveal near-surface stratigraphy. Afterward, remnant dirt clods were visible on both the bit and the brush of the tool. Designers of the rock abrasion tool at Honeybee Robotics and engineers at the Jet Propulsion Laboratory developed a plan to run the brush on the rock abrasion tool in reverse to dislodge the dirt and return the tool to normal operation. Subsequent communications with the rover revealed that the procedure is working and the rock abrasion tool remains healthy.

    Spirit acquired this approximately true-color image with the panoramic camera on the rover's 893rd sol, or Martian day (July 8, 2006). The image combines exposures taken through three of the camera's filters, centered on wavelengths of 750 nanometers, 530 nanometers, and 430 nanometers.

  14. Abrasive tip treatment for use on compressor blades

    NASA Technical Reports Server (NTRS)

    Pedersen, H. C.

    1984-01-01

    A co-spray process was used which simultaneously but separately introduces abrasive grits and metal matrix powder into the plasma stream and entraps the abrasive grits within a molten matrix to form an abrasive coating as the matrix material solidifies on test specimen surfaces. Spray trials were conducted to optimize spray parameter settings for the various matrix/grit combinations before actual spraying of the test specimens. Rub, erosion, and bond adhesion tests were conducted on the coated specimens in the as-sprayed condition as well as on coated specimens that were aged for 100 hours at a temperature of 866K (1100 F). Microscopic examinations were performed to determine the coating abrasive-particle content, the size and shape of the adhesive particles in the coating, and the extent of compositional or morphological changes resulting from the aging process. A nickel chromium/aluminum composite with No. 150 size (0.002 to 0.005 inch) silicon carbide grits was selected as the best matrix/abrasive combination of the candidates surveyed for coating compressor blade tips.

  15. Slice imaging of photodissociation of spatially oriented molecules

    SciTech Connect

    Lipciuc, M. Laura; Brom, Alrik J. van den; Dinu, Laura; Janssen, Maurice H.M.

    2005-12-15

    An electrostatic ion lens to spatially orient parent molecules and to image the angular distribution of photofragments is presented. Photodissociation of laboratory-oriented molecules makes it possible to study the dynamics of the dissociation process in more detail compared to photodissociation of nonoriented molecules. Using the velocity map imaging technique in combination with the slice imaging technique, the spatial recoil distribution of the photofragments can be measured with high resolution and without symmetry restrictions. Insertion of orientation electrodes between the repeller and the extractor of a velocity mapping electrostatic lens severely distorts the ion trajectories. The position where the ions are focused by the lens, the focal length, can be very different in the directions parallel and perpendicular to the inserted orientation electrodes. The focal length depends on the exact dimensions and positions of the electrodes of the ion lens. As this dependence is different in both directions, this dependence can be used to correct for the distorted ion trajectories. We discuss the design of an electrostatic ion lens, which is able to orient parent molecules and map the velocity of the photofragments. We report sliced images of photofragments from photolysis of spatially oriented CD{sub 3}I molecules to demonstrate the experimental combination of molecular orientation and velocity map slice imaging with good resolution.

  16. Class III Restoration of Anterior Primary Teeth: In Vitro Retention Comparison of Conventional, Modified and Air-abrasion Treated Preparations

    PubMed Central

    Asl Aminabadi, Naser; Najafpour, Ebrahim; Erfanparast, Leila; Samiei, Mohammad; Haghifar, Monireh; Sighari Deljavan, Alireza; Jamali, Zahra; Pournaghi Azar, Fatemeh; Shokravi, Marzieh

    2014-01-01

    Background and aims. Anterior esthetic restoration is challenging in pediatric dentistry, due to limited durability and poor retention of the restoration.This study assessed the effect of air abrasion on tensile failure load of composite class III restorations using different preparation techniques. Materials and methods. 100 extracted human anterior primary teeth were divided, based on the preparation methods, into four groups each consisting of 25 subjects : conventional (A), labial surface bevel (B), conventional + air abrasion (C), and labial surface bevel + air abrasion (D). After restoring cavities, tensile failure load of samples was measured in Newton by Universal testing machine at a crosshead speed of 1 mm per minute. The data were analyzed by Kruskal-Wallis and Mann Whitney U tests using SPSS software. Results. There were statistically significant differences between groups A and C (P = 0.003), groups A and B (P & 0.001), groups A and D (P & 0.001), groups B and C (P = 0.028), groups B and D (P = 0.027), and also groups C and D (P& 0.001). Group D demonstrated the highest mean tensile failure load. Conclusion. Labial surface bevel treated by air abrasion showed significantly more retention of composite restoration. PMID:25093052

  17. Measurement of the hyperelastic properties of tissue slices with tumour inclusion.

    PubMed

    O'Hagan, Joseph J; Samani, Abbas

    2008-12-21

    The elastic and hyperelastic properties of biological soft tissues have been of interest to the medical community as there are several applications where parameters characterizing these properties are critical for a reliable outcome. This includes applications such as surgery planning, needle biopsy and cancer diagnosis using medical imaging. While there has been considerable research on the measurement of the linear elastic modulus of small tissue samples, little research has been conducted for measuring parameters that characterize nonlinear elasticity of tissues included in slice specimens. In this paper, we present a method of measuring the hyperelastic parameters of tissue slice samples with tumours. In this method, to measure the hyperelastic properties of a tumour within a slice sample, the tumour was indented to acquire its force-displacement response while the slice remained intact. To calculate the hyperelastic parameters from the acquired data, we developed two inversion techniques that use the slice nonlinear finite element model as their forward problem solver. One of these techniques was based on nonlinear optimization while the other is a novel iterative technique that processes the variable slopes of the force-displacement response to calculate the hyperelastic parameters. The latter was developed specifically for the Yeoh and the second-order polynomial hyperelastic models, since we found that the other optimization-based inversion technique did not perform well with these models. To validate the proposed techniques, we performed numerical and phantom experiments. While we were able to achieve convergence with wide ranges of parameters of initial guesses to within 1% error with the numerical simulation experiments, we achieved convergence to within errors of around 5% with the tissue mimicking phantoms. Moreover, we successfully applied these techniques to data we acquired from nine pathological breast tissue slice specimens where the goal was to

  18. Measurement of the hyperelastic properties of tissue slices with tumour inclusion

    NASA Astrophysics Data System (ADS)

    O'Hagan, Joseph J.; Samani, Abbas

    2008-12-01

    The elastic and hyperelastic properties of biological soft tissues have been of interest to the medical community as there are several applications where parameters characterizing these properties are critical for a reliable outcome. This includes applications such as surgery planning, needle biopsy and cancer diagnosis using medical imaging. While there has been considerable research on the measurement of the linear elastic modulus of small tissue samples, little research has been conducted for measuring parameters that characterize nonlinear elasticity of tissues included in slice specimens. In this paper, we present a method of measuring the hyperelastic parameters of tissue slice samples with tumours. In this method, to measure the hyperelastic properties of a tumour within a slice sample, the tumour was indented to acquire its force-displacement response while the slice remained intact. To calculate the hyperelastic parameters from the acquired data, we developed two inversion techniques that use the slice nonlinear finite element model as their forward problem solver. One of these techniques was based on nonlinear optimization while the other is a novel iterative technique that processes the variable slopes of the force-displacement response to calculate the hyperelastic parameters. The latter was developed specifically for the Yeoh and the second-order polynomial hyperelastic models, since we found that the other optimization-based inversion technique did not perform well with these models. To validate the proposed techniques, we performed numerical and phantom experiments. While we were able to achieve convergence with wide ranges of parameters of initial guesses to within 1% error with the numerical simulation experiments, we achieved convergence to within errors of around 5% with the tissue mimicking phantoms. Moreover, we successfully applied these techniques to data we acquired from nine pathological breast tissue slice specimens where the goal was to

  19. Abrasion of Candidate Spacesuit Fabrics by Simulated Lunar Dust

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Meador, Mary Ann; Rogers, Kerry J.; Sheehy, Brennan H.

    2009-01-01

    A protocol has been developed that produced the type of lunar soil abrasion damage observed on Apollo spacesuits. This protocol was then applied to four materials (Kevlar (DuPont), Vectran (Kuraray Co., Ltd.), Orthofabric, and Tyvek (DuPont)) that are candidates for advanced spacesuits. Three of the four new candidate fabrics (all but Vectran) were effective at keeping the dust from penetrating to layers beneath. In the cases of Kevlar and Orthofabric this was accomplished by the addition of a silicone layer. In the case of Tyvek, the paper structure was dense enough to block dust transport. The least abrasive damage was suffered by the Tyvek. This was thought to be due in large part to its non-woven paper structure. The woven structures were all abraded where the top of the weave was struck by the abrasive. Of these, the Orthofabric suffered the least wear, with both Vectran and Kevlar suffering considerably more extensive filament breakage.

  20. Extending the viability of acute brain slices.

    PubMed

    Buskila, Yossi; Breen, Paul P; Tapson, Jonathan; van Schaik, André; Barton, Matthew; Morley, John W

    2014-01-01

    The lifespan of an acute brain slice is approximately 6-12 hours, limiting potential experimentation time. We have designed a new recovery incubation system capable of extending their lifespan to more than 36 hours. This system controls the temperature of the incubated artificial cerebral spinal fluid (aCSF) while continuously passing the fluid through a UVC filtration system and simultaneously monitoring temperature and pH. The combination of controlled temperature and UVC filtering maintains bacteria levels in the lag phase and leads to the dramatic extension of the brain slice lifespan. Brain slice viability was validated through electrophysiological recordings as well as live/dead cell assays. This system benefits researchers by monitoring incubation conditions and standardizing this artificial environment. It further provides viable tissue for two experimental days, reducing the time spent preparing brain slices and the number of animals required for research. PMID:24930889

  1. Coordinate singularities in harmonically sliced cosmologies

    NASA Astrophysics Data System (ADS)

    Hern, Simon D.

    2000-08-01

    Harmonic slicing has in recent years become a standard way of prescribing the lapse function in numerical simulations of general relativity. However, as was first noticed by Alcubierre [Phys. Rev. D 55, 5981 (1997)], numerical solutions generated using this slicing condition can show pathological behavior. In this paper, analytic and numerical methods are used to examine harmonic slicings of Kasner and Gowdy cosmological spacetimes. It is shown that in general the slicings are prevented from covering the whole of the spacetimes by the appearance of coordinate singularities. As well as limiting the maximum running times of numerical simulations, the coordinate singularities can lead to features being produced in numerically evolved solutions which must be distinguished from genuine physical effects.

  2. Photosynthesis and Respiration in Leaf Slices.

    ERIC Educational Resources Information Center

    Brown, Simon

    1998-01-01

    Demonstrates how leaf slices provide an inexpensive material for illustrating several fundamental points about the biochemistry of photosynthesis and respiration. Presents experiments that illustrate the effects of photon flux density and herbicides and carbon dioxide concentration. (DDR)

  3. Optical Sectioning and High Resolution in Single-Slice Structured Illumination Microscopy by Thick Slice Blind-SIM Reconstruction

    PubMed Central

    Jost, Aurélie; Tolstik, Elen; Feldmann, Polina; Wicker, Kai; Sentenac, Anne; Heintzmann, Rainer

    2015-01-01

    The microscope image of a thick fluorescent sample taken at a given focal plane is plagued by out-of-focus fluorescence and diffraction limited resolution. In this work, we show that a single slice of Structured Illumination Microscopy (two or three beam SIM) data can be processed to provide an image exhibiting tight sectioning and high transverse resolution. Our reconstruction algorithm is adapted from the blind-SIM technique which requires very little knowledge of the illumination patterns. It is thus able to deal with illumination distortions induced by the sample or illumination optics. We named this new algorithm thick slice blind-SIM because it models a three-dimensional sample even though only a single two-dimensional plane of focus was measured. PMID:26147644

  4. Review of scratch test studies of abrasion mechanisms

    SciTech Connect

    Kosel, T.H.

    1986-01-01

    The use of scratch tests to simulate the material removal mechanisms which occur during abrasion is reviewed. Although useful studies of the effect of the rake angle on material removal have been carried out using diamond tools, closer simulation of the mechanisms of material removal can be obtained using actual irregular individual abrasive particles as scratch tools. Previous studies are reviewed in which scratch tests have been performed with both conventional scratch test instruments and a specially designed system used for )ital in situ) scratch tests in the scanning electron microscope (SEM). Multiple-pass scratch tests over the same scratch path have been shown to create surface features and wear debris particles which are very similar to those produced by low-stress abrasion. Alumina (Al/sub 2/O/sub 3/) particles have been shown to produce continuous micromachining chips from the hard, brittle carbide phase of Stellite alloys, establishing direct cutting as the important mechanism of material removal for this type of abrasive. An )ital in situ) study of material removal from white cast irons by quartz particles has provided conclusive evidence that carbide removal does not occur by direct cutting but rather always involves microfracture. Previously unpublished work which has compared scratch tests with crushed quartz and alumina particles is included. Also described is a new scratch test system which controls the depth of cut rather than the scratch load in order to simulate high-stress abrasion, in which abrasive particles are constrained to a fixed depth of cut. Preliminary new results show substantially different carbide fracture behavior under fixed-depth conditions. 8 figs., 20 refs.

  5. Aeolian Abrasion, a Dominant Erosion Agent in the Martian Environment

    NASA Astrophysics Data System (ADS)

    Bridges, N.; Cooper, G.; Eddlemon, E.; Greeley, R.; Laity, J.; Phoreman, J.; Razdan, A.; van Note, S.; White, B.; Wilson, G.

    2004-12-01

    Aeolian abrasion is one of the predominant erosion mechanisms on Mars today. Martian ventifacts record the climate under which the rocks were modified (wind direction, wind speeds and particle flux) and therefore tie into the overall climatic regime of the planet. By better understanding the rates at which rocks abrade and the features diagnostic of specific climatic conditions, we can gain insight into past climates. Herein we report on numerical models, wind tunnel experiments, and field work to determine 1) Particle and kinetic fluxes on Earth and Mars, 2) the degree to which these parameters control abrasion, and 3) how, in detail, rocks of various shapes and compositions erode over time. Kinetic energy generally increases with height, whereas flux decreases, and impact angles, which affect energy transfer, and rebound effects are functions of the rock facet angle. This results in a non-linear relationship between abrasion potential and height that is a function of wind speed, planetary environment, and target geometry. We have computed the first three of these parameters numerically using a numerical saltation code, combined with published flux calculations These results have been compared to wind tunnel tests of flux vs. height, abrasion of erodible targets, and high speed video analysis under terrestrial and Martian pressures. We are also using high resolution laser scanning to characterize textures, shapes, and weathering changes for terrestrial and Martian rocks at the 100s of microns scale. We find that facet angle, texture, and rock heterogeneity are of critical importance in determining the rate and style of abrasion. Field and theoretical results demonstrate that high speed winds, not the integrated flux of lower speeds, and sand, not dust, produce most rock abrasion. On Mars, this requires sustained winds above 20-25 m/s at the near surface, a challenge in the current environment.

  6. Dental abrasion pattern in a selected group of Malaysians.

    PubMed

    Yaacob, H B; Park, A W

    1990-09-01

    Among 350 inhabitants of two villages, 31 (8.9%) cleaned their teeth using table salt and charcoal applied to their forefinger or a Melastoma brush. As a result, all had distinct forms of abrasion cavity on the labial surfaces of their teeth. All of the above three agents are highly abrasive and injurious to both the hard and soft oral tissues. This dying practice is only popular among a very small number of persons in the older age group, and should be discouraged. PMID:2230960

  7. Standardization of a Volumetric Displacement Measurement for Two-Body Abrasion Scratch Test Data Analysis

    NASA Technical Reports Server (NTRS)

    Street, K. W. Jr.; Kobrick, R. L.; Klaus, D. M.

    2011-01-01

    A limitation has been identified in the existing test standards used for making controlled, two-body abrasion scratch measurements based solely on the width of the resultant score on the surface of the material. A new, more robust method is proposed for analyzing a surface scratch that takes into account the full three-dimensional profile of the displaced material. To accomplish this, a set of four volume- displacement metrics was systematically defined by normalizing the overall surface profile to denote statistically the area of relevance, termed the Zone of Interaction. From this baseline, depth of the trough and height of the plowed material are factored into the overall deformation assessment. Proof-of-concept data were collected and analyzed to demonstrate the performance of this proposed methodology. This technique takes advantage of advanced imaging capabilities that allow resolution of the scratched surface to be quantified in greater detail than was previously achievable. When reviewing existing data analysis techniques for conducting two-body abrasive scratch tests, it was found that the ASTM International Standard G 171 specified a generic metric based only on visually determined scratch width as a way to compare abraded materials. A limitation to this method was identified in that the scratch width is based on optical surface measurements, manually defined by approximating the boundaries, but does not consider the three-dimensional volume of material that was displaced. With large, potentially irregular deformations occurring on softer materials, it becomes unclear where to systematically determine the scratch width. Specifically, surface scratches on different samples may look the same from a top view, resulting in an identical scratch width measurement, but may vary in actual penetration depth and/or plowing deformation. Therefore, two different scratch profiles would be measured as having identical abrasion properties, although they differ

  8. An Automated Approach for Slicing Plane Placement in Visual Data Analysis.

    PubMed

    Obermaier, Harald; Joy, Kenneth I

    2015-12-01

    Effective display and visual analysis of complex 3D data is a challenging task. Occlusions, overlaps, and projective distortions-as frequently caused by typical 3D rendering techniques-can be major obstacles to unambiguous and robust data analysis. Slicing planes are a ubiquitous tool to resolve several of these issues. They act as simple clipping geometry to provide clear cut-away views of the data. We propose to enhance the visualization and analysis process by providing methods for automatic placement of such slicing planes based on local optimization of gradient vector flow. The final obtained slicing planes maximize the total amount of information displayed with respect to a pre-specified importance function. We demonstrate how such automated slicing plane placement is able to support and enrich 3D data visualization and analysis in multiple scenarios, such as volume or surface rendering, and evaluate its performance in several benchmark data sets. PMID:26529461

  9. Organotypic Slice Cultures to Study Oligodendrocyte Dynamics and Myelination

    PubMed Central

    Hill, Robert A.; Medved, Jelena; Patel, Kiran D.; Nishiyama, Akiko

    2014-01-01

    NG2 expressing cells (polydendrocytes, oligodendrocyte precursor cells) are the fourth major glial cell population in the central nervous system. During embryonic and postnatal development they actively proliferate and generate myelinating oligodendrocytes. These cells have commonly been studied in primary dissociated cultures, neuron cocultures, and in fixed tissue. Using newly available transgenic mouse lines slice culture systems can be used to investigate proliferation and differentiation of oligodendrocyte lineage cells in both gray and white matter regions of the forebrain and cerebellum. Slice cultures are prepared from early postnatal mice and are kept in culture for up to 1 month. These slices can be imaged multiple times over the culture period to investigate cellular behavior and interactions. This method allows visualization of NG2 cell division and the steps leading to oligodendrocyte differentiation while enabling detailed analysis of region-dependent NG2 cell and oligodendrocyte functional heterogeneity. This is a powerful technique that can be used to investigate the intrinsic and extrinsic signals influencing these cells over time in a cellular environment that closely resembles that found in vivo. PMID:25177825

  10. In vitro effect of air-abrasion operating parameters on dynamic cutting characteristics of alumina and bio-active glass powders.

    PubMed

    Milly, H; Austin, R S; Thompson, I; Banerjee, A

    2014-01-01

    Minimally invasive dentistry advocates the maintenance of all repairable tooth structures during operative caries management in combination with remineralization strategies. This study evaluated the effect of air-abrasion operating parameters on its cutting efficiency/pattern using bio-active glass (BAG) powder and alumina powder as a control in order to develop its use as a minimally invasive operative technique. The cutting efficiency/pattern assessment on an enamel analogue, Macor, was preceded by studying the powder flow rate (PFR) of two different commercial intraoral air-abrasion units with differing powder-air admix systems. The parameters tested included air pressure, powder flow rate, nozzle-substrate distance, nozzle angle, shrouding the air stream with a curtain of water, and the chemistry of abrasive powder. The abraded troughs were scanned and analyzed using confocal white light profilometry and MountainsMap surface analysis software. Data were analyzed statistically using one-way and repeated-measures analysis of variance tests (p=0.05). The air-abrasion unit using a vibration mechanism to admix the abrasive powder with the air stream exhibited a constant PFR regardless of the set air pressure. Significant differences in cutting efficiency were observed according to the tested parameters (p<0.05). Alumina powder removed significantly more material than did BAG powder. Using low air pressure and suitable consideration of the effect of air-abrasion parameters on cutting efficiency/patterns can improve the ultraconservative cutting characteristics of BAG air-abrasion, thereby allowing an introduction of this technology for the controlled cleaning/removal of enamel, where it is indicated clinically. PMID:23718212

  11. Exposure to crystalline silica in abrasive blasting operations where silica and non-silica abrasives are used.

    PubMed

    Radnoff, Diane L; Kutz, Michelle K

    2014-01-01

    Exposure to respirable crystalline silica is a hazard common to many industries in Alberta but particularly so in abrasive blasting. Alberta occupational health and safety legislation requires the consideration of silica substitutes when conducting abrasive blasting, where reasonably practicable. In this study, exposure to crystalline silica during abrasive blasting was evaluated when both silica and non-silica products were used. The crystalline silica content of non-silica abrasives was also measured. The facilities evaluated were preparing metal products for the application of coatings, so the substrate should not have had a significant contribution to worker exposure to crystalline silica. The occupational sampling results indicate that two-thirds of the workers assessed were potentially over-exposed to respirable crystalline silica. About one-third of the measurements over the exposure limit were at the work sites using silica substitutes at the time of the assessment. The use of the silica substitute, by itself, did not appear to have a large effect on the mean airborne exposure levels. There are a number of factors that may contribute to over-exposures, including the isolation of the blasting area, housekeeping, and inappropriate use of respiratory protective equipment. However, the non-silica abrasives themselves also contain silica. Bulk analysis results for non-silica abrasives commercially available in Alberta indicate that many contain crystalline silica above the legislated disclosure limit of 0.1% weight of silica per weight of product (w/w) and this information may not be accurately disclosed on the material safety data sheet for the product. The employer may still have to evaluate the potential for exposure to crystalline silica at their work site, even when silica substitutes are used. Limited tests on recycled non-silica abrasive indicated that the silica content had increased. Further study is required to evaluate the impact of product recycling

  12. Whole-cell Patch-clamp Recordings in Brain Slices.

    PubMed

    Segev, Amir; Garcia-Oscos, Francisco; Kourrich, Saïd

    2016-01-01

    Whole-cell patch-clamp recording is an electrophysiological technique that allows the study of the electrical properties of a substantial part of the neuron. In this configuration, the micropipette is in tight contact with the cell membrane, which prevents current leakage and thereby provides more accurate ionic current measurements than the previously used intracellular sharp electrode recording method. Classically, whole-cell recording can be performed on neurons in various types of preparations, including cell culture models, dissociated neurons, neurons in brain slices, and in intact anesthetized or awake animals. In summary, this technique has immensely contributed to the understanding of passive and active biophysical properties of excitable cells. A major advantage of this technique is that it provides information on how specific manipulations (e.g., pharmacological, experimenter-induced plasticity) may alter specific neuronal functions or channels in real-time. Additionally, significant opening of the plasma membrane allows the internal pipette solution to freely diffuse into the cytoplasm, providing means for introducing drugs, e.g., agonists or antagonists of specific intracellular proteins, and manipulating these targets without altering their functions in neighboring cells. This article will focus on whole-cell recording performed on neurons in brain slices, a preparation that has the advantage of recording neurons in relatively well preserved brain circuits, i.e., in a physiologically relevant context. In particular, when combined with appropriate pharmacology, this technique is a powerful tool allowing identification of specific neuroadaptations that occurred following any type of experiences, such as learning, exposure to drugs of abuse, and stress. In summary, whole-cell patch-clamp recordings in brain slices provide means to measure in ex vivo preparation long-lasting changes in neuronal functions that have developed in intact awake animals

  13. Abrasion cross sections for Ne-20 projectiles at 2.1 GeV/nucleon

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.

    1983-01-01

    Utilizing eikonal scattering theory, an optical model potential approximation to the exact nucleus-nucleus multiple scattering series is used in an abrasion-ablation collision formalism to predict abrasion cross sections for relativistic Ne-20 projectile nuclei. Excellent agreement with recent experimental abrasion results is obtained. The sensitivity of the abrasion predictions to Pauli exclusion principle correlation effects and to the assumed shape of the nuclear single-particle density distribution is also demonstrated.

  14. Thin layer drying of tomato slices.

    PubMed

    Das Purkayastha, Manashi; Nath, Amit; Deka, Bidyut Chandra; Mahanta, Charu Lata

    2013-08-01

    The hot air convective drying characteristics of blanched tomato (Lycopersicon esculantum L.) slices have been investigated. Drying experiments were carried out at four different temperatures (50, 60, 65 and 70 °C). The effect of drying temperatures on the drying behavior of the tomato slices was evaluated. All drying experiments had only falling rate period. The average effective diffusivity values varied from 0.5453 × 10(-9) to 2.3871 × 10(-9) m(2)/s over the temperature range studied and the activation energy was estimated to be 61.004 kJ/mol. In order to select a suitable form of the drying curve, six different thin layer drying models (Henderson-Pabis, Page, Diamante et al., Wang and Singh, Logarithmic and Newton models) were fitted to the experimental data. The goodness of fit tests indicated that the Logarithmic model gave the best fit to experimental results, which was closely followed by the Henderson-Pabis model. The influence of varied drying temperatures on quality attributes of the tomato slices viz. Hunter color parameters, ascorbic acid, lycopene, titratable acidity, total sugars, reducing sugars and sugar/acid ratio of dried slices was also studied. Slices dried at 50 and 60 °C had high amount of total sugars, lycopene, sugar/acid ratio, Hunter L- and a-values. Drying of slices at 50 °C revealed optimum retention of ascorbic acid, sugar/acid ratio and red hue, whereas, drying at higher temperature (65 and 70 °C) resulted in a considerable decrease in nutrients and colour quality of the slices. PMID:24425966

  15. Development of a thermal reclamation system for spent blasting abrasive

    SciTech Connect

    Bryan, B.B.; Mensinger, M.C.; Rehmat, A.G.

    1991-01-01

    Abrasive blasting is the most economical method for paint removal from large surface areas such as the hulls and tanks of oceangoing vessels. Tens of thousands of tons of spent abrasive are generated annually by blasting operations in private and US Navy shipyards. Some of this material is classified as hazardous waste, and nearly all of it is currently being either stockpiled or disposed in landfills. The rapid decline in available landfill space and corresponding rise in landfill tipping fees pose a severe problem for shipyard operators throughout the US. This paper discusses the results of a research and development program initiated by the Institute of Gas Technology and supported by the US Navy to develop and test a fluidized-bed thermal reclamation system for spent abrasive waste minimization. Bench- and pilot-scale reclaimer tests and reclaimed abrasive performance tests are described along with the current status of a program to build and test a 5-ton/hour prototype reclaimer at a US Navy shipyard.

  16. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... wheel in motion. (5) Excluded machinery. Natural sandstone wheels and metal, wooden, cloth, or paper... apply to natural sandstone wheels or metal, wooden, cloth, or paper discs, having a layer of abrasive on... and Type 27A cutting-off wheels. (g) Certain internal wheels. (h) Type 4 tapered wheels. (i)...

  17. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... wheel in motion. (5) Excluded machinery. Natural sandstone wheels and metal, wooden, cloth, or paper... apply to natural sandstone wheels or metal, wooden, cloth, or paper discs, having a layer of abrasive on... and Type 27A cutting-off wheels. (g) Certain internal wheels. (h) Type 4 tapered wheels. (i)...

  18. 29 CFR 1926.303 - Abrasive wheels and tools.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... spindle speed at safe levels under all conditions of normal operation. (b) Guarding. (1) Grinding machines.... (1) Floor stand and bench mounted abrasive wheels, used for external grinding, shall be provided with safety guards (protection hoods). The maximum angular exposure of the grinding wheel periphery and...

  19. A nonmineralized approach to abrasion-resistant biomaterials

    PubMed Central

    Pontin, Michael G.; Moses, Dana N.; Waite, J. Herbert; Zok, Frank W.

    2007-01-01

    The tooth-like mouthparts of some animals consist of biomacromolecular scaffolds with few mineral components, making them intriguing paradigms of biostructural materials. In this study, the abrasion resistance of the jaws of one such animal, the bloodworm Glycera dibranchiata, has been evaluated by nanoindentation, nanoscratching, and wear testing. The hardest, stiffest, and most abrasion-resistant materials are found within a thin (<3 μm) surface layer near the jaw tip and a thicker (10–20 μm) subsurface layer, both rich in unmineralized Cu. These results are consistent with the supposition that Cu ions are involved in the formation of intermolecular coordination complexes between proteins, creating a highly cross-linked molecular network. The intervening layer contains aligned atacamite [Cu2(OH)3Cl] fibers and exhibits hardness and stiffness (transverse to the alignment direction) that are only slightly higher than those of the bulk material but lower than those of the two Cu-rich layers. Furthermore, the atacamite-containing layer is the least abrasion-resistant, by a factor of ≈3, even relative to the bulk material. These observations are broadly consistent with the behavior of engineering polymer composites with hard fiber or particulate reinforcements. The alignment of fibers parallel to the jaw surface, and the fiber proximity to the surface, are both suggestive of a natural adaptation to enhance bending stiffness and strength rather than to endow the surface regions with enhanced abrasion resistance. PMID:17702868

  20. Surface carbonization of titanium for abrasion-resistant implant materials.

    PubMed

    Zhu, Yuhe; Watari, Fumio

    2007-03-01

    Carbide layer was formed on the surface of Ti by heating in hydrocarbon atmosphere (benzene C6H6) at 1000-1400 degrees C using a high frequency induction heating method. Physical and mechanical properties of carbide-coated Ti were investigated to examine its potential as an abrasion-resistant implant material. Scanning electron microscopy (SEM) showed that the surface of Ti was covered with fine grains of 1-4 microm diameter, depending on heating conditions. In addition, carbide layer of about 1-25 microm thickness was observed on the cross-section of specimens by SEM and energy dispersive spectroscopy. Vickers hardness of surface carbide was found to be more than 2000. Further, Martens scratch test and ultrasonic scaler abrasion test showed that the indentation depth and width of carbide-coated Ti were much smaller than pure Ti, thereby confirming its high abrasion resistance. These results showed that for Ti implant materials that require high abrasion resistance, such as the abutment for dental implants, surface carbide coatings would be an effective means to improve their wear properties. PMID:17621941

  1. Potential of Air-Propelled Abrasives for Selective Weed Control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Novel forms of selective weed control are needed by many types of growers, but especially organic growers who are restricted from using synthetic herbicides. Abrasive grit made from corn cobs was expelled from a sand blaster at 517 kPa pressure and aimed at seedlings of common lambsquarters and corn...

  2. Abrasive blasting agents: designing studies to evaluate relative risk.

    PubMed

    Hubbs, Ann; Greskevitch, Mark; Kuempel, Eileen; Suarez, Fernando; Toraason, Mark

    Workers exposed to respirable crystalline silica used in abrasive blasting are at increased risk of developing a debilitating and often fatal fibrotic lung disease called silicosis. The National Institute for Occupational Safety and Health (NIOSH) recommends that silica sand be prohibited as abrasive blasting material and that less hazardous materials be used in blasting operations. However, data are needed on the relative risks associated with exposure to abrasive blasting materials other than silica. NIOSH has completed acute studies in rats (Hubbs et al., 2001; Porter et al., 2002). To provide dose-response data applicable to making recommendation for occupational exposure limits, NIOSH has collaborated with the National Toxicology Program (NTP) to design longer term studies with silica substitutes. For risk assessment purposes, selected doses will include concentrations that are relevant to human exposures. Rat lung burdens achieved should be comparable to those estimated in humans with working lifetime exposures, even if this results in "overloading" doses in rats. To quantify both dose and response, retained particle burdens in the lungs and lung-associated lymph nodes will be measured, as well as biochemical and pathological indices of pulmonary response. This design will facilitate assessment of the pulmonary fibrogenic potential of inhaled abrasive blasting agents at occupationally relevant concentrations. PMID:16020188

  3. Glycine metabolism in rat kidney cortex slices.

    PubMed

    Rowsell, E V; Al-Naama, M M; Rowsell, K V

    1982-04-15

    When rat kidney cortex slices were incubated with glycine or [1-14C]glycine, after correcting for metabolite changes with control slices, product formation and glycine utilization fitted the requirements of the equation: 2 Glycine leads to ammonia + CO2 + serine. Evidence is presented that degradation via glyoxylate, by oxidation or transamination, is unlikely to have any significant role in kidney glycine catabolism. It is concluded that glycine metabolism in rat kidney is largely via glycine cleavage closely coupled with serine formation. 1-C decarboxylation and urea formation with glycine in rat hepatocyte suspensions were somewhat greater than decarboxylation or ammonia formation in kidney slices, showing that in the rat, potentially, the liver is quantitatively the more important organ in glycine catabolism. There was no evidence of ammonia formation from glycine with rat brain cortex, heart, spleen or diaphragm and 1-C decarboxylation was very weak. PMID:6810880

  4. Development of Abrasion-Resistant Coating for Solar Reflective Films. Cooperative Research and Development Final Report, CRADA Number CRD-07-247

    SciTech Connect

    Gray, Matthew

    2015-10-01

    The purpose of this CRADA is to develop an abrasion-resistant coating, suitable for use on polymeric-based reflective films (e.g., the ReflecTech reflective film), that allows for improved scratch resistance and enables the use of aggressive cleaning techniques (e.g., direct contact methods like brushing) without damaging the specular reflectance properties of the reflective film.

  5. Tectonic slicing of subducting oceanic crust along plate interfaces: Numerical modeling

    NASA Astrophysics Data System (ADS)

    Ruh, J. B.; Le Pourhiet, L.; Agard, Ph.; Burov, E.; Gerya, T.

    2015-10-01

    Multikilometer-sized slivers of high-pressure low-temperature metamorphic oceanic crust and mantle are observed in many mountain belts. These blueschist and eclogite units were detached from the descending plate during subduction. Large-scale thermo-mechanical numerical models based on finite difference marker-in-cell staggered grid technique are implemented to investigate slicing processes that lead to the detachment of oceanic slivers and their exhumation before the onset of the continental collision phase. In particular, we investigate the role of the serpentinized subcrustal slab mantle in the mechanisms of shallow and deep crustal slicing. Results show that spatially homogeneous serpentinization of the sub-Moho slab mantle leads to complete accretion of oceanic crust within the accretionary wedge. Spatially discontinuous serpentinization of the slab mantle in form of unconnected patches can lead to shallow slicing of the oceanic crust below the accretionary wedge and to its deep slicing at mantle depths depending on the patch length, slab angle, convergence velocity and continental geothermal gradient. P-T paths obtained in this study are compared to natural examples of shallow slicing of the Crescent Terrane below Vancouver Island and deeply sliced crust of the Lago Superiore and Saas-Zermatt units in the Western Alps.

  6. Solid Lubrication Fundamentals and Applications. Chapter 5; Abrasion: Plowing and Cutting

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2001-01-01

    Chapter 5 discusses abrasion, a common wear phenomenon of great economic importance. It has been estimated that 50% of the wear encountered in industry is due to abrasion. Also, it is the mechanism involved in the finishing of many surfaces. Experiments are described to help in understanding the complex abrasion process and in predicting friction and wear behavior in plowing and/or cutting. These experimental modelings and measurements used a single spherical pin (asperity) and a single wedge pin (asperity). Other two-body and three-body abrasion studies used hard abrasive particles.

  7. ID slicing and the automated factory

    NASA Technical Reports Server (NTRS)

    Lewandowski, T.

    1982-01-01

    The automation of the slicing system utilizing internal-diameter saws for the production of the silicon wafers used in solar arrays is discussed. It is argued that saw productivity can be increased by reducing silicon waste, decreasing usage of consumables, keeping the saw slicing, and increasing the cutting speed. Several machine enhancements utilizing automatic control are discussed. The need for record keeping to anticipate maintenance operations is noted, and a digital serial communication interface with the microprocessor-based saws is recommended. Distributed control of the manufacturing process is discussed in detail, and is recommended as a method for increasing productivity.

  8. Ultra-fast MRI of the human brain with simultaneous multi-slice imaging

    NASA Astrophysics Data System (ADS)

    Feinberg, David A.; Setsompop, Kawin

    2013-04-01

    The recent advancement of simultaneous multi-slice imaging using multiband excitation has dramatically reduced the scan time of the brain. The evolution of this parallel imaging technique began over a decade ago and through recent sequence improvements has reduced the acquisition time of multi-slice EPI by over ten fold. This technique has recently become extremely useful for (i) functional MRI studies improving the statistical definition of neuronal networks, and (ii) diffusion based fiber tractography to visualize structural connections in the human brain. Several applications and evaluations are underway which show promise for this family of fast imaging sequences.

  9. Abrasive Wear Study of NiCrFeSiB Flame Sprayed Coating

    NASA Astrophysics Data System (ADS)

    Sharma, Satpal

    2013-10-01

    In the present study, abrasive wear behavior of NiCrFeSiB alloy coating on carbon steel was investigated. The NiCrFeSiB coating powder was deposited by flame spraying process. The microstructure, porosity and hardness of the coatings were evaluated. Elemental mapping was carried out in order to study the distribution of various elements in the coating. The abrasive wear behavior of these coatings was investigated under three normal loads (5, 10 and 15 N) and two abrasive grit sizes (120 and 320 grit). The abrasive wear rate was found to increase with the increase of load and abrasive size. The abrasive wear resistance of coating was found to be 2-3 times as compared to the substrate. Analysis of the scanning electron microscope images revealed cutting and plowing as the material removal mechanisms in these coatings under abrasive wear conditions used in this investigation.

  10. Adhesion and wear behaviour of NCD coatings on Si3N4 by micro-abrasion tests.

    PubMed

    Silva, F G; Neto, M A; Fernandes, A J S; Costa, F M; Oliveira, F J; Silva, R F

    2009-06-01

    Nanocrystalline diamond (NCD) coatings offer an excellent alternative for tribological applications, preserving most of the intrinsic mechanical properties of polycrystalline CVD diamond and adding to it an extreme surface smoothness. Silicon nitride (Si3N4) ceramics are reported to guarantee high adhesion levels to CVD microcrystalline diamond coatings, but the NCD adhesion to Si3N4 is not yet well established. Micro-abrasion tests are appropriate for evaluating the abrasive wear resistance of a given surface, but they also provide information on thin film/substrate interfacial resistance, i.e., film adhesion. In this study, a comparison is made between the behaviour of NCD films deposited by hot-filament chemical vapour deposition (HFCVD) and microwave plasma assisted chemical vapour deposition (MPCVD) techniques. Silicon nitride (Si3N4) ceramic discs were selected as substrates. The NCD depositions by HFCVD and MPCVD were carried out using H2-CH4 and H2-CH4-N2 gas mixtures, respectively. An adequate set of growth parameters was chosen for each CVD technique, resulting in NCD films having a final thickness of 5 microm. A micro-abrasion tribometer was used, with 3 microm diamond grit as the abrasive slurry element. Experiments were carried out at a constant rotational speed (80 r.p.m.) and by varying the applied load in the range of 0.25-0.75 N. The wear rate for MPCVD NCD (3.7 +/- 0.8 x 10(-5) mm3 N(-1) m(-1)) is compatible with those reported for microcrystalline CVD diamond. The HFCVD films displayed poorer adhesion to the Si3N4 ceramic substrates than the MPCVD ones. However, the HFCVD films show better wear resistance as a result of their higher crystallinity according to the UV Raman data, despite evidencing premature adhesion failure. PMID:19504945

  11. Sliding and abrasive wear resistance of thermal-sprayed WC-CO coatings

    NASA Astrophysics Data System (ADS)

    Qiao, Yunfei; Liu, Yourong; Fischer, Traugott E.

    2001-03-01

    We studied the resistance of the coatings to abrasive and unlubricated sliding wear of 40 WC/Co coatings applied by high velocity oxygen fuel (HVOF), high-energy plasma spray (HEPS), and high velocity plasma spray (HVPS), using commercial and nanostructured experimental powders. The hardness of the coatings varies from 3 to 13 GPA, which is much lower than that of sintered samples (10 to 23 GPA) because of the porosity of the coatings. Phase analysis by x-ray diffraction revealed various amounts of decarburization in the coatings, some of which contain WC, W2C, W, and η phase. The abrasive and sliding wear resistance is limited by the hardness of the samples. For a given hardness, the wear resistance is lowered by decarburization, which produces a hard but brittle phase. Nanocarb powders have the shape of thin-walled hollow spheres that heat up rapidly in the gun and are more prone to decarburization than commercial materials. The work shows that, in order to obtain the performance of nanostructured coatings, the powder and spray techniques must be modified.

  12. Standardization of a Volumetric Displacement Measurement for Two-Body Abrasion Scratch Test Data Analysis

    NASA Technical Reports Server (NTRS)

    Kobrick, Ryan L.; Klaus, David M.; Street, Kenneth W., Jr.

    2010-01-01

    A limitation has been identified in the existing test standards used for making controlled, two-body abrasion scratch measurements based solely on the width of the resultant score on the surface of the material. A new, more robust method is proposed for analyzing a surface scratch that takes into account the full three-dimensional profile of the displaced material. To accomplish this, a set of four volume displacement metrics are systematically defined by normalizing the overall surface profile to statistically denote the area of relevance, termed the Zone of Interaction (ZOI). From this baseline, depth of the trough and height of the ploughed material are factored into the overall deformation assessment. Proof of concept data were collected and analyzed to demonstrate the performance of this proposed methodology. This technique takes advantage of advanced imaging capabilities that now allow resolution of the scratched surface to be quantified in greater detail than was previously achievable. A quantified understanding of fundamental particle-material interaction is critical to anticipating how well components can withstand prolonged use in highly abrasive environments, specifically for our intended applications on the surface of the Moon and other planets or asteroids, as well as in similarly demanding, harsh terrestrial settings

  13. nem_slice ver. 3.34

    2009-06-08

    Nem_slice reads in a finite element model description of the geometry of a problem from an ExodusII file and generates either a nodal or elemental graph of the problem. It then calls Chaco to load balance the graph and then outputs a NemesisI load-balance file.

  14. [A simple vibratome for brain slice].

    PubMed

    Xia, J H; Xing, B R; Gu, Q; Hua, S Y

    1989-12-01

    A simple vibratome was fabricated using double-function electric shaver and microscopic platform. Spontaneous discharge of neurons in hippocampal and hypothalamic brain slices (in 300-400 microns thick) prepared by the vibratome could kept above 12 hours in artificial cerebro-spinal fluid. PMID:2697084

  15. Detecting Psychopathy from Thin Slices of Behavior

    ERIC Educational Resources Information Center

    Fowler, Katherine A.; Lilienfeld, Scott O.; Patrick, Christopher J.

    2009-01-01

    This study is the first to demonstrate that features of psychopathy can be reliably and validly detected by lay raters from "thin slices" (i.e., small samples) of behavior. Brief excerpts (5 s, 10 s, and 20 s) from interviews with 96 maximum-security inmates were presented in video or audio form or in both modalities combined. Forty raters used…

  16. Thin-Slice Perception Develops Slowly

    ERIC Educational Resources Information Center

    Balas, Benjamin; Kanwisher, Nancy; Saxe, Rebecca

    2012-01-01

    Body language and facial gesture provide sufficient visual information to support high-level social inferences from "thin slices" of behavior. Given short movies of nonverbal behavior, adults make reliable judgments in a large number of tasks. Here we find that the high precision of adults' nonverbal social perception depends on the slow…

  17. Wheel Abrasion Experiment Metals Selection for Mars Pathfinder Mission

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Fatemi, Navid S.; Wilt, David M.; Ferguson, Dale C.; Hoffman, Richard; Hill, Maria M.; Kaloyeros, Alain E.

    1996-01-01

    A series of metals was examined for suitability for the Wheel Abrasion Experiment, one of ten microrover experiments of the Mars Pathfinder Mission. The seven candidate metals were: Ag, Al, Au, Cu, Ni, Pt, and W. Thin films of candidate metals from 0.1 to 1.0 micrometer thick were deposited on black anodized aluminum coupons by e-beam and resistive evaporation and chemical vapor deposition. Optical, corrosion, abrasion, and adhesion criteria were used to select Al, Ni, and Pt. A description is given of the deposition and testing of thin films, followed by a presentation of experimental data and a brief discussion of follow-on testing and flight qualification.

  18. Abrasion Testing of Critical Components of Hydrokinetic Devices

    SciTech Connect

    Worthington, Monty; Ali, Muhammad; Ravens, Tom

    2013-12-06

    The objective of the Abrasion Testing of Critical Components of Hydrokinetic Devices (Project) was to test critical components of hydrokinetic devices in waters with high levels of suspended sediment – information that is widely applicable to the hydrokinetic industry. Tidal and river sites in Alaska typically have high suspended sediment concentrations. High suspended sediment also occurs in major rivers and estuaries throughout the world and throughout high latitude locations where glacial inputs introduce silt into water bodies. In assessing the vulnerability of technology components to sediment induced abrasion, one of the greatest concerns is the impact that the sediment may have on device components such as bearings and seals, failures of which could lead to both efficiency loss and catastrophic system failures.

  19. Microstructure and abrasive wear in silicon nitride ceramics

    SciTech Connect

    Dogan, Cynthia P.; Hawk, Jeffrey A.

    2001-10-01

    It is well known that abrasive wear resistance is not strictly a materials property, but also depends upon the specific conditions of the wear environment. Nonetheless, characteristics of the ceramic microstructure do influence its hardness and fracture toughness and must, therefore, play an active role in determining howa ceramic will respond to the specific stress states imposed upon it by the wear environment. In this study, the ways in which composition and microstructure influence the abrasive wear behavior of six commercially-produced silicon nitride based ceramics are examined. Results indicate that microstructural parameters, such as matrix grain size and orientation, porosity, and grain boundary microstructure, and thermal expansion mismatch stresses created as the result of second phase formation, influence the wear rate through their effect on wear sheet formation and subsurface fracture. It is also noted that the potential impact of these variables on the wear rate may not be reflected in conventional fracture toughness measurements.

  20. A physically-based abrasive wear model for composite materials

    SciTech Connect

    Lee, Gun Y.; Dharan, C.K.H.; Ritchie, Robert O.

    2001-05-01

    A simple physically-based model for the abrasive wear of composite materials is presented based on the mechanics and mechanisms associated with sliding wear in soft (ductile) matrix composites containing hard (brittle) reinforcement particles. The model is based on the assumption that any portion of the reinforcement that is removed as wear debris cannot contribute to the wear resistance of the matrix material. The size of this non-contributing portion of the reinforcement is estimated by modeling the three primary wear mechanisms, specifically plowing, interfacial cracking and particle removal. Critical variables describing the role of the reinforcement, such as its relative size and the nature of the matrix/reinforcement interface, are characterized by a single contribution coefficient, C. Predictions are compared with the results of experimental two-body (pin-on drum) abrasive wear tests performed on a model aluminum particulate-reinforced epoxy matrix composite material.

  1. Self inflicted corneal abrasions due to delusional parasitosis

    PubMed Central

    Meraj, Adeel; Din, Amad U; Larsen, Lynn; Liskow, Barry I

    2011-01-01

    The authors report a case of self inflicted bilateral corneal abrasions and skin damage due to ophthalmic and cutaneous delusional parasitosis. A male in his 50s presented with a 10 year history of believing that parasites were colonizing his skin and biting into his skin and eyes. The patient had received extensive medical evaluations that found no evidence that symptoms were due to a medical cause. He was persistent in his belief and had induced bilateral corneal abrasions and skin damage by using heat lamps and hair dryers in an attempt to disinfect his body. The patient was treated with olanzapine along with treatment for his skin and eyes. His delusional belief system persisted but no further damage to his eyes and skin was noted on initial follow-up. PMID:22689836

  2. Wear and abrasion resistance selection maps of biological materials.

    PubMed

    Amini, Shahrouz; Miserez, Ali

    2013-08-01

    The mechanical design of biological materials has generated widespread interest in recent years, providing many insights into their intriguing structure-property relationships. A critical characteristic of load-bearing materials, which is central to the survival of many species, is their wear and abrasion tolerance. In order to be fully functional, protective armors, dentitious structures and dynamic appendages must be able to tolerate repetitive contact loads without significant loss of materials or internal damage. However, very little is known about this tribological performance. Using a contact mechanics framework, we have constructed materials selection charts that provide general predictions about the wear performance of biological materials as a function of their fundamental mechanical properties. One key assumption in constructing these selection charts is that abrasion tolerance is governed by the first irreversible damage at the contact point. The maps were generated using comprehensive data from the literature and encompass a wide range of materials, from heavily mineralized to fully organic materials. Our analysis shows that the tolerance of biological materials against abrasion depends on contact geometry, which is ultimately correlated to environmental and selective pressures. Comparisons with experimental data from nanoindentation experiments are also drawn in order to verify our predictions. With the increasing amount of data available for biological materials also comes the challenge of selecting relevant model systems for bioinspired materials engineering. We suggest that these maps will be able to guide this selection by providing an overview of biological materials that are predicted to exhibit the best abrasion tolerance, which is of fundamental interest for a wide range of applications, for instance in restorative implants and protective devices. PMID:23643608

  3. Raising the resistance of mainline pump parts to hydraulic abrasion

    SciTech Connect

    Belousov, V.Ya.; Borisenko, V.V.; Zhuravlev, Yu.V.

    1988-01-01

    The authors investigate the diffusion coating of mainline petroleum pump surfaces with boron carbides and the subsequent hardness and abrasion resistance of the working surfaces based on the temperature of the treatment and the depth and concentration of the coating. Industrial testing on an NM 2500 x 230 centrifugal pump demonstrated an increase in service life by a factor of 2 to 2.5. The process has been put into production at an annual savings per pump of 4000 rubles.

  4. Abrasion of Candidate Spacesuit Fabrics by Simulated Lunar Dust

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Meador, Mary Ann; Rogers, Kerry J.; Sheehy, Brennan H.

    2009-01-01

    A protocol has been developed that produced the type of lunar soil abrasion damage observed on Apollo spacesuits. This protocol was then applied to four materials (Kevlar(Registered TradeMark), Vectran(Registered TradeMark), Orthofabric, and Tyvek(Registered TradeMark)) that are candidates for advanced spacesuits. Three of the four new candidate fabrics (all but Vectran(Registered TradeMark)) were effective at keeping the dust from penetrating to layers beneath. In the cases of Kevlar(Registered TradeMark) and Orthofabric this was accomplished by the addition of a silicone layer. In the case of Tyvek , the paper structure was dense enough to block dust transport. The least abrasive damage was suffered by the Tyvek(Registered TradeMark). This was thought to be due in large part to its non-woven paper structure. The woven structures were all abraded where the top of the weave was struck by the abrasive. Of these, the Orthofabric suffered the least wear, with both Vectran(Registered TradeMark) and Kevlar(Registered TradeMark) suffering considerably more extensive filament breakage.

  5. Abrasion of eroded root dentine brushed with different toothpastes.

    PubMed

    De Menezes, Márcio; Turssi, Cecilia Pedroso; Hara, Anderson Takeo; Messias, Danielle Cristine Furtado; Serra, Mônica Campos

    2004-09-01

    This study evaluated the surface roughness change and wear provided by different dentifrices on root dentine previously exposed to erosive challenges. According to a randomized complete block design, 150 slabs of bovine root dentine (6 x 3 x 2 mm) were ground flat and polished. In an area of 4 x 3 mm on the dentine surface, specimens were submitted to five erosive/abrasive events, each one composed by: exposure to Sprite Diet or distilled water for 5 min, then to a remineralizing solution for 1 min, and simulation of 5,000 brushing strokes. Four dentifrices--regular (RE), baking soda (BS), whitening (WT) and tartar control (TC)--and distilled water (CO), used as control, were compared. Final texture and the wear depth were evaluated using a profilometer. ANOVA did not show significant interaction, indicating that the effect of dentifrices on both surface roughness change and wear did not depend on whether or not the dentine was eroded ( p>0.05). There was no difference between abrasion of eroded and sound dentine. The Tukey's test revealed that WT, BS and TC provided the highest increase in surface roughness differing from RE and CO. TC yielded the deepest wear of root dentine, whereas RE and CO, the shallowest. No significant difference in wear among BS, TC and WT were observed. Within the limitations of this study, the data showed that abrasion of both eroded and sound root dentine was dependent on the dentifrice used. PMID:15146320

  6. Shotcup petal abrasions in close range .410-caliber shotgun injuries.

    PubMed

    Dowling, G P; Dickinson, J A; Cooke, C T

    1988-01-01

    Shotcup petal abrasions centered around a shotgun wound of entrance are generally thought to occur at a range of 30 to 90 cm. A suicidal .410-caliber shotgun injury of the right eye is described in which typical petal abrasions were noted around the entrance wound. However, significant soot deposition around the wound suggested that the range of fire was less than 30 cm and perhaps closer to 15 cm. Test-firing of the weapon and ammunition used by the decedent showed some spread of the shotcup petals at a range of 7.5 cm, progressing to maximum spread at 30 to 52.5 cm. Further testing with other .410 ammunition, containing shotcups, confirmed the spread of shotcup petals at ranges less than 30 cm, irrespective of manufacturer, shotshell length, and birdshot size. When a variety of shotguns were tested, it was found that one weapon with a very short barrel and cylinder bore did not exhibit petal spread until a range of 30 cm was reached. The remaining shotguns, with longer barrels and full choke, all demonstrated definite petal spread at a range of 12.5 cm. The long, narrow configuration of .410 shotcup petals may explain their early spread and the production of petal abrasions at ranges of less than 30 cm. PMID:3351464

  7. The Characteristics of LTP Induced in Hippocampal Slices Are Dependent on Slice-Recovery Conditions

    ERIC Educational Resources Information Center

    Godaux, Emile; Ris, Laurence; Capron, Brigitte; Sindic, Christian

    2006-01-01

    In area CA1 of hippocampal slices which are allowed to recover from slicing "in interface" and where recordings are carried out in interface, a single 1-sec train of 100-Hz stimulation triggers a short-lasting long-term potentiation (S-LTP), which lasts 1-2 h, whereas multiple 1-sec trains induce a long-lasting LTP (L-LTP), which lasts several…

  8. TISSUE SLICES IN THE STUDY OF LUNG METABOLISM AND TOXICOLOGY

    EPA Science Inventory

    Lung tissue slices are model systems for the study of pulmonary metabolism. Because of the speed and simplicity of slice preparation, lung slices have been used in studies of oxygen, amino acid, carbohydrate and lipid utilization and adenine nucleotide metabolism. Dose-response c...

  9. Visible Human Slice Web Server: a first assessment

    NASA Astrophysics Data System (ADS)

    Hersch, Roger D.; Gennart, Benoit A.; Figueiredo, Oscar; Mazzariol, Marc; Tarraga, Joaquin; Vetsch, S.; Messerli, Vincent; Welz, R.; Bidaut, Luc M.

    1999-12-01

    The Visible Human Slice Server started offering its slicing services at the end of June 1998. From that date until the end of May, more than 280,000 slices were extracted from the Visible Man, by layman interested in anatomy, by students and by specialists. The Slice Server is based one Bi-Pentium PC and 16 disks. It is a scaled down version of a powerful parallel server comprising 5 Bi-Pentium Pro PCs and 60 disks. The parallel server program was created thanks to a computer-aided parallelization framework, which takes over the task of creating a multi-threaded pipelined parallel program from a high-level parallel program description. On the full blown architecture, the parallel program enables the extraction and resampling of up to 5 color slices per second. Extracting 5 slice/s requires to access the disks and extract subvolumes of the Visible Human at an aggregate throughput of 105 MB/s. The publicly accessible server enables to extract slices having any orientation. The slice position and orientation can either be specified for each slice separately or as a position and orientation offered by a Java applet and possible future improvements. In the very near future, the Web Slice Server will offer additional services, such as the possibility to extract ruled surfaces and to extract animations incorporating slices perpendicular to a user defined trajectory.

  10. The effect of hydrogen peroxide on polishing removal rate in CMP with various abrasives

    NASA Astrophysics Data System (ADS)

    Manivannan, R.; Ramanathan, S.

    2009-01-01

    The effect of hydrogen peroxide in chemical mechanical planarization slurries for shallow trench isolation was investigated. The various abrasives used in this study were ceria, silica, alumina, zirconia, titania, silicon carbide, and silicon nitride. Hydrogen peroxide suppresses the polishing of silicon dioxide and silicon nitride surfaces by ceria abrasives. The polishing performances of other abrasives were either unaffected or enhanced slightly with the addition of hydrogen peroxide. The ceria abrasives were treated with hydrogen peroxide, and the polishing of the work surfaces with the treated abrasive shows that the inhibiting action of hydrogen peroxide is reversible. It was found that the effect of hydrogen peroxide as an additive is a strong function of the nature of the abrasive particle.

  11. Trafficking of astrocytic vesicles in hippocampal slices

    SciTech Connect

    Potokar, Maja; Kreft, Marko; Celica Biomedical Center, Technology Park 24, 1000 Ljubljana ; Lee, So-Young; Takano, Hajime; Haydon, Philip G.; Zorec, Robert; Celica Biomedical Center, Technology Park 24, 1000 Ljubljana

    2009-12-25

    The increasingly appreciated role of astrocytes in neurophysiology dictates a thorough understanding of the mechanisms underlying the communication between astrocytes and neurons. In particular, the uptake and release of signaling substances into/from astrocytes is considered as crucial. The release of different gliotransmitters involves regulated exocytosis, consisting of the fusion between the vesicle and the plasma membranes. After fusion with the plasma membrane vesicles may be retrieved into the cytoplasm and may continue to recycle. To study the mobility implicated in the retrieval of secretory vesicles, these structures have been previously efficiently and specifically labeled in cultured astrocytes, by exposing live cells to primary and secondary antibodies. Since the vesicle labeling and the vesicle mobility properties may be an artifact of cell culture conditions, we here asked whether the retrieving exocytotic vesicles can be labeled in brain tissue slices and whether their mobility differs to that observed in cell cultures. We labeled astrocytic vesicles and recorded their mobility with two-photon microscopy in hippocampal slices from transgenic mice with fluorescently tagged astrocytes (GFP mice) and in wild-type mice with astrocytes labeled by Fluo4 fluorescence indicator. Glutamatergic vesicles and peptidergic granules were labeled by the anti-vesicular glutamate transporter 1 (vGlut1) and anti-atrial natriuretic peptide (ANP) antibodies, respectively. We report that the vesicle mobility parameters (velocity, maximal displacement and track length) recorded in astrocytes from tissue slices are similar to those reported previously in cultured astrocytes.

  12. A Profilometric Study to Assess the Role of Toothbrush and Toothpaste in Abrasion Process

    PubMed Central

    Kumar, Sandeep; Kumar Singh, Siddharth; Gupta, Anjali; Roy, Sayak; Sareen, Mohit; Khajuria, Sarang

    2015-01-01

    Statement of the Problem Despite of many studies conducted on toothbrushes and toothpaste to find out the culprit for abrasion, there is no clear cut evidence to pin point the real cause for abrasion. Purpose An in vitro assessment of the role of different types of toothbrushes (soft/ medium/hard) in abrasion process when used in conjunction with and without a dentifrice. Materials and Method Forty five freshly extracted, sound, human incisor teeth were collected for this study. Enamel specimens of approximately 9 mm2 were prepared by gross trimming of extracted teeth using a lathe machine (Baldor 340 Dental lathe; Ohio, USA). They were mounted on separate acrylic bases. The specimens were divided into three groups, each group containing 15 mounted specimens. Group 1 specimens were brushed with soft toothbrush; Group 2 brushed with medium toothbrush and Group 3 with hard toothbrush. Initially, all the mounted specimens in each group were brushed using dentifrice and then the same procedure was repeated with water as control. Profilometric readings were recorded pre and post to tooth brushing and the differences in readings served as proxy measure to assess surface abrasion. These values were then compared to each other. Kruskal Wallis and Mann-Whitney U test were performed. Results The results showed that brushing, with water alone, caused less abrasion than when toothpaste was added (p< 0.008). When brushed with water, the harder toothbrush caused more abrasion (higher Ra-value), but when toothpaste was added, the softer toothbrush caused more abrasion (p< 0.001). Conclusion Besides supporting the fact that toothpaste is needed to create a significant abrasion, this study also showed that a softer toothbrush can cause more abrasion than harder ones. The flexibility of bristles is only secondary to abrasion process and abrasivity of dentifrice has an important role in abrasion process. PMID:26535407

  13. [Composites versus amalgam: comparative measurements of abrasion resistance in vivo: 1-year results].

    PubMed

    Meier, C; Lutz, F

    1979-03-01

    A method for the in-vivo measurement of wear resistance of restorative materials is described. A profilometer is used to record the reduction in vertical dimension of the test material's occlusal surface. This loss of substance is calculated as the wear resistance index. The technique was used in a 13 month clinical evaluation of 3 different restorative materials, Adaptic, Amalgam (Dispersalloy) and Estic microfill. The procedure is simple in execution and very accurate. Statistical analysis has shown significant differences in wear resistance of the examined materials independent of patient variation. Attrition and abrasion were definitely greater with a standard composite material (Adaptic) than with amalgam and a test composite (Estic microfill). The newly developed composite material utilizing extremely fine filler particles of pyrogenic SiO2 (Estic microfill) was shown to be comparable to amalgam in wear resistance during the 13-month test period. PMID:293032

  14. A comparison of the abrasiveness of six ceramic surfaces and gold.

    PubMed

    Jacobi, R; Shillingburg, H T; Duncanson, M G

    1991-09-01

    A type III gold alloy and six different ceramic surfaces were secured in an abrasion machine opposing extracted teeth to determine their relative abrasiveness and resistance to wear. The rankings of restorative materials from least abrasive to most abrasive were: gold alloy, polished; cast ceramic, polished; porcelain, polished; cast ceramic, polished and shaded; porcelain, polished and glazed; cast ceramic, cerammed skin shaded; and cast ceramic, cerammed skin unshaded. The ranking of materials from most wear-resistant to least wear-resistant was: gold alloy, cast ceramic cerammed, cast ceramic cerammed and shaded, porcelain polished, porcelain glazed, cast ceramic polished and shaded, and cast ceramic polished. PMID:1800724

  15. A Review of Variable Slicing in Fused Deposition Modeling

    NASA Astrophysics Data System (ADS)

    Nadiyapara, Hitesh Hirjibhai; Pande, Sarang

    2016-06-01

    The paper presents a literature survey in the field of fused deposition of plastic wires especially in the field of slicing and deposition using extrusion of thermoplastic wires. Various researchers working in the field of computation of deposition path have used their algorithms for variable slicing. In the study, a flowchart has also been proposed for the slicing and deposition process. The algorithm already been developed by previous researcher will be used to be implemented on the fused deposition modelling machine. To demonstrate the capabilities of the fused deposition modeling machine a case study has been taken. It uses a manipulated G-code to be fed to the fused deposition modeling machine. Two types of slicing strategies, namely uniform slicing and variable slicing have been evaluated. In the uniform slicing, the slice thickness has been used for deposition is varying from 0.1 to 0.4 mm. In the variable slicing, thickness has been varied from 0.1 in the polar region to 0.4 in the equatorial region Time required and the number of slices required to deposit a hemisphere of 20 mm diameter have been compared with that using the variable slicing.

  16. A rotary-airlock valve resists abrasive mixtures

    SciTech Connect

    Not Available

    1993-03-01

    Hill and Griffith (H and G, Cincinnati, Ohio) is a leading supplier of custom-blended additives to founderies. Thousands of tons of clay and carbon blends such as bentonite, gilsonite and pulverized coal, pass through the company's rotary-airlock feeding system each month. H and G's original rotary valves had cylinders lined with chrome, and closed-end rotors with tips made from nickel-chromium alloys. These valves remained in service for a maximum of only three months each. During that time, the abrasive mixtures passing through the valves virtually eroded them, increasing tolerances and causing significant air leakage. The leaks caused the pneumatic line to plug up, reducing the velocity of the line below the minimum level needed to carry any material. To overcome the leakage, a second blower was added to the system. This unit supplied an additional 40 brake hp to the pneumatic-conveying line. With constant maintenance of the valve and the continuous operation of both blowers, H and G was able to extend the valve's life by nine months. After 20 years of trying valves with various configuration, H and G installed a Smoot Type 6 rotary-airlock valve in September of 1985. The new valve's internals were made from abrasion-resistant grades of NiHard and Stellite. This combination of alloys prolonged the active life of the valve by improving its abrasion resistance. During its first year, the Smoot valve did not break down, leak air or require use of the secondary blower. After its first year of service no wear was found on the valve's internal surfaces. Another mechanical analysis was performed in 1991, after five additional years of valve operation. The valve, which had now handled more than 250,000 tons of product, showed minimal wear. H and G's capital costs had been reduced from 25[cents]/ton to 3[cents]/ton by the new valve.

  17. Abrasion in pyroclastic density currents: Insights from tumbling experiments

    NASA Astrophysics Data System (ADS)

    Kueppers, Ulrich; Putz, Constanze; Spieler, Oliver; Dingwell, Donald B.

    2012-01-01

    During granular mass movements of any kind, particles may interact with one another. The degree of interaction is a function of several variables including; grain-size distribution, particle concentration, density stratification and degree of fluidisation. The impact of particle interaction is additionally influenced by the relative speed, impact angle and clast temperature. Thus, both source conditions and transport-related processes are expected to influence the flow dynamics of pyroclastic density currents and their subsequent deposition. Here, we use tumbling experiments to shed light on the susceptibility of porous clasts to abrasion. We investigated the abrasion of unaltered volcanic rocks (5.7-80 vol.% porosity) from Unzen (Japan), Bezymianny (Russia) and Santorini (Greece) volcanoes as well as one synthetic analogue material, an insulating material with the trade name Foamglas® (95 vol.% porosity). Each experiment started with angular fragments generated in a jaw crusher from larger clasts. Two experimental series were performed; on samples with narrow and broader grain-size distributions, respectively. The dry samples were subject to rotational movement at constant speed and ambient temperature in a gum rotational tumbler for durations of 15, 30, 45, 60 and 120 min. The amount of volcanic ash (particles <2 mm) generated was evaluated as a function of experimental duration and sample porosity. We term “abrasion” as the ash fraction generated during the experiments. The observed increase of “abrasion” with increasing sample porosity and experimental duration is initially non-linear but becomes linear for experiments of 30 min duration or longer. For any given sample, abrasion appears to be more effective for coarser samples and larger initial mass. The observed range of ash generated in our experiments is between 1 and 35 wt.%. We find that this amount generally increases with increasing initial clast size or increasing breadth of the initial grain

  18. Heat sealable, flame and abrasion resistant coated fabric

    NASA Technical Reports Server (NTRS)

    Tschirch, R. P.; Sidman, K. R. (Inventor)

    1983-01-01

    Flame retardant, abrasion resistant elastomeric compositions are disclosed which are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Heat sealable coated fabrics employing such elastomeric compositions as coating film are produced by dissolving the elastomeric composition to form a solution, casting the solution onto a release paper and drying it to form an elastomeric film. The film is then bonded to a woven, knitted, or felted fabric.

  19. Culturing thick brain slices: An interstitial 3D microperfusion system for enhanced viability

    PubMed Central

    Rambani, Komal; Vukasinovic, Jelena; Glezer, Ari; Potter, Steve M.

    2009-01-01

    Brain slice preparations are well-established models for a wide spectrum of in vitro investigations in the neuroscience discipline. However, these investigations are limited to acute preparations or thin organotypic culture preparations due to the lack of a successful method that allows culturing of thick organotypic brain slices. Thick brain slice cultures suffer necrosis due to ischemia deep in the tissue resulting from a destroyed circulatory system and subsequent diffusion-limited supply of nutrients and oxygen. Although thin organotypic brain slice cultures can be successfully cultured using a well established roller tube method (a monolayer organotypic culture) (Gahwiler B H, 1981) or a membrane insert method (up to 1–4 cell layers, <150μm)(Stoppini L et al., 1991), these methods fail to support thick tissue preparations. A few perfusion methods (using submerged or interface/microfluidic chambers) have been reported to enhance the longevity (up to few hours) of acute slice preparations (up to 600μm thick) (Hass H L et al., 1979; Nicoll R A and Alger B E, 1981; Passeraub P A et al., 2003). Here, we report a unique interstitial microfluidic perfusion technique to culture thick (700μm) organotypic brain slices. The design of the custom-made micro-perfusion chamber facilitates laminar, interstitial perfusion of oxygenated nutrient medium throughout the tissue thickness with concomitant removal of depleted medium and catabolites. We examined the utility of this perfusion method to enhance the viability of the thick organotypic brain slice cultures after 2 days and 5 days in vitro (DIV). We investigated the range of amenable flow rates that enhance the viability of 700μm thick organotypic brain slices compared to the unperfused control cultures. Our perfusion method allows up to 84.6% viability (P<0.01) and up to 700μm thickness, even after 5 DIV. Our results also confirm that these cultures are functionally active and have their in vivo cytoarchitecture

  20. Tripled Readout Slices in Multi Time-Point pCASL Using Multiband Look-Locker EPI

    PubMed Central

    Zhang, Ke; Yun, Seong Dae; Shah, N. Jon

    2015-01-01

    Multi time-point pseudo-continuous arterial spin labelling (pCASL) with a Look-Locker EPI readout can sample the signal curve of blood kinetics at multiple time points after the labelling pulse. However, due to signal relaxation of labelled blood, the number of readout slices is limited. The aim of this study is to employ a multiband excitation technique to triple the number of readout slices in multi time-point pCASL. The multiband technique, along with 2-fold in-plane parallel imaging, was incorporated into the Look-Locker EPI for the multi time-point sampling of blood kinetic behaviour following the pCASL labelling scheme. The performance evaluation of the multiband and the single-band techniques were performed on four healthy subjects using a 32-channel head RF coil at 3T. Quantitative perfusion maps were analysed using a combination of labelling with and without flow suppression gradients. The perfusion maps provided by the multiband accelerated multi time-point pCASL were in good agreement with the conventional single-band technique. Multiband acceleration caused SNR loss but offered quantitative perfusion maps in 6.23 min with 18 slices compared with 6 slices within the same time period for the single-band method. As conclusion, the multiband technique can successfully triple the number of readout slices while achieving comparable perfusion data in the same measurement time as the conventional single-band readout. PMID:26544715

  1. Effect of mechanical abrasion on the viability, disruption and germination of spores of Bacillus subtilis

    PubMed Central

    Jones, C.A.; Padula, N.L.; Setlow, P.

    2005-01-01

    Aims To elucidate the factors influencing the sensitivity of Bacillus subtilis spores to killing and disruption by mechanical abrasion, and the mechanism of stimulation of spore germination by abrasion. Methods and Results Spores of B. subtilis strains were abraded by shaking with glass beads in liquid or the dry state, and spore killing, disruption and germination were determined. Dormant spores were more resistant to killing and disruption by abrasion than were growing cells or germinated spores. However, dormant spores of the wild-type strain with or without most coat proteins removed, spores of strains with mutations causing spore coat defects, spores lacking their large depot of dipicolinic acid (DPA) and spores with defects in the germination process exhibited essentially identical rates of killing and disruption by abrasion. When spores lacking all nutrient germinant receptors were enumerated by plating directly on nutrient medium, abrasion increased the plating efficiency of these spores before killing them. Spores lacking all nutrient receptors and either of the two redundant cortex-lytic enzymes behaved similarly in this regard, but the plating efficiency of spores lacking both cortex-lytic enzymes was not stimulated by abrasion. Conclusions Dormant spores are more resistant to killing and disruption by abrasion than are growing cells or germinated spores, and neither the complete coats nor DPA are important in spore resistance to such treatments. Germination is not essential for spore killing by abrasion, although abrasion can trigger spore germination by activation of either of the spore’s cortex-lytic enzymes. Significance and Importance This work provides new insight into the mechanisms of the killing, disruption and germination of spores by abrasion and makes the surprising finding that at least much of the spore coat is not important in spore resistance to abrasion. PMID:16313421

  2. Polyester and epoxy resins: Abrasion resistance. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    Not Available

    1994-06-01

    The bibliography contains citations concerning techniques and materials for enhanced wear and abrasion resistance of polyester and epoxy resins. Topics include test procedures and results, compounds and additives, forming processes, reinforcement effects, and applications. Electrical insulation, linings and coatings for numerous substrates, solar control film glazing material, hoses, material to rebuild worn metal parts, pipes, boats, industrial floor coverings, and ladder rungs are among the applications discussed. Trade name materials and manufacturers are included. (Contains a minimum of 130 citations and includes a subject term index and title list.)

  3. Modelling transfer of Listeria monocytogenes during slicing of 'gravad' salmon.

    PubMed

    Aarnisalo, Kaarina; Sheen, Shiowshuh; Raaska, Laura; Tamplin, Mark

    2007-08-15

    Transfer of a rifampicin-resistant mutant of Listeria monocytogenes from an inoculated slicing blade to slices of 'gravad' salmon (Salmo salar), and from inoculated salmon fillet to the slicing machine and subsequently to slices of uninoculated fillet was studied. The effect of slicing temperature (0 degrees C, 10 degrees C and room temperature), inoculum level (approx. 3, 5 and 8 log CFU/blade), and attachment time of inoculum to blade (10 min and 2.5 h) were investigated and predictive models of the transfer were produced. In the tests of transfer from inoculated blade (5.9-9.0 log CFU/blade) initially 2.5-5.3 log CFU/g was present on the slices, slowly decreasing to an overall average decrease of 1.6+/-0.2 log CFU/g during slicing of 39 slices; the lowest reduction being 1.3 log CFU/g at 0 degrees C. In tests of transfer from contaminated salmon (7.6+/-0.1 log CFU/fillet) to uninoculated blade and further to uninoculated salmon, the reduction in number of L. monocytogenes in slices was 1.5 log CFU/g during slicing of 39 slices. For example 5.3+/-0.3 log CFU/g was transferred to second slice when the inoculum level was 8.4+/-0.4 log CFU/blade, but clearly (p<0.05) lower total number of L. monocytogenes were transferred to slices when the inoculum level was lower, the temperature was colder or the attachment time was longer. There was a progressive exponential reduction in the quantity of L. monocytogenes transferred and, based on statistical parameters, an exponential model (y=ae((-x/b))) fit the data from different test conditions and was suitable for predicting an expected number of L. monocytogenes on the salmon slices. Based on the predicted values, the logarithmic reduction in number of L. monocytogenes in slices was highest at room temperature with an inoculum level of 8.4+/-0.4 log CFU/blade (attachment time 10 min); the other test conditions differed significantly from this (p<0.05). Despite statistically significant differences, in all test conditions

  4. Air abrasion experiments in U-Pb dating of zircon

    USGS Publications Warehouse

    Goldich, S.S.; Fischer, L.B.

    1986-01-01

    Air abrasion of zircon grains can remove metamict material that has lost radiogenic Pb and zircon overgrowths that were added during younger events and thereby improve the precision of the age measurements and permit closer estimates of the original age. Age discordance that resulted from a single disturbance of the U-Pb isotopic decay systems, as had been demonstrated by T.E. Krogh, can be considerably reduced, and, under favorable conditions, the ages brought into concordancy. Two or more events complicate the U-Pb systematics, but a series of abrasion experiments can be helpful in deciphering the geologic history and in arriving at a useful interpretation of the probable times of origin and disturbances. In east-central Minnesota, U.S.A., Penokean tonalite gneiss is dated at 1869 ?? 5 Ma, and sheared granite gneiss is shown to have been a high-level granite intrusion at 1982 ?? 5 Ma in the McGrath Gneiss precursor. Tonalite gneiss and a mafic granodiorite in the Rainy Lake area, Ontario, Canada, are dated at 2736 ?? 16 and 2682 ?? 4 Ma, respectively. The tonalitic phase of the Morton Gneiss, southwestern Minnesota, is dated at 3662 ?? 42 Ma. ?? 1986.

  5. Abrasion Resistant Coating and Method of making the same

    SciTech Connect

    Sordelet, Daniel J.; Besser, Matthew F.

    1999-06-25

    An abrasion resistant coating is created by adding a ductile phase to a brittle matrix phase during spray coating where an Al-Cu-Fe quasicrystalline phase (brittle matrix) and an FeAl intermetallic (ductile phase) are combined. This composite coating produces a coating mostly of quasicrystal phase and an inter-splat layer of the FeAl phase to help reduce porosity and cracking within the coating. Coatings are prepared by plasma spraying unblended and blended quasicrystal and intermetallic powders. The blended powders contain 1, 5, 10 and 20 volume percent of the intermetallic powders. The unblended powders are either 100 volume percent quasicrystalline or 100 volume percent intermetallic; these unblended powders were studied for comparison to the others. Sufficient ductile phase should be added to the brittle matrix to transform abrasive wear mode from brittle fracture to plastic deformation, while at the same time the hardness of the composite should not be reduced below that of the original brittle phase material.

  6. Abrasion resistant coating and method of making the same

    DOEpatents

    Sordelet, Daniel J.; Besser, Matthew F.

    2001-06-05

    An abrasion resistant coating is created by adding a ductile phase to a brittle matrix phase during spray coating where an Al--Cu--Fe quasicrystalline phase (brittle matrix) and an FeAl intermetallic (ductile phase) are combined. This composite coating produces a coating mostly of quasicrystal phase and an inter-splat layer of the FeAl phase to help reduce porosity and cracking within the coating. Coatings are prepared by plasma spraying unblended and blended quasicrystal and intermetallic powders. The blended powders contain 1, 5, 10 and 20 volume percent of the intermetallic powders. The unblended powders are either 100 volume percent quasicrystalline or 100 volume percent intermetallic; these unblended powders were studied for comparison to the others. Sufficient ductile phase should be added to the brittle matrix to transform abrasive wear mode from brittle fracture to plastic deformation, while at the same time the hardness of the composite should not be reduced below that of the original brittle phase material.

  7. Prediction Of Abrasive And Diffusive Tool Wear Mechanisms In Machining

    NASA Astrophysics Data System (ADS)

    Rizzuti, S.; Umbrello, D.

    2011-01-01

    Tool wear prediction is regarded as very important task in order to maximize tool performance, minimize cutting costs and improve the quality of workpiece in cutting. In this research work, an experimental campaign was carried out at the varying of cutting conditions with the aim to measure both crater and flank tool wear, during machining of an AISI 1045 with an uncoated carbide tool P40. Parallel a FEM-based analysis was developed in order to study the tool wear mechanisms, taking also into account the influence of the cutting conditions and the temperature reached on the tool surfaces. The results show that, when the temperature of the tool rake surface is lower than the activation temperature of the diffusive phenomenon, the wear rate can be estimated applying an abrasive model. In contrast, in the tool area where the temperature is higher than the diffusive activation temperature, the wear rate can be evaluated applying a diffusive model. Finally, for a temperature ranges within the above cited values an adopted abrasive-diffusive wear model furnished the possibility to correctly evaluate the tool wear phenomena.

  8. Sliding-gate valve for use with abrasive materials

    DOEpatents

    Ayers, Jr., William J.; Carter, Charles R.; Griffith, Richard A.; Loomis, Richard B.; Notestein, John E.

    1985-01-01

    The invention is a flow and pressure-sealing valve for use with abrasive solids. The valve embodies special features which provide for long, reliable operating lifetimes in solids-handling service. The valve includes upper and lower transversely slidable gates, contained in separate chambers. The upper gate provides a solids-flow control function, whereas the lower gate provides a pressure-sealing function. The lower gate is supported by means for (a) lifting that gate into sealing engagement with its seat when the gate is in its open and closed positions and (b) lowering the gate out of contact with its seat to permit abrasion-free transit of the gate between its open and closed positions. When closed, the upper gate isolates the lower gate from the solids. Because of this shielding action, the sealing surface of the lower gate is not exposed to solids during transit or when it is being lifted or lowered. The chamber containing the lower gate normally is pressurized slightly, and a sweep gas is directed inwardly across the lower-gate sealing surface during the vertical translation of the gate.

  9. Attrition and abrasion models for oil shale process modeling

    SciTech Connect

    Aldis, D.F.

    1991-10-25

    As oil shale is processed, fine particles, much smaller than the original shale are created. This process is called attrition or more accurately abrasion. In this paper, models of abrasion are presented for oil shale being processed in several unit operations. Two of these unit operations, a fluidized bed and a lift pipe are used in the Lawrence Livermore National Laboratory Hot-Recycle-Solid (HRS) process being developed for the above ground processing of oil shale. In two reports, studies were conducted on the attrition of oil shale in unit operations which are used in the HRS process. Carley reported results for attrition in a lift pipe for oil shale which had been pre-processed either by retorting or by retorting then burning. The second paper, by Taylor and Beavers, reported results for a fluidized bed processing of oil shale. Taylor and Beavers studied raw, retorted, and shale which had been retorted and then burned. In this paper, empirical models are derived, from the experimental studies conducted on oil shale for the process occurring in the HRS process. The derived models are presented along with comparisons with experimental results.

  10. Influence of Thin Slice Reconstruction on CT Brain Perfusion Analysis

    PubMed Central

    Bennink, Edwin; Oosterbroek, Jaap; Horsch, Alexander D.; Dankbaar, Jan Willem; Velthuis, Birgitta K.; Viergever, Max A.; de Jong, Hugo W. A. M.

    2015-01-01

    Objectives Although CT scanners generally allow dynamic acquisition of thin slices (1 mm), thick slice (≥5 mm) reconstruction is commonly used for stroke imaging to reduce data, processing time, and noise level. Thin slice CT perfusion (CTP) reconstruction may suffer less from partial volume effects, and thus yield more accurate quantitative results with increased resolution. Before thin slice protocols are to be introduced clinically, it needs to be ensured that this does not affect overall CTP constancy. We studied the influence of thin slice reconstruction on average perfusion values by comparing it with standard thick slice reconstruction. Materials and Methods From 50 patient studies, absolute and relative hemisphere averaged estimates of cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and permeability-surface area product (PS) were analyzed using 0.8, 2.4, 4.8, and 9.6 mm slice reconstructions. Specifically, the influence of Gaussian and bilateral filtering, the arterial input function (AIF), and motion correction on the perfusion values was investigated. Results Bilateral filtering gave noise levels comparable to isotropic Gaussian filtering, with less partial volume effects. Absolute CBF, CBV and PS were 22%, 14% and 46% lower with 0.8 mm than with 4.8 mm slices. If the AIF and motion correction were based on thin slices prior to reconstruction of thicker slices, these differences reduced to 3%, 4% and 3%. The effect of slice thickness on relative values was very small. Conclusions This study shows that thin slice reconstruction for CTP with unaltered acquisition protocol gives relative perfusion values without clinically relevant bias. It does however affect absolute perfusion values, of which CBF and CBV are most sensitive. Partial volume effects in large arteries and veins lead to overestimation of these values. The effects of reconstruction slice thickness should be taken into account when absolute perfusion values are

  11. Comparative study of talc poudrage versus pleural abrasion for the treatment of primary spontaneous pneumothorax†

    PubMed Central

    Moreno-Merino, Sergio; Congregado, Miguel; Gallardo, Gregorio; Jimenez-Merchan, Rafael; Trivino, Ana; Cozar, Fernando; Lopez-Porras, Marta; Loscertales, Jesus

    2012-01-01

    Primary spontaneous pneumothorax is a pathology mainly affecting healthy young patients. Clinical guidelines do not specify the type of pleurodesis that should be conducted, due to the lack of comparative studies on the different techniques. The aim of this study was to compare talc poudrage and pleural abrasion in the treatment of spontaneous pneumothorax. A retrospective comparative study was performed, including 787 patients with primary spontaneous pneumothorax. The 787 patients were classified into two groups: Group A (pleural abrasion) n = 399 and Group B (talc pleurodesis) n = 388. The variables studied were recurrence, surgical time, morbidity and in-hospital length of stay. Statistical analysis was done by an unpaired t-test and Fisher's exact test (SSPS 18.0). Statistically significant differences were observed in the variables: surgical time (A: 46 ± 12.3; B: 37 ± 11.8 min; P < 0.001); length of stay (A: 4.7 ± 2.5; B: 4.3 ± 1.8 days; P = 0.01); apical air camera (A: 25; B: 4; P < 0.001); pleural effusion (A: 6; B: 0; P = 0.05). Talc poudrage shows shorter surgical times and length of stay, and lower re-intervention rates. Morbidity is lower in patients with talc poudrage. Statistically significant differences were not observed in recurrence, persistent air leaks, atelectasis and haemothorax. PMID:22514256

  12. Adaptation of Microplate-based Respirometry for Hippocampal Slices and Analysis of Respiratory Capacity

    PubMed Central

    Schuh, Rosemary A.; Clerc, Pascaline; Hwang, Hyehyun; Mehrabian, Zara; Bittman, Kevin; Chen, Hegang; Polster, Brian M.

    2011-01-01

    Multiple neurodegenerative disorders are associated with altered mitochondrial bioenergetics. Although mitochondrial O2 consumption is frequently measured in isolated mitochondria, isolated synaptic nerve terminals (synaptosomes), or cultured cells, the absence of mature brain circuitry is a remaining limitation. Here we describe the development of a method that adapts the Seahorse Extracellular Flux Analyzer (XF24) for the microplate-based measurement of hippocampal slice O2 consumption. As a first evaluation of the technique, we compared whole slice bioenergetics to previous measurements made with synaptosomes or cultured neurons. We found that mitochondrial respiratory capacity and O2 consumption coupled to ATP synthesis could be estimated in cultured or acute hippocampal slices with preserved neural architecture. Mouse organotypic hippocampal slices oxidizing glucose displayed mitochondrial O2 consumption that was well-coupled, as determined by the sensitivity to the ATP synthase inhibitor oligomycin. However stimulation of respiration by uncoupler was modest (<120% of basal respiration) compared to previous measurements in cells or synaptosomes, although enhanced slightly (to ~150% of basal respiration) by the acute addition of the mitochondrial complex I-linked substrate pyruvate. These findings suggest a high basal utilization of respiratory capacity in slices and a limitation of glucose-derived substrate for maximal respiration. The improved throughput of microplate-based hippocampal respirometry over traditional O2 electrode-based methods is conducive to neuroprotective drug screening. When coupled with cell type-specific pharmacology or genetic manipulations, the ability to efficiently measure O2 consumption from whole slices should advance our understanding of mitochondrial roles in physiology and neuropathology. PMID:21520220

  13. Slicing Method for curved façade and window extraction from point clouds

    NASA Astrophysics Data System (ADS)

    Iman Zolanvari, S. M.; Laefer, Debra F.

    2016-09-01

    Laser scanning technology is a fast and reliable method to survey structures. However, the automatic conversion of such data into solid models for computation remains a major challenge, especially where non-rectilinear features are present. Since, openings and the overall dimensions of the buildings are the most critical elements in computational models for structural analysis, this article introduces the Slicing Method as a new, computationally-efficient method for extracting overall façade and window boundary points for reconstructing a façade into a geometry compatible for computational modelling. After finding a principal plane, the technique slices a façade into limited portions, with each slice representing a unique, imaginary section passing through a building. This is done along a façade's principal axes to segregate window and door openings from structural portions of the load-bearing masonry walls. The method detects each opening area's boundaries, as well as the overall boundary of the façade, in part, by using a one-dimensional projection to accelerate processing. Slices were optimised as 14.3 slices per vertical metre of building and 25 slices per horizontal metre of building, irrespective of building configuration or complexity. The proposed procedure was validated by its application to three highly decorative, historic brick buildings. Accuracy in excess of 93% was achieved with no manual intervention on highly complex buildings and nearly 100% on simple ones. Furthermore, computational times were less than 3 sec for data sets up to 2.6 million points, while similar existing approaches required more than 16 hr for such datasets.

  14. Cotton Seedling Injury and Recovery from Wind Blown Sand Abrasion: I. Duration of Exposure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of acres of crops are exposed to wind blown sand abrasion injury each year and in many instances the damage is thought to be sufficiently severe to require replanting. The goal of this study was to determine the effects of wind blown sand abrasion duration on cotton seedlings. Seedlings of...

  15. Cutting Tools, Files and Abrasives. Pre-Apprenticeship Phase 1 Training.

    ERIC Educational Resources Information Center

    Lane Community Coll., Eugene, OR.

    This self-paced student training module on cutting tools, files, and abrasives is one of a number of modules developed for Pre-apprenticeship Phase 1 Training. Purpose of the module is to enable students to identify and explain the proper use and care of various knives, saws, snips, chisels, and abrasives. The module may contain some or all of the…

  16. Effect of canopy leaf distribution on sand transport and abrasion energy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During times when crop canopies are short or sparse, wind erosion can uncover plant roots, deplete the soil resource, and damage plants by abrasion and desiccation. Few studies have considered the effects of position and number of leaves on sand transport and the distribution of the sand abrasion en...

  17. Potential Use of Abrasive Air-Propelled Agricultural Residues for Weed Control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new postemergence weed control tactic is proposed for organic production systems that results in plant abrasion and death upon assault from abrasive grits propelled by compressed air. Grit derived from granulated walnut shells was delivered by a sand blaster at 517 kPa at distances of 30 to 60 cm ...

  18. Vibrodissociation of Neurons from Rodent Brain Slices to Study Synaptic Transmission and Image Presynaptic Terminals

    PubMed Central

    Jun, Sang Beom; Cuzon Carlson, Verginia; Ikeda, Stephen; Lovinger, David

    2011-01-01

    Mechanical dissociation of neurons from the central nervous system has the advantage that presynaptic boutons remain attached to the isolated neuron of interest. This allows for examination of synaptic transmission under conditions where the extracellular and postsynaptic intracellular environments can be well controlled. A vibration-based technique without the use of proteases, known as vibrodissociation, is the most popular technique for mechanical isolation. A micropipette, with the tip fire-polished to the shape of a small ball, is placed into a brain slice made from a P1-P21 rodent. The micropipette is vibrated parallel to the slice surface and lowered through the slice thickness resulting in the liberation of isolated neurons. The isolated neurons are ready for study within a few minutes of vibrodissociation. This technique has advantages over the use of primary neuronal cultures, brain slices and enzymatically isolated neurons including: rapid production of viable, relatively mature neurons suitable for electrophysiological and imaging studies; superior control of the extracellular environment free from the influence of neighboring cells; suitability for well-controlled pharmacological experiments using rapid drug application and total cell superfusion; and improved space-clamp in whole-cell recordings relative to neurons in slice or cell culture preparations. This preparation can be used to examine synaptic physiology, pharmacology, modulation and plasticity. Real-time imaging of both pre- and postsynaptic elements in the living cells and boutons is also possible using vibrodissociated neurons. Characterization of the molecular constituents of pre- and postsynaptic elements can also be achieved with immunological and imaging-based approaches. PMID:21654624

  19. ORGANOTYPIC BRAIN SLICE CULTURES: A REVIEW

    PubMed Central

    HUMPEL, C.

    2015-01-01

    In vitro cell cultures are an important tool for obtaining insights into cellular processes in an isolated system and a supplement to in vivo animal experiments. While primary dissociated cultures permit a single homogeneous cell population to be studied, there is a clear need to explore the function of brain cells in a three-dimensional system where the main architecture of the cells is preserved. Thus, organotypic brain slice cultures have proven to be very useful in investigating cellular and molecular processes of the brain in vitro. This review summarizes (1) the historical development of organotypic brain slices focusing on the membrane technology, (2) methodological aspects regarding culturing procedures, age of donors or media, (3) whether the cholinergic neurons serve as a model of neurodegeneration in Alzheimer’s disease, (4) or the nigrostriatal dopaminergic neurons as a model of Parkinson’s disease and (5) how the vascular network can be studied, especially with regard to a synthetic blood–brain barrier. This review will also highlight some limits of the model and give an outlook on future applications. PMID:26254240

  20. Copper sensitivity in dorsal hippocampus slices.

    PubMed

    Leiva, J; Palestini, M; Tetas, M; López, J

    2000-04-01

    The action of copper on the pyramidal neurons in CA1 of the hippocampus is little understood. Our main aim was to study the possible interaction of copper on the synaptic network in CA1 pyramidal neurons. We used Wistar rats hippocampus slices in a recording chamber. The population response ("population of spikes") collected by an extracellular micropipette under baseline conditions served as control. Copper, GABA, bicuculline and picrotoxin were delivered in different experimental conditions to the slice. One, 10 and 100 microM of copper concentration decreased significantly the amplitude and duration of the population spikes in relation to the control response. This effect did not show concentration dependency. Copper in bicuculline medium decreased significantly the duration response in relation to the control response and in relation to copper effect in a free bicuculline medium. This phenomenon emphasizes the copper action on the GABA (B) and (C) receptors. Copper in a picrotoxin medium increased significantly the excitability of the response. This new effect suggests that copper acts on non-GABA receptors, an effect that could be detected when the GABA receptors were inactivated. As a result of these findings it appears that, under our experimental conditions, copper generated transient sensitivity changes in pyramidal neurons of CA1 dorsal hippocampus. PMID:10782257

  1. Metabolism of Red Beet Slices I. Effects of Washing 1

    PubMed Central

    Reed, D. J.; Kolattukudy, P. E.

    1966-01-01

    The changes in relative participation of pathways of glucose catabolism in red beet slices during washing have been examined using specifically 14C labeled glucoses. Washing of these slices brings about an increase in participation of the pentose phosphate pathway. The composition of the washing medium influences slightly the extent of change in pathway participation. The activity level of certain enzymes participating in the initial stages of glucose catabolism has been measured in fresh and washed beet slices. Fresh slices which barely metabolized gluconate were found to have very little 6-phosphogluconate dehydrogenase activity. Washing brings about a dramatic increase in 6-phosphogluconate dehydrogenase activity and this increase was accompanied by a marked increase in the ability of the slices to metabolize gluconate. In red beet slices the TPNH generated via pentose phosphate pathway appears to be utilized for biosynthetic reductions rather than as respiratory substrate. PMID:16656302

  2. Hybrid organic/inorganic coatings for abrasion resistance on plastic and metal substrates

    SciTech Connect

    Wen, J.; Jordens, K.; Wilkes, G.L.

    1996-12-31

    Novel abrasion resistant coatings have been successfully prepared by the sol-gel method. These materials are spin coated onto bisphenol-A polycarbonate, diallyl diglycol carbonate resin (CR-39) sheet, aluminum, and steel substrates and are thermally cured to obtain a transparent coating of a few microns in thickness. Following the curing, the abrasion resistance is measured and compared with an uncoated control. It was found that these hybrid organic/inorganic networks partially afford excellent abrasion resistance to the polycarbonate substrates investigated. In addition to having excellent abrasion resistance comparable to current commercial coatings, some newly developed systems are also UV resistant. Similar coating formulations applied to metals can greatly improve the abrasion resistance despite the fact that the coatings are lower in density than their substrates.

  3. Electron Microscopy Abrasion Analysis of Candidate Fabrics for Planetary Space Suit Protective Overgarment Application

    NASA Technical Reports Server (NTRS)

    Hennessy, Mary J.

    1992-01-01

    The Electron Microscopy Abrasion Analysis of Candidate Fabrics for Planetary Space Suit Protective Overgarment Application is in support of the Abrasion Resistance Materials Screening Test. The fundamental assumption made for the SEM abrasion analysis was that woven fabrics to be used as the outermost layer of the protective overgarment in the design of the future, planetary space suits perform best when new. It is the goal of this study to determine which of the candidate fabrics was abraded the least in the tumble test. The sample that was abraded the least will be identified at the end of the report as the primary candidate fabric for further investigation. In addition, this analysis will determine if the abrasion seen by the laboratory tumbled samples is representative of actual EVA Apollo abrasion.

  4. A review of engineering control technology for exposures generated during abrasive blasting operations.

    PubMed

    Flynn, Michael R; Susi, Pam

    2004-10-01

    This literature review presents information on measures for controlling worker exposure to toxic airborne contaminants generated during abrasive blasting operations occurring primarily in the construction industry. The exposures of concern include respirable crystalline silica, lead, chromates, and other toxic metals. Unfortunately, silica sand continues to be widely used in the United States as an abrasive blasting medium, resulting in high exposures to operators and surrounding personnel. Recently, several alternative abrasives have emerged as potential substitutes for sand, but they seem to be underused Some of these abrasives may pose additional metal exposure hazards. In addition, several new and improved technologies offer promise for reducing or eliminating exposures; these include wet abrasive blasting, high-pressure water jetting, vacuum blasting, and automated/robotic systems. More research, particularly field studies, is needed to evaluate control interventions in this important and hazardous operation. PMID:15631059

  5. The identification of a Pliocene time slice(s) for data/model comparison

    NASA Astrophysics Data System (ADS)

    Haywood, A. M.; Dolan, A. M.; Pickering, S.; Dowsett, H. J.; McClymont, E. L.; Prescott, C.; Salzmann, U.; Hill, D. J.; Hunter, S. J.; Lunt, D. J.; Pope, J. O.; Valdes, P. J.

    2012-12-01

    The characteristics of the mid-Pliocene Warm Period (3.264 to 3.025 Ma BP) have been examined using geological proxies and climate models. Whilst there is agreement between models and data, details of regional climate differ. Uncertainties in prescribed forcings and in proxy data, limit the utility of the interval to understand the dynamics of a warmer than present climate or evaluate models. This uncertainty comes, in part, from the reconstruction of a time slab rather than a time slice, where forcings required by climate models can be more adequately constrained. Here we describe the rationale and approach for identifying a time slice(s) for Pliocene environmental reconstruction. A time slice centred on 3.205 Ma BP (3.204 to 3.207 Ma BP) has been identified as a priority for investigation. It is a warm interval characterised by a negative benthic oxygen isotope excursion (0.21-0.23‰) centred on Marine Isotope Stage KM5c (KM5.3). It occurred during a period of orbital forcing which was very similar to present-day. Climate model simulations indicate that proxy temperature estimates are unlikely to be significantly affected by orbital forcing for at least a precession cycle centred on the time slice, with the North Atlantic being an important exception. As a result, uncertainties in the chronological control of proxy records will only be moderately detrimental to the synthesis of temperature data. Furthermore, proxy estimates are already able to restrict the carbon dioxide increase in the atmosphere to <120 ppmv above the pre-industrial concentration, and sea-level rise to ~22 m ± 10 m higher than present-day.

  6. SLICE/MARC-O: Description of Services. Second Revised Edition.

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Libraries, Oklahoma City.

    Following the discussions of: what is SLICE, what is MARC, what is MARC-O, and what is SLICE/MARC-O are descriptions of the five services offered by SLICE/MARC-O. These services are: (1) cataloging data search and print, (2) MARC record and search and copy, (3) standard S.D.I. current awareness, (4) custom S.D.I. current awareness and (5) SLICE…

  7. Test chamber and forensic microscopy investigation of the transfer of brominated flame retardants into indoor dust via abrasion of source materials.

    PubMed

    Rauert, C; Harrad, S; Suzuki, G; Takigami, H; Uchida, N; Takata, K

    2014-09-15

    Brominated flame retardants (BFRs) have been detected in indoor dust in many studies, at concentrations spanning several orders of magnitude. Limited information is available on the pathways via which BFRs migrate from treated products into dust, yet the different mechanisms hypothesized to date may provide an explanation for the range of reported concentrations. In particular, transfer of BFRs to dust via abrasion of particles or fibers from treated products may explain elevated concentrations (up to 210 mg g(-1)) of low volatility BFRs like decabromodiphenyl ether (BDE-209). In this study, an indoor dust sample containing a low concentration of hexabromocyclododecane, or HBCD, (110 ng g(-1) ΣHBCDs) was placed on the floor of an in-house test chamber. A fabric curtain treated with HBCDs was placed on a mesh shelf 3 cm above the chamber floor and abrasion induced using a stirrer bar. This induced abrasion generated fibers of the curtain, which contaminated the dust, and ΣHBCD concentrations in the dust increased to between 4020 and 52 500 ng g(-1) for four different abrasion experiment times. The highly contaminated dust (ΣHBCD at 52 500 ng g(-1)) together with three archived dust samples from various UK microenvironments, were investigated with forensic microscopy techniques. These techniques included Micro X-ray fluorescent spectroscopy, scanning emission microscopy coupled with an energy dispersive X-ray spectrometer, Fourier transform infrared spectroscopy with further BFR analysis on LC-MS/MS. Using these techniques, fibers or particles abraded from a product treated with BFRs were identified in all dust samples, thereby accounting for the elevated concentrations detected in the original dust (3500 to 88 800 ng g(-1) ΣHBCD and 24 000 to 1,438 000 ng g(-1) for BDE-209). This study shows how test chamber experiments alongside forensic microscopy techniques, can provide valuable insights into the pathways via which BFRs contaminate indoor dust. PMID:24984234

  8. Constant mean curvature slicings of Kantowski-Sachs spacetimes

    SciTech Connect

    Heinzle, J. Mark

    2011-04-15

    We investigate existence, uniqueness, and the asymptotic properties of constant mean curvature (CMC) slicings in vacuum Kantowski-Sachs spacetimes with positive cosmological constant. Since these spacetimes violate the strong energy condition, most of the general theorems on CMC slicings do not apply. Although there are in fact Kantowski-Sachs spacetimes with a unique CMC foliation or CMC time function, we prove that there also exist Kantowski-Sachs spacetimes with an arbitrary number of (families of) CMC slicings. The properties of these slicings are analyzed in some detail.

  9. Analysis of Slice Transverse Emittance Evolution ina Photocathode RF Gun

    SciTech Connect

    Huang, Z.; Ding, Y.; Qiang, J.; /LBL, Berkeley

    2007-10-17

    The slice transverse emittance of an electron beam is of critical significance for an x-ray FEL. In a photocathode RF gun, the slice transverse emittance is not only determined by the emission process, but also influenced strongly by the non-linear space charge effect. In this paper, we study the slice transverse emittance evolution in a photocathode RF gun using a simple model that includes effects of RF acceleration, focusing, and space charge force. The results are compared with IMPACT-T space charge simulations and may be used to understand the development of the slice emittance in an RF gun.

  10. High grade abrasive product development from virtified industrial waste

    SciTech Connect

    Blume, R.D.; Drummond, C.H. III; Sarko, A.

    1996-12-31

    Recent developments in environmental legislation, as well as economic incentives such as the increasing cost of landfilling, have led to a paradigm shift away from encapsulation of hazardous waste. The current focus is recycling and product development utilizing industrial waste as raw materials. Current research has targeted the development of high grade abrasive (Vickers hardness (VHN) > 1000 kgF/mm{sup 2}) for blasting and buffing and polishing applications. In addition to product specific physical properties, the developed formulations must also have processing characteristics necessary for vitrification using a high temperature product burner developed by Seiler Pollution Control Systems, as well as the necessary resistance to leaching of EPA regulated hazardous components. Current work has led to the development of formulations with high VHN (950 kgF/mm{sup 2}), acceptable chemical durability, and high mechanical durability utilizing electric arc furnace dust (KO61) and foundry sand as the major components.

  11. Fatigue Testing of Abrasive Water Jet Cut Titanium

    SciTech Connect

    Hovanski, Yuri; Dahl, Michael E.; Williford, Ralph E.

    2009-06-08

    Battelle Memorial Institute as part of its U.S. Department of Energy (USDOE) Contract No. DE-AC05-76RL01830 to operate the Pacific Northwest National Laboratory (PNNL) provides technology assistance to qualifying small businesses in association with a Technology Assistance Program (TAP). Qualifying companies are eligible to receive a set quantity of labor associated with specific technical assistance. Having applied for a TAP agreement to assist with fatigue characterization of Abrasive Water Jet (AWJ) cut titanium specimens, the OMAX Corporation was awarded TAP agreement 09-02. This program was specified to cover dynamic testing and analysis of fatigue specimens cut from titanium alloy Ti-6%Al-4%V via AWJ technologies. In association with the TAP agreement, a best effort agreement was made to characterize fatigue specimens based on test conditions supplied by OMAX.

  12. Microstructure and abrasion resistance of plasma sprayed titania coatings

    NASA Astrophysics Data System (ADS)

    Ctibor, P.; Neufuss, K.; Chraska, P.

    2006-12-01

    Agglomerated titania nanopowder and a “classical” titania were sprayed by the high throughput water-stabilized plasma (WSP) and thoroughly compared. Optical microscopy with image analysis as well as mercury intrusion porosimetry were used for quantification of porosity. Results indicate that the “nano” coatings in general exhibit finer pores than coatings of the “conventional” micron-sized powders. Mechanical properties such as Vickers microhardness and slurry abrasion response were measured and linked to the structural investigation. Impact of the variation in the slurry composition on wear resistance of tested coatings and on character of the wear damage is discussed. The overall results, however, suggest that the “nano” coatings properties are better only for carefully selected sets of spraying parameters, which seem to have a very important impact.

  13. Quantitative modeling of facet development in ventifacts by sand abrasion

    NASA Astrophysics Data System (ADS)

    Várkonyi, Péter L.; Laity, Julie E.; Domokos, Gábor

    2016-03-01

    We use a quantitative model to examine rock abrasion by direct impacts of sand grains. Two distinct mechanisms are uncovered (unidirectional and isotropic), which contribute to the macro-scale morphological characters (sharp edges and flat facets) of ventifacts. It is found that facet formation under conditions of a unidirectional wind relies on certain mechanical properties of the rock material, and we confirm the dominant role of this mechanism in the formation of large ventifacts. Nevertheless small ventifacts may also be shaped to polyhedral shapes in a different way (isotropic mechanism), which is not sensitive to wind characteristics nor to rock material properties. The latter mechanism leads to several 'mature' shapes, which are surprisingly analogous to the morphologies of typical small ventifacts. Our model is also able to explain certain quantitative laboratory and field observations, including quick decay of facet angles of ventifacts followed by stabilization in the range 20-30°.

  14. Improved slicing method for GOSAT cloud detection using TIR spectra

    NASA Astrophysics Data System (ADS)

    Someya, Y.; Imasu, R.; Shiomi, K.; Saitoh, N.; Ota, Y.

    2015-12-01

    Greenhouse gas observing SATellite (GOSAT) is a polar orbiting satellite for greenhouse gas observations and the main sensor, TANSO-FTS, has three near-infrared bands and a thermal infrared (TIR) band which covers a wide spectral region of 5.56 - 14.3 mm with resolution of 0.2 cm-1. The algorithm used in this study was based on a cirrus detection technique called CO2 slicing method, modified as described below. The weighting functions which represent sensitivity profiles were calculated at each channel in the TIR band of GOSAT. The channels were reconstructed as sets of several spectral channels for each height level based on the peak heights of the weighting functions. Subsequently, the channel combinations were optimized based on simulation studies for several temperature profile patterns for each latitude and temperature at 500 hPa. The observed data in 2010 were analyzed using these optimized channels. Global cloud amounts and their seasonal variations were validated using Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data. Results show some differences of cloud amounts and heights between GOSAT and CALIPSO, which might be caused by surface temperature biases, the inverse layer, the difference of sensitivity of sensors, and marine stratocumulus clouds. However, the characteristics of horizontal distributions derived using the slicing method were generally agreed with those obtained from CALIPSO and reported in previous researches. In addition, comparison of cloud top height using collocated data showed good agreement and clouds with optical thickness less than 0.1 are detectable using this method.

  15. Disposal of metal fragments released during polycrystalline slicing by multi-wire saw

    NASA Astrophysics Data System (ADS)

    Boutouchent-Guerfi, N.; Drouiche, N.; Medjahed, S.; Ould-Hamou, M.; Sahraoui, F.

    2016-08-01

    The environmental and economic impacts linked with solar systems are largely based on discharges of slurry generated during the various stages of sawing and cutting ingots. These discharges into the environment are subject to the general regulations on hazardous and special industrial waste disposal. Therefore, they should not be abandoned or burned in open air. The cutting of Silicon ingots leads to the production of Silicon wafers additional costs, losing more than 30% of Silicon material. Abrasive grains (Silicon Carbide) trapped between the wire and the block of Silicon need to be removed by various mechanisms to be later evacuated by slurry fragments. In the interest of decreasing operational costs during polycrystalline ingot slicing at Semiconductors Research Center, and, avoid environmental problems; it is necessary to recover the solar grade Silicon from the Silicon sawing waste. For this reason, the removal of metal fragments has become a preliminary requirement to regenerate the slurry; in addition, the solid phase needs to be separated from the liquid phase after the dissolution PEG with the solvent. In the present study, magnetic separation and centrifugation methods were adopted for metals removal, followed by the analysis of some operating parameters such as: washing time, pH, and initial concentration of Silicon. Finally, analytical, morphological and basic methods were performed in order to evaluate the efficiency of the process undertaken.

  16. Comparison of shear bond strength and surface structure between conventional acid etching and air-abrasion of human enamel.

    PubMed

    Olsen, M E; Bishara, S E; Damon, P; Jakobsen, J R

    1997-11-01

    Recently, air-abrasion technology has been examined for potential applications within dentistry, including the field of orthodontics. The purpose of this study was to compare the traditional acid-etch technique with an air-abrasion surface preparation technique, with two different sizes of abrading particles. The following parameters were evaluated: (a) shear bond strength, (b) bond failure location, and (c) enamel surface preparation, as viewed through a scanning electron microscope. Sixty extracted human third molars were pumiced and divided into three groups of 20. The first group was etched with a 37% phosphoric acid gel for 30 seconds, rinsed for 30 seconds, and dried for 20 seconds. The second and third groups were air-abraded with (a) a 50 microm particle and (b) a 90 microm particle of aluminum oxide, with the Micro-etcher microabrasion machine (Danville Engineering Inc.). All three groups had molar stainless steel orthodontic brackets bonded to the buccal surface of each tooth with Transbond XT bonding system (3M Unitek). A Zwick Universal Testing Machine (Calitek Corp.) was used to determine shear bond strengths. The analysis of variance was used to compare the three groups. The Adhesive Remnant Index (ARI) was used to evaluate the residual adhesive on the enamel after bracket removal. The chi square test was used to evaluate differences in the ARI scores among the groups. The significance for all tests was predetermined at p < or = 0.05. The results indicated that there was a significant difference in shear bond strength among the three groups (p = 0.0001). The Duncan Multiple Range test showed a significant decrease in shear bond strength in the air-abraded groups. The chi square test revealed significant differences among the ARI scores of the acid-etched group and the air-abraded groups (chi(2) = 0.0001), indicating no adhesive remained on the enamel surface after debonding when air-abrasion was used. In conclusion, the current findings indicate that

  17. Cover and Erosion Asymmetry in Saltation-Abrasion

    NASA Astrophysics Data System (ADS)

    Stark, C. P.; Parker, G.

    2014-12-01

    Erosion in bedrock-floored rivers is both driven and limited by the amount of sediment transported along the bed. Some sediment boosts wear rates, whereas too much generates a protective cover. This phenomenon determines the shape of river channels in a variety of landscapes and limits how fast they evolve. Here we reevaluate data from a well-known bedrock wear experiment to throw new light on how the saltation-abrasion process. Instead of a symmetric form for erosion versus sediment flux relative to transport capacity, we find the erosion rate peak shifts towards lower sediment fluxes when blocking of oblique saltation trajectories is taken into account. The theoretical context for this reevaluation is a cover-saltation-abrasion model, based on queueing theory (QT), for bedload transport over a planar bedrock bed. The QT approach provides some clarity in the stochastic treatment of granular impacts and cover, and generates closed-form solutions for wear rate in terms of sediment flux and simplified saltation geometry. Applied to the Sklar & Dietrich (2001) experiments in a very small recirculating flume, the two-parameter QT model fits the observed relation between erosion rate and sediment load, infers sediment flux as a function of load, admits non-negligible wear rates for a mean sediment depth of one grain, i.e., for full cover on average, but also suggests that bedrock erosion is blocked at >=50% instantaneous cover. The QT model makes testable predictions for future laboratory experiments and highlights the need for specific improvements in more comprehensive treatments of bedrock erosion and cover.

  18. Preparation of postsynaptic density fraction from hippocampal slices and proteomic analysis

    SciTech Connect

    Dosemeci, Ayse . E-mail: dosemeca@mail.nih.gov; Tao-Cheng, J.-H.; Vinade, Lucia; Jaffe, Howard

    2006-01-13

    Hippocampal slices offer an excellent experimental system for the study of activity-induced changes in the postsynaptic density (PSD). While studies have documented electrophysiological and structural changes at synapses in response to precise manipulations of hippocampal slices, parallel biochemical and proteomic analyses were hampered by the lack of subcellular fractionation techniques applicable to starting tissue about three orders of magnitude smaller than that used in conventional protocols. Here, we describe a simple and convenient method for the preparation of PSD fractions from hippocampal slices and the identification of its components by proteomic techniques. The 'micro PSD fraction' obtained following two consecutive extractions of a synaptosomal fraction with Triton X-100 shows a significant enrichment in the marker protein PSD-95. Thin section electron microscopy shows PSDs similar to those observed in situ. However, other particulate material, especially myelin, and membrane vesicles are also present. The composition of the PSD fraction from hippocampal slices was analyzed by 2D LC/MS/MS. The proteomic approach which utilizes as little as 10 {mu}g total protein allowed the identification of >100 proteins. Many of the proteins detected in the fraction are the same as those identified in conventional PSD preparations including specialized PSD-scaffolding proteins, signaling molecules, cytoskeletal elements as well as certain contaminants. The results show the feasibility of the preparation of a PSD fraction from hippocampal slices of reasonable purity and of sufficient yield for proteomic analyses. In addition, we show that further purification of PSDs is possible using magnetic beads coated with a PSD-95 antibody.

  19. Slicing the Torus: Obscuring Structures in Quasars

    NASA Astrophysics Data System (ADS)

    Elvis, Martin

    2012-07-01

    Quasars and Active Galactic Nuclei (AGNs) are often obscured by dust and gas. It is normally assumed that the obscuration occurs in an oblate "obscuring torus", that begins at the radius at which the most refractive dust can remain solid. The most famous form of this torus is a donut-shaped region of molecular gas with a large scale-height. While this model is elegant and accounts for many phenomena at once, it does not hold up to detailed tests. Instead the obscuration in AGNs must occur on a wide range of scales and be due to a minimum of three physically distinct absorbers. Slicing the "torus" into these three regions will allow interesting physics of the AGN to be extracted.

  20. Analysis, design and performance evaluation of optical fiber spectrum-sliced WDM systems

    NASA Astrophysics Data System (ADS)

    Arya, Vivek

    This dissertation investigates the design and performance issues of a recently demonstrated technique, termed as spectrum-slicing, for implementing wavelength-division- multiplexing (WDM) in optical fiber systems. Conventional WDM systems employ laser diodes operating at discrete wavelengths as carriers for the different data channels that are to be multiplexed. Spectrum-slicing provides an attractive low-cost alternative to the use of multiple coherent lasers for such WDM applications by utilizing spectral slices of a broadband noise source for the different data channels. The principal broadband noise source considered is the amplified spontaneous emission (ASE) noise from an optical amplifier. Each slice of the spectrum is actually a burst of noise that is modulated individually for a high capacity WDM system. The stochastic nature of the broadband source gives rise to excess intensity noise which results in a power penalty at the receiver. One way to minimize this penalty, as proposed and analyzed for the first time in this work, is to use an optical preamplifier receiver. It is shown that when an optical preamplifier receiver is used, there exists an optimum filter bandwidth which optimizes the detection sensitivity (minimizes the average number of photons/bit) for a given error probability. Moreover the evaluated detection sensitivity represents an order of magnitude (>10 dB) improvement over conventional PIN receiver-based detection techniques for such spectrum-sliced communication systems. The optimum is a consequence of signal energy fluctuations dominating at low values of the signal time bandwidth product (m), and the preamplifier ASE noise dominating at high values of m. Operation at the optimum bandwidth renders the channel error probability to be a strong function of the optical bandwidth, thus providing motivation for the use of forward error correction coding (FEC). System capacity (for BER = 10-12) is shown to be 23 Gb/s without coding, and 75 Gb

  1. Performance evaluation of a 64-slice CT system with z-flying focal spot.

    PubMed

    Flohr, T; Stierstorfer, K; Raupach, R; Ulzheimer, S; Bruder, H

    2004-12-01

    The meanwhile established generation of 16-slice CT systems enables routine sub-millimeter imaging at short breath-hold times. Clinical progress in the development of multidetector row CT (MDCT) technology beyond 16 slices can more likely be expected from further improvement in spatial and temporal resolution rather than from a mere increase in the speed of volume coverage. We present an evaluation of a recently introduced 64-slice CT system (SOMATOM Sensation 64, Siemens AG, Forchheim, Germany), which uses a periodic motion of the focal spot in longitudinal direction (z-flying focal spot) to double the number of simultaneously acquired slices. This technique acquires 64 overlapping 0.6 mm slices per rotation. The sampling scheme corresponds to that of a 64 x 0.3 mm detector, with the goal of improved longitudinal resolution and reduced spiral artifacts. After an introduction to the detector design, we discuss the basics of z-flying focal spot technology (z-Sharp). We present phantom and specimen scans for performance evaluation. The measured full width at half maximum (FWHM) of the thinnest spiral slice is 0.65 mm. All spiral slice widths are almost independent of the pitch, with deviations of less than 0.1 mm from the nominal value. Using a high-resolution bar pattern phantom (CATPHAN, Phantom Laboratories, Salem, NY), the longitudinal resolution can be demonstrated to be up to 15 lp/cm at the isocenter independent of the pitch, corresponding to a bar diameter of 0.33 mm. Longitudinal resolution is only slightly degraded for off-center locations. At a distance of 100 mm from the isocenter, 14 lp/cm can be resolved in the z-direction, corresponding to a bar diameter of 0.36 mm. Spiral "windmill" artifacts presenting as hyper- and hypodense structures around osseous edges are effectively reduced by the z-flying focal spot technique. Cardiac scanning benefits from the short gantry rotation time of 0.33 s, providing up to 83 ms temporal resolution with 2-segment ECG

  2. Distortion-free spectrum sliced microwave photonic signal processor: analysis, design and implementation.

    PubMed

    Li, Liwei; Yi, Xiaoke; Huang, Thomas X H; Minasian, Robert A

    2012-05-01

    A new switchable microwave photonic filter based on a novel spectrum slicing technique is presented. The processor enables programmable multi-tap generation with general transfer function characteristics and offers tunability, reconfigurabiliy, and switchability. It is based on connecting a dispersion controlled spectrum slicing filter after the modulated bipolar broadband light source, which consequently generates multiple spectrum slices with bipolarity, and compensates dispersion induced RF degradation simultaneously within a single device. A detailed theoretical model for this microwave photonic filter design is presented. Experimental results are presented which verify the model, and demonstrate a 33 bipolar-tap microwave filter with significant reduction of passband attenuations at high frequencies. The RF response improvement of the new microwave photonic filter is investigated, for both an ideal linear group delay line and for the experimental fiber delay line that has second order group delay and the results show that this new structure is effective for RF filters with various free spectral range values and spectrum slice bandwidths. Finally, a switchable bipolar filter that has a square-top bandpass filter response with more than 30 dB stopband attenuation that can be switched on/off via software control is demonstrated. PMID:22565771

  3. [Investigation of Region of Interest (ROI) for measurement of slice thickness in Computed Tomography (CT)].

    PubMed

    Nakamura, Shinobu; Kawata, Hidemichi; Nanbu, Ryosuke; Ohkura, Sunao; Hayashida, Kazuya; Hayabuchi, Naofumi

    2010-03-20

    We evaluated an appropriate region of interest (ROI) size for the measurement of full width at half maximum (FWHM) in the bead method (0.1 mm and 0.5 mm diameter; lead) and the microdisk method (0.05 mm thickness and 1.0 mm diameter; tungsten) using multislice computed tomography (CT). The FWHM of preset slice thicknesses 0.625 mm, 1.25 mm, 5.0 mm and 7.5 mm were measured by varying helical pitch, location of measurement [center and off-center of scan field of view (SFOV)] and ROI size, and they were compared with the tolerance stated in the Japanese Industrial Standards (JIS). It was conlcuded that the appropriate ROI size was influenced by preset slice thickness in this study. At the center of SFOV, measurements of FWHM were enabled within the tolerance of the JIS with small variations in all preset slice thicknesses if the ROI sizes were set between 0.4 times and equal to the size of the bead or microdisk indicating the maximum CT value in the series of CT images. At the off-center of SFOV, the tendency of increasing FWHM was confirmed, but it was shown that variations of the off-center in thicker slice thickness were larger regardless of helical pitch when the orbital synchronized helical scan technique was not used. PMID:20379062

  4. Breast mass detection using slice conspicuity in 3D reconstructed digital breast volumes

    NASA Astrophysics Data System (ADS)

    Kim, Seong Tae; Kim, Dae Hoe; Ro, Yong Man

    2014-09-01

    In digital breast tomosynthesis, the three dimensional (3D) reconstructed volumes only provide quasi-3D structure information with limited resolution along the depth direction due to insufficient sampling in depth direction and the limited angular range. The limitation could seriously hamper the conventional 3D image analysis techniques for detecting masses because the limited number of projection views causes blurring in the out-of-focus planes. In this paper, we propose a novel mass detection approach using slice conspicuity in the 3D reconstructed digital breast volumes to overcome the above limitation. First, to overcome the limited resolution along the depth direction, we detect regions of interest (ROIs) on each reconstructed slice and separately utilize the depth directional information to combine the ROIs effectively. Furthermore, we measure the blurriness of each slice for resolving the degradation of performance caused by the blur in the out-of-focus plane. Finally, mass features are extracted from the selected in focus slices and analyzed by a support vector machine classifier to reduce the false positives. Comparative experiments have been conducted on a clinical data set. Experimental results demonstrate that the proposed approach outperforms the conventional 3D approach by achieving a high sensitivity with a small number of false positives.

  5. Quantitative characterization of agglomerate abrasion in a tumbling blender by using the Stokes number approach.

    PubMed

    Willemsz, Tofan A; Nguyen, Tien Thanh; Hooijmaijers, Ricardo; Frijlink, Henderik W; Vromans, Herman; van der Voort Maarschalk, Kees

    2013-03-01

    Removal of microcrystalline cellulose agglomerates in a dry-mixing system (lactose, 100 M) predominantly occurs via abrasion. The agglomerate abrasion rate potential is estimated by the Stokes abrasion (StAbr) number of the system. The StAbr number equals the ratio between the kinetic energy density of the moving powder bed and the work of fracture of the agglomerate. Basically, the StAbr number concept describes the blending condition of the dry-mixing system. The concept has been applied to investigate the relevance of process parameters on agglomerate abrasion in tumbling blenders. Here, process parameters such as blender rotational speed and relative fill volumes were investigated. In this study, the StAbr approach revealed a transition point between abrasion rate behaviors. Below this transition point, a blending condition exists where agglomerate abrasion is dominated by the kinetic energy density of the powder blend. Above this transition point, a blending condition exists where agglomerates show (undesirable) slow abrasion rates. In this situation, the blending condition is mainly determined by the high fill volume of the filler. PMID:23250711

  6. Microstructural effects in abrasive wear. Third annual progress report, August 12, 1983-August 14, 1984

    SciTech Connect

    Kosel, T.H.

    1984-08-14

    The two major goals of the project are to improve our understanding of the mechanisms of carbide removal and of the role of matrix properties in abrasion. In the area of carbide removal mechanisms, progress this year has included completion of the fixed-depth scratch test apparatus and its use to demonstrate the occurrence of gross carbide cracking under fixed-depth conditions; comparable cracking does not occur under fixed-load conditions at a similar mean load. A high-stress abrasion system has been constructed and tested which will facilitate studies of abrasion under conditions similar to those produced by the fixed-depth scratch test system. Analysis of the work on the size effect in abrasion of dual-phase alloys has been completed. The largest single item in this year's proposed work in a study of the abrasion resistance and mechanisms of material removal in model alloys having second-phase particles (SPP's) with varying fracture properties. In the area of the effects of matrix properties on abrasion, the majority of the effort this year has centered on transmission electron microscopy of the subsurface deformation microstructures developed during abrasion.

  7. Relationships Between Abrasive Wear, Hardness, and Surface Grinding Characteristics of Titanium-Based Metal Matrix Composites

    SciTech Connect

    Blau, Peter Julian; Jolly, Brian C

    2009-01-01

    The objective of this work was to support the development of grinding models for titanium metal-matrix composites (MMCs) by investigating possible relationships between their indentation hardness, low-stress belt abrasion, high-stress belt abrasion, and the surface grinding characteristics. Three Ti-based particulate composites were tested and compared with the popular titanium alloy Ti-6Al-4V. The three composites were a Ti-6Al-4V-based MMC with 5% TiB{sub 2} particles, a Ti-6Al-4V MMC with 10% TiC particles, and a Ti-6Al-4V/Ti-7.5%W binary alloy matrix that contained 7.5% TiC particles. Two types of belt abrasion tests were used: (a) a modified ASTM G164 low-stress loop abrasion test, and (b) a higher-stress test developed to quantify the grindability of ceramics. Results were correlated with G-ratios (ratio of stock removed to abrasives consumed) obtained from an instrumented surface grinder. Brinell hardness correlated better with abrasion characteristics than microindentation or scratch hardness. Wear volumes from low-stress and high-stress abrasive belt tests were related by a second-degree polynomial. Grindability numbers correlated with hard particle content but were also matrix-dependent.

  8. Linear abrasion of a titanium superhydrophobic surface prepared by ultrafast laser microtexturing

    NASA Astrophysics Data System (ADS)

    Steele, Adam; Nayak, Barada K.; Davis, Alexander; Gupta, Mool C.; Loth, Eric

    2013-11-01

    A novel method of fabricating titanium superhydrophobic surfaces by ultrafast laser irradiation is reported. The ultrafast laser irradiation creates self-organized microstructure superimposed with nano-scale roughness, after which a fluoropolymer coating is applied to lower the surface energy of the textured surface and achieve superhydrophobicity. The focus of this study is to investigate abrasion effects on this mechanically durable superhydrophobic surface. The mechanical durability is analyzed with linear abrasion testing and microscopy imaging. Linear abrasion tests indicate that these surfaces can resist complete microstructure failure up to 200 abrasion cycles and avoid droplet pinning up to ten abrasion cycles at 108.4 kPa applied pressure, which roughly corresponds to moderate to heavy sanding or rubbing in the presence of abrasive particles. The wear mechanisms are also investigated and the primary mechanism for this system is shown to be abrasive wear with fatigue by repeated plowing. Although these results demonstrate an advancement in mechanical durability over the majority of existing superhydrophobic surfaces, it exemplifies the challenge in creating superhydrophobic surfaces with suitable mechanical durability for harsh applications, even when using titanium.

  9. Characterization and dispersion of pollutant releases from the abrasive blasting of lead paint from steel bridges

    SciTech Connect

    Lee, M.; Rana, B.

    1999-07-01

    The characterization of airborne and spent material for abrasive blasting of steel paint was performed as part of the Environmental Impact Statement for Lead Paint Removal Operations on New York City Department of Transportation Bridges1. Laboratory tests were performed on painted steel components of the Williamsburg Bridge, to determine the sizes of particles typically released into the air as aerosol and onto the ground as bulk material, as a result of accidental releases from abrasive blasting operations. Two of the most commonly used abrasives for paint removal on steel structures, recyclable steel grit and expendable abrasives were subjected to the laboratory tests. The results of the tests were used to determine the percentage of existing paint and abrasive which becomes airborne and the resultant particle size distributions, which were employed in the air quality concentration and deposition modeling for the EIS. Particle size distributions of the airborne material indicated that the profiles of airborne lead and particulate matter have a mean particle size between 15 and 21 microns. Spent abrasives and paint chips that settle on the floor are larger in size with a mean diameter greater than 259 microns, although up to 6% of this material has a mean diameter less than 50 microns. The percentage of paint and expendable abrasives that become airborne as a result of abrasive blasting were estimated to be as high as 9.0 and 12.4%, respectively. Potential release rates were derived for total accumulation (duration of the project), annual, quarterly, 24-hour, and 1-hour time averaging periods for abrasives, lead, and other metals. Pollutant releases were simulated as individual sources at multiple release heights with the Environment Protection Agency's ISC3ST model for six representative bridges near potential places of public exposure.

  10. Rapid manifestation of reactive astrogliosis in acute hippocampal brain slices

    PubMed Central

    Takano, Takahiro; He, Wei; Han, Xiaoning; Wang, Fushun; Xu, Qiwu; Wang, Xiaohai; Oberheim Bush, Nancy Ann; Cruz, Nancy; Dienel, Gerald A.; Nedergaard, Maiken

    2014-01-01

    A flurry of studies over the past decade has shown that astrocytes play a more active role in neural function than previously recognized. Hippocampal slices prepared from young rodent pups have served as a popular model for studying the pathways by which astrocytes participate in synaptic transmission. It is, however, not known how well astrocytes tolerate traumatic injury and hypoxia, which are unavoidable when preparing acute slices. We here show that astrocytes exhibit striking changes in expression of several receptors and structural proteins, including re-expression of the developmental marker nestin within 90 min following preparation of live vibratome slices. Moreover, immunoelectron microscopy showed a 2.7-fold loss of astrocytic processes in acute hippocampal slices prepared from GFAP-GFP reporter mice. A sharp decrease in the number of mitochondria was also noted in acute slices, concurrently with an increase in mitochondrial size. Glycogen content decreased 3-fold upon slice preparation and did not recover despite stable recordings of field EPSC. Analysis of Ca2+ signaling showed that astrocytic responses to purine receptor and mGluR5 agonists differed in slice vs. in vivo. These observations suggest that the functional properties and the fine structure of astrocytes in slices may be reflective of early stages of reactive gliosis and should be confirmed in vivo when possible. PMID:24272704

  11. Rapid manifestation of reactive astrogliosis in acute hippocampal brain slices.

    PubMed

    Takano, Takahiro; He, Wei; Han, Xiaoning; Wang, Fushun; Xu, Qiwu; Wang, Xiaohai; Oberheim Bush, Nancy Ann; Cruz, Nancy; Dienel, Gerald A; Nedergaard, Maiken

    2014-01-01

    A flurry of studies over the past decade has shown that astrocytes play a more active role in neural function than previously recognized. Hippocampal slices prepared from young rodent pups have served as a popular model for studying the pathways by which astrocytes participate in synaptic transmission. It is, however, not known how well astrocytes tolerate traumatic injury and hypoxia, which are unavoidable when preparing acute slices. We here showed that astrocytes exhibit striking changes in expression of several receptors and structural proteins, including re-expression of the developmental marker nestin within 90 min following preparation of live vibratome slices. Moreover, immunoelectron microscopy showed a 2.7-fold loss of astrocytic processes in acute hippocampal slices prepared from glial fibrillary acidic protein-green fluorescent protein reporter mice. A sharp decrease in the number of mitochondria was also noted in acute slices, concurrently with an increase in mitochondrial size. Glycogen content decreased 3-fold upon slice preparation and did not recover despite stable recordings of field excitatory postsynaptic current. Analysis of Ca(2+) signaling showed that astrocytic responses to purine receptor and mGluR5 agonists differed in slice versus in vivo. These observations suggest that the functional properties and the fine structure of astrocytes in slices may be reflective of early stages of reactive gliosis and should be confirmed in vivo when possible. PMID:24272704

  12. PHYSIOLOGICAL CHANGES IN PINEAPPLE SLICES TREATED WITH ANTIBROWNING AGENTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The physiological responses of pineapple slices to antibrowning agents have been studied. Slices were immersed for 2 minutes in solutions of Isoascorbic acid (IAA) 0.1 M, ascorbic acid (AA) 0.05 M or acetyl cysteine (AC) 0.05 M, packaged in polystyrene trays, prior to storage for up to 14 days at 1...

  13. Mathematical Modeling of Thin Layer Microwave Drying of Taro Slices

    NASA Astrophysics Data System (ADS)

    Kumar, Vivek; Sharma, H. K.; Singh, K.

    2016-03-01

    The present study investigated the drying kinetics of taro slices precooked in different medium viz water (WC), steam (SC) and Lemon Solution (LC) and dried at different microwave power 360, 540 and 720 W. Drying curves of all precooked slices at all microwave powers showed falling rate period along with a very short accelerating period at the beginning of the drying. At all microwave powers, higher drying rate was observed for LC slices as compared to WC and SC slices. To select a suitable drying curve, seven thin-layer drying models were fitted to the experimental data. The data revealed that the Page model was most adequate in describing the microwave drying behavior of taro slices precooked in different medium. The highest effective moisture diffusivity value of 2.11 × 10-8 m2/s was obtained for LC samples while the lowest 0.83 × 10-8 m2/s was obtained for WC taro slices. The activation energy (E a ) of LC taro slices was lower than the E a of WC and SC taro slices.

  14. Modeling surface transfer of L. monocytogenes on salami during slicing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes has been implicated in several listeriosis outbreaks linked to the consumption of pre-sliced ready-to-eat (RTE) deli meats, which has drawn considerable attention in regard to possible cross-contamination during slicing operation at retail and food service environment. Salami...

  15. Target recognition for ladar range image using slice image

    NASA Astrophysics Data System (ADS)

    Xia, Wenze; Han, Shaokun; Wang, Liang

    2015-12-01

    A shape descriptor and a complete shape-based recognition system using slice images as geometric feature descriptor for ladar range images are introduced. A slice image is a two-dimensional image generated by three-dimensional Hough transform and the corresponding mathematical transformation. The system consists of two processes, the model library construction and recognition. In the model library construction process, a series of range images are obtained after the model object is sampled at preset attitude angles. Then, all the range images are converted into slice images. The number of slice images is reduced by clustering analysis and finding a representation to reduce the size of the model library. In the recognition process, the slice image of the scene is compared with the slice image in the model library. The recognition results depend on the comparison. Simulated ladar range images are used to analyze the recognition and misjudgment rates, and comparison between the slice image representation method and moment invariants representation method is performed. The experimental results show that whether in conditions without noise or with ladar noise, the system has a high recognition rate and low misjudgment rate. The comparison experiment demonstrates that the slice image has better representation ability than moment invariants.

  16. Characterization of nanoparticles from abrasive waterjet machining and electrical discharge machining processes.

    PubMed

    Ling, Tsz Yan; Pui, David Y H

    2013-11-19

    Abrasive Waterjet Machining (AWM) and Electrical Discharge Machining (EDM) processes are found to produce nanoparticles during operation. Impacts of engineered nanoparticles released to the environment and biological system have caused much concern. Similarly, the nanoparticles unintentionally produced by the AWM and EDM can lead to comparable effects. By application of the Nanoparticle Tracking Analysis (NTA) technique, the size distribution and concentration of nanoparticles in the water used in AWM and EDM were measured. The particles generally have a peak size of 100-200 nm. The filtration systems of the AWM and EDM processes were found to remove 70% and 90% the nanoparticles present, respectively. However, the particle concentration of the filtered water from the AWM was still four times higher than that found in regular tap water. These nanoparticles are mostly agglomerated, according to the microscopy analysis. Using the electron dispersive spectroscopy (EDS) technique, the particles are confirmed to come from the debris of the materials cut with the equipment. Since AWM and EDM are widely used, the handling and disposal of used filters collected with nanoparticles, release of nanoparticles to the sewer, and potential use of higher performance filters for these processes will deserve further consideration. PMID:24144041

  17. Optical-model abrasion cross sections for high-energy heavy ions

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.

    1981-01-01

    Within the context of eikonal scattering theory, a generalized optical model potential approximation to the nucleus-nucleus multiple scattering series is used in an abrasion-ablation collision model to predict abrasion cross sections for relativistic projectile heavy ions. Unlike the optical limit of Glauber theory, which cannot be used for very light nuclei, the abrasion formalism is valid for any projectile target combination at any incident kinetic energy for which eikonal scattering theory can be utilized. Results are compared with experimental results and predictions from Glauber theory.

  18. Plasma-polymerized coating for polycarbonate: Single-layer, abrasion resistant, and antireflection

    NASA Technical Reports Server (NTRS)

    Wydeven, Theodore

    1991-01-01

    Plasma-polymerized vinyl trimethoxy silane films were deposited on transparent polycarbonate substrates. The adherent, clear films protected the substrates from abrasion and also served as antireflection coatings. Post-treatment of the vinyl trimethoxy silane films in an oxygen glow discharge further improved their abrasion resistance. The coatings were characterized by elemental analysis of the bulk, ESCA analysis of the surface, transmission, thickness, abrasion resistance, haze, and adhesion. This patented process is currently used by the world's largest manufacturers of non-prescription sunglasses to protect the plastic glasses from scratching and thereby to increase their useful lifetime.

  19. Optical-model abrasion cross sections for high-energy heavy ions

    SciTech Connect

    Townsend, L.W.

    1981-07-01

    Within the context of eikonal scattering theory, a generalized optical model potential approximation to the nucleus-nucleus multiple scattering series is used in an abrasion-ablation collision model to predict abrasion cross sections for relativistic projectile heavy ions. Unlike the optical limit of Glauber theory, which cannot be used for very light nuclei, the abrasion formalism is valid for any projectile target combination at any incident kinetic energy for which eikonal scattering theory can be utilized. Results are compared with experimental results and predictions from Glauber theory.

  20. Target correlation effects on neutron-nucleus total, absorption, and abrasion cross sections

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Townsend, Lawrence W.; Wilson, John W.

    1991-01-01

    Second order optical model solutions to the elastic scattering amplitude were used to evaluate total, absorption, and abrasion cross sections for neutron nucleus scattering. Improved agreement with experimental data for total and absorption cross sections is found when compared with first order (coherent approximation) solutions, especially below several hundred MeV. At higher energies, the first and second order solutions are similar. There are also large differences in abrasion cross section calculations; these differences indicate a crucial role for cluster knockout in the abrasion step.

  1. Abrasion of heavy-duty coated steel pipes by sediment transport

    SciTech Connect

    Kariyazono, Yoshihisa; Miyajima, Yoshihiro; Sato, Koichi; Yamashita, Toshihiko, Yamashita; Saeki, Hiroshi

    1994-12-31

    Heavy-duty coatings are standard treatment for steel pipe piles in coastal zones to prevent corrosion. Large amounts of sand sometimes drift around piles by the action of waves. Coatings undergo abrasion by collision of sand particles. Authors carried out experiments by a large scale U-shaped tube which generated a strong oscillatory flow with sand drift and numerical analysis of collision of the particles. Authors found out the abrasion rate of pile is nearly proportional to the collision energy of the particles. Abrasion rate of polyethylene and elastic polyurethane coatings were lower than those of other materials.

  2. Abrasive wear by coal-fueled diesel engine and related particles

    SciTech Connect

    Ives, L.K.

    1992-09-01

    The development of commercially viable diesel engines that operate directly on pulverized coal-fuels will require solution to the problem of severe abrasive wear. The purpose of the work described in this report was to investigate the nature of the abrasive wear problem. Analytical studies were carried out to determine the characteristics of the coal-fuel and associated combustion particles responsible for abrasion. Laboratory pinon-disk wear tests were conducted on oil-particle mixtures to determine the relationship between wear rate and a number of different particle characteristics, contact parameters, specimen materials properties, and other relevant variables.

  3. A survey of program slicing for software engineering

    NASA Technical Reports Server (NTRS)

    Beck, Jon

    1993-01-01

    This research concerns program slicing which is used as a tool for program maintainence of software systems. Program slicing decreases the level of effort required to understand and maintain complex software systems. It was first designed as a debugging aid, but it has since been generalized into various tools and extended to include program comprehension, module cohesion estimation, requirements verification, dead code elimination, and maintainence of several software systems, including reverse engineering, parallelization, portability, and reuse component generation. This paper seeks to address and define terminology, theoretical concepts, program representation, different program graphs, developments in static slicing, dynamic slicing, and semantics and mathematical models. Applications for conventional slicing are presented, along with a prognosis of future work in this field.

  4. Seamless Ligation Cloning Extract (SLiCE) cloning method.

    PubMed

    Zhang, Yongwei; Werling, Uwe; Edelmann, Winfried

    2014-01-01

    SLiCE (Seamless Ligation Cloning Extract) is a novel cloning method that utilizes easy to generate bacterial cell extracts to assemble multiple DNA fragments into recombinant DNA molecules in a single in vitro recombination reaction. SLiCE overcomes the sequence limitations of traditional cloning methods, facilitates seamless cloning by recombining short end homologies (15-52 bp) with or without flanking heterologous sequences and provides an effective strategy for directional subcloning of DNA fragments from bacterial artificial chromosomes or other sources. SLiCE is highly cost-effective and demonstrates the versatility as a number of standard laboratory bacterial strains can serve as sources for SLiCE extract. We established a DH10B-derived E. coli strain expressing an optimized λ prophage Red recombination system, termed PPY, which facilitates SLiCE with very high efficiencies. PMID:24395368

  5. Organotypic slice culture of the hypothalamic paraventricular nucleus of rat

    PubMed Central

    Cho, Eun Seong; Lee, So Yeong; Park, Jae-Yong; Hong, Seong-Geun

    2007-01-01

    Organotypic slice cultures have been developed as an alternative to acute brain slices because the neuronal viability and synaptic connectivity in these cultures can be preserved well for a prolonged period of time. This study evaluated a stationary organotypic slice culture developed for the hypothalamic paraventricular nucleus (PVN) of rat. The results showed that the slice cultures maintain the typical shape of the nucleus, the immunocytochemical signals for oxytocin, vasopressin, and corticotropin-releasing hormone, and the electrophysiological properties of PVN neurons for up to 3 weeks in vitro. The PVN neurons in the culture expressed the green fluorescent protein gene that had been delivered by the adenoviral vectors. The results indicate that the cultured slices preserve the properties of the PVN neurons, and can be used in longterm studies on these neurons in vitro. PMID:17322769

  6. Surface assessment and modification of concrete using abrasive blasting

    NASA Astrophysics Data System (ADS)

    Millman, Lauren R.

    Composite systems are applied to concrete substrates to strengthen and extend the service life. Successful restoration or rehabilitation requires surface preparation prior to the application of the overlay. Surface coatings, waterproofing systems, and other external surface applications also require surface preparation prior to application. Abrasive blast media is often used to clean and uniformly roughen the substrate. The appropriate surface roughness is necessary to facilitate a strong bond between the existing substrate and overlay. Thus, surface modification using abrasive blast media (sand and dry ice), their respective environmental effects, surface roughness characterization prior to and after blasting, and the adhesion between the substrate and overlay are the focus of this dissertation. This dissertation is comprised of an introduction, a literature review, and four chapters, the first of which addresses the environmental effects due to abrasive blasting using sand, water, and dry ice. The assessment considered four response variables: carbon dioxide (CO2) emissions, fuel and energy consumption, and project duration. The results indicated that for sand blasting and water jetting, the primary factor contributing to environmental detriment was CO22 emissions from vehicular traffic near the construction site. The second chapter is an analysis of the International Concrete Repair Institute's (ICRI) concrete surface profiles (CSPs) using 3-D optical profilometry. The primary objective was to evaluate the suitability of approximating the 3-D surface (areal) parameters with those extracted from 2-D (linear) profiles. Four profile directions were considered: two diagonals, and lines parallel and transverse to the longitudinal direction of the mold. For any CSP mold, the estimation of the 3-D surface roughness using a 2-D linear profile resulted in underestimation and overestimation errors exceeding 50%, demonstrating the inadequacy of 2-D linear profiles to

  7. Dental Abrasion of Incisor caused by a Babies' Dummy Clip: A Case Report.

    PubMed

    Doğramacı, Esma J; Rossi-Fedele, Giampiero

    2015-09-01

    Tooth surface loss (TSL), the non-carious loss of tooth tissue, is considered pathological if the teeth involved experience sensitivity and pain, are functionally compromised or they detract from the patient's appearance. TSL is a common clinical finding in many patient groups, although differences between the primary and permanent dentition contribute to TSL occurring at a faster rate and with worse outcomes in the primary dentition. This case report presents localized abrasion and associated apical periodontitis affecting a single primary tooth in a 2-year-old infant following the misuse of a babies' dummy clip whilst teething. Abrasion is rare in the primary dentition. CPD/CLINICAL RELEVANCE: This article highlights an unusual presentation of dental abrasion affecting the primary dentition caused by a previously unreported foreign object; abrasion in this case was a side-effect of soothing the discomfort of teething. PMID:26630866

  8. Abrasion resistance of biaxially oriented polypropylene films coated with nanocomposite hard coatings

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Zhu, Yaofeng; Fu, Yaqin

    2013-11-01

    KMnO4-treated, functionalized, biaxially oriented polypropylene (BOPP) films coated with nano-silica hybrid material were synthesized. The abrasion resistance of the films was examined using a reciprocating fabric abrasion tester. Functional groups were confirmed by Fourier-transform infrared spectroscopy. Contact angle measurements were performed on the BOPP film surface to quantify the effectiveness of the functionalization. Results indicate that the abrasion resistance and roughness of the composite film were significantly affected by the modification of the BOPP film. Water surface contact angle of the modified BOPP films decreased from 90.1° to 71.4°,when KMnO4 concentration increased from 0 M to 0.25 M. Wettability of the BOPP films clearly improved after KMnO4 treatment. Abrasion resistance of the functionalized films coated with hybrid materials improved by 27.4% compared with that of the original film.

  9. Abrasion and deformed layer formation of manganese-zinc ferrite in sliding contact with lapping tapes

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.; Tanaka, K.

    1986-01-01

    Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and the deformed layers produced in single-crystal Mn-Zn ferrite simulated heads during contact with lapping tapes. The crystaline state of the head is changed drastically during the abrasion process. Crystalline states ranging from nearly amorphous to highly textured polycrystalline can be produced on the wear surface of a single-crystal Mn-Zn ferrite head. The total thickness of the deformed layer was approximately 0.8 microns. This thickness increased as the load and abrasive grit size increased. The anisotropic wear of the ferrite was found to be inversely proportional to the hardness of the wear surface. The wear was lower in the order 211 111 10 0110. The wear of the ferrite increased markedly with an increase in sliding velocity and abrasive grit size.

  10. Cracks in glass electrical connector headers removed by dry blasting with fine abrasive

    NASA Technical Reports Server (NTRS)

    Eckert, R. W.

    1967-01-01

    Cracking that causes pressure leakage in glass connector headers can be alleviated by manipulating the pin bridgewire connectors. This initiates the surface and meniscus cracks. Dry blasting the header surface with a fine abrasive then removes the cracks.

  11. Surface roughness and gloss of current CAD/CAM resin composites before and after toothbrush abrasion.

    PubMed

    Koizumi, Hiroyasu; Saiki, Osamu; Nogawa, Hiroshi; Hiraba, Haruto; Okazaki, Tomoyo; Matsumura, Hideo

    2015-01-01

    The purpose of this study was to evaluate the gloss and surface roughness behaviors of newly developed CAD/CAM composite blocks with different filler contents and characteristics. The gloss and surface roughness were quantified before and after a toothbrush dentifrice abrasion test; the results were compared to the gloss and surface roughness of a ceramic CAD/CAM block. Knoop hardness was determined before abrasion test. The results were analyzed by ANOVA, Tukey HSD, and Dunnett t test (p<0.05). The rank order of Knoop hardness was as follows: Vita Mark II>Vita Enamic>Gradia block>Shofu Block HC, Lava Ultimate≥Katana Avencia block≥Cerasmart. After toothbrush abrasion, a significant difference in the gloss unit was detected between the Shofu Block HC material and the ceramic block. The Ra and Rz of the Cerasmart and Shofu Block HC materials were significantly larger than those of the ceramic block after toothbrush abrasion. PMID:26632238

  12. Sliced Inverse Regression for Time Series Analysis

    NASA Astrophysics Data System (ADS)

    Chen, Li-Sue

    1995-11-01

    In this thesis, general nonlinear models for time series data are considered. A basic form is x _{t} = f(beta_sp{1} {T}X_{t-1},beta_sp {2}{T}X_{t-1},... , beta_sp{k}{T}X_ {t-1},varepsilon_{t}), where x_{t} is an observed time series data, X_{t } is the first d time lag vector, (x _{t},x_{t-1},... ,x _{t-d-1}), f is an unknown function, beta_{i}'s are unknown vectors, varepsilon_{t }'s are independent distributed. Special cases include AR and TAR models. We investigate the feasibility applying SIR/PHD (Li 1990, 1991) (the sliced inverse regression and principal Hessian methods) in estimating beta _{i}'s. PCA (Principal component analysis) is brought in to check one critical condition for SIR/PHD. Through simulation and a study on 3 well -known data sets of Canadian lynx, U.S. unemployment rate and sunspot numbers, we demonstrate how SIR/PHD can effectively retrieve the interesting low-dimension structures for time series data.

  13. Thin-slice perception develops slowly.

    PubMed

    Balas, Benjamin; Kanwisher, Nancy; Saxe, Rebecca

    2012-06-01

    Body language and facial gesture provide sufficient visual information to support high-level social inferences from "thin slices" of behavior. Given short movies of nonverbal behavior, adults make reliable judgments in a large number of tasks. Here we find that the high precision of adults' nonverbal social perception depends on the slow development, over childhood, of sensitivity to subtle visual cues. Children and adult participants watched short silent clips in which a target child played with Lego blocks either in the (off-screen) presence of an adult or alone. Participants judged whether the target was playing alone or not; that is, they detected the presence of a social interaction (from the behavior of one participant in that interaction). This task allowed us to compare performance across ages with the true answer. Children did not reach adult levels of performance on this task until 9 or 10 years of age, and we observed an interaction between age and video reversal. Adults and older children benefitted from the videos being played in temporal sequence, rather than reversed, suggesting that adults (but not young children) are sensitive to natural movement in social interactions. PMID:22417920

  14. Plasma polymerized coating for polycarbonate - Single layer, abrasion resistant, and antireflection

    NASA Technical Reports Server (NTRS)

    Wydeven, T.

    1977-01-01

    Plasma polymerized vinyltrimethoxy silane films were deposited on transparent polycarbonate substrates. The adherent, clear films protected the substrates from abrasion and also served as antireflection coatings. Posttreatment of the vinyltrimethoxy silane films in an oxygen glow discharge further improved the abrasion resistance. ESCA (electron spectroscopy for chemical analysis) and IR transmission spectra of some films were recorded, and an elemental analysis of the films was obtained.

  15. Gingival abrasion and plaque removal with manual versus electric toothbrushing.

    PubMed

    Niemi, M L; Ainamo, J; Etemadzadeh, H

    1986-08-01

    A clinical trial was designed to test the relative numbers of gingival lesions caused during standardized brushing of the teeth of 22 volunteer dental nurse students with a manual soft multitufted, a manual soft V-shaped, and an electric toothbrush. First, the left or the right side of the jaws of each subject was brushed by a dental hygienist using the manual V-shaped or the electric brush, and the other side using the manual multitufted brush. At the 2nd brushing 1 week later, the same hygienist used the multitufted brush for brushing the side contralateral to the one in which it was used the 1st week and the V-shaped manual brush instead of the electric and vice versa. After each brushing, the number of new gingival lesions was recorded and the cleansing effect evaluated by assessment of the amount of remaining plaque. This examiner was unaware of the type of brush used. The V-shaped manual toothbrush was found to have caused more gingival abrasion than the electric toothbrush (P less than 0.005) and a similar difference was found between the multitufted manual and the electric toothbrush (P less than 0.05). There was no clinically significant difference between the plaque removing effects of the 3 brushes tested. PMID:3463575

  16. Biodegradation and abrasive wear of nano restorative materials.

    PubMed

    de Paula, A B; Fucio, S B P; Ambrosano, G M B; Alonso, R C B; Sardi, J C O; Puppin-Rontani, R M

    2011-01-01

    The purpose of this study was to evaluate the biomechanical degradation of two nanofilled restorative materials (a resin-modified glass ionomer, Ketac N100 and a composite, Filtek Z350), compared with conventional materials (Vitremer and TPH Spectrum). Twenty specimens obtained from each material were divided into two storage groups (n=10): relative humidity (control) and Streptococcus mutans biofilm (biodegradation). After 7 days of storage, roughness values (Ra) and micrographs by scanning electron microscopy (SEM) were obtained. In a second experimental phase, the specimens previously subjected to biodegradation were fixed to the tooth-brushing device and abraded via toothbrushes, using dentifrice slurry (mechanical degradation). Next, these specimens were washed, dried, and reassessed by roughness and SEM. The data were submitted to repeated measures three-way analysis of variance (ANOVA) and Tukey tests (p<0.05). There was statistically significant interaction among factors: material, storage (humidity/biofilm), and abrasion (before/after). After biodegradation (S mutans biofilm storage), Ketac N100 presented the highest Ra values. Concerning bio plus mechanical challenge, TPH Spectrum, Ketac N100, and Vitremer presented the undesirable roughening of their surfaces, while the nano composite Filtek Z350 exhibited the best resistance to cumulative challenges proposed. The degraded aspect after biodegradation and the exposure of fillers after mechanical degradation were visualized in micrographs. This study demonstrated that the nanotechnology incorporated in restorative materials, as in composite resin and resin-modified glass ionomer, was important for the superior resistance to biomechanical degradation. PMID:21913859

  17. Evaluation of Multilayer Cloud Detection Using a MODIS CO2-Slicing Algorithm With CALIPSO-CloudSat Measurements

    NASA Technical Reports Server (NTRS)

    Viudez-Mora, Antonio; Kato, Seiji

    2015-01-01

    This work evaluates the multilayer cloud (MCF) algorithm based on CO2-slicing techniques against CALISPO-CloudSat (CLCS) measurement. This evaluation showed that the MCF underestimates the presence of multilayered clouds compared with CLCS and are retrained to cloud emissivities below 0.8 and cloud optical septs no larger than 0.3.

  18. Dressing of diamond grinding wheels by abrasive water jet for freeform optical surface grinding

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Yao, Peng; Li, Chengwu; Huang, Chuanzhen; Wang, Jun; Zhu, Hongtao; Liu, Zengwen

    2014-08-01

    During the ultra-precision grinding of a large aperture mirror made of RB-SiC, the grinding wheel becomes dull rapidly, which will lead to an increase of grinding force and a decrease of grinding ratio. In this paper, diamond grinding sticks were dressed with micro SiC abrasive water jet and water jet. Through single factorial experiments, the influence of jet pressure on the dressing performance was investigated. To analyze and evaluate the effect of dressing quantitatively, the 3D roughness and the wheel topography were measured and compared with laser scanning confocal microscope before and after dressing. The experimental results show that the abrasive grains are well protruded from binder and the distribution of the abrasive grains becomes uniform after dressing by abrasive water jet when the dressing parameters are properly selected. The dressing performance of abrasive water jet is much better than water jet. For dressing ultra-fine grit size wheels, the abrasive size of the jet should be smaller than the wheel grit size to achieve a better result. The jet pressure is an obvious influence factor of the surface topography.

  19. An energetic approach to abrasive wear of a martensitic stainless steel

    SciTech Connect

    Pamuk, U.; Baydogan, M.; Niluefer, B.; Cimenoglu, H.

    2000-04-01

    Abrasive wear is the most common type of wear that causes failure of machine elements. Examinations of abraded surfaces revealed presence of embedded particles and grooves elongated along the sliding direction. This indicates that, there are two sequential stages of an abrasion process. In the first stage, asperities on the hard surface and/or hard abrasive grains penetrate into the soft material surface and then in the second stage, they grind the surface in the sliding direction. Therefore, indentation and scratching of an indenter, which can be realized by hardness and scratch tests, can simulate the damage produced on the abraded surface. On the basis of this simulation, an energetic model is proposed for abrasive wear in the present study. In this study, abrasive wear behavior of a martensitic stainless steel is examined by hardness and scratch tests. The results of tests were evaluated to estimate the work done during abrasion and to find out the dimensional wear coefficient according to the model proposed above.

  20. A correlation between abrasion resistance and other properties of some acrylic resins used in dentistry.

    PubMed

    Harrison, A; Huggett, R; Handley, R W

    1979-01-01

    This investigation studies the relationship of hardness, elastic modulus and scratch width as dependent variables to the abrasion resistance of twenty-three dental acrylic resins. The multiple correlation R, when all three variables are used as predictors, is 0.727. Because of the significant intercorrelations between the variables themselves a stepwise multiple regression analysis showed hardness as a redundant variable. Abrasive wear can be estimated from the following equation Abrasive wear = 806.1 - 0.1498 modulus + 0.681 scratch width (R = 0.725; standard deviation of estimate +/- 50.8) The deletion of scratch width does not appreciably reduce the standard deviation of the estimate: Abrasive wear = 1063.4 - 0.2055 modulus (r = 0.683; standard deviation of estimate +/- 50.3) The method of curing the specimens conformed to the respective manufacturers' instructions. Abrasion and scratch tests were performed using methods developed by the authors and previously described in the literature, whereas the hardness and elastic modulus results were devised from standard test procedures. Further research is currently in progress to improve the predictive power of abrasion resistance with additional new variables. PMID:429382

  1. Two-Phase Abrasion in Eolian Transport of Gypsum Sand, White Sands NM

    NASA Astrophysics Data System (ADS)

    Shaw, S.; Jerolmack, D. J.; Miller, K. L.

    2014-12-01

    Downstream rounding of grains is consistently observed in natural sediment transport settings. A recent theory put forth by Domokos et al. (2014) attributes particle rounding and size reduction to a geometric curvature-driven abrasion process. This process occurs in two phases, in which irregularly shaped or angular particles round to convex shapes with negligible change in axis dimension, then slowly reduce in particle diameter. Miller et al (in review) establish the existence of two-phase abrasion in the natural setting of a fluvial gravel stream. This study examines field samples from White Sands, NM to investigate the presence of two-phase abrasion in a different, non-idealized natural environment - a high-energy, eolian gypsum dunefield. Analysis of grain shapes from White Sands confirms the two-phase abrasion process, dependent upon mode of sediment transport. We find that large sand grains carried in saltation bed load transport exhibit shape change indicative of two-phase abrasion, while smaller particles carried in suspension do not. We observe rapid shape change in bed load particles approaching a convex shape, followed by slower reduction in grain axis dimensions. Confirmation of this process in a natural, non-idealized setting establishes two-phase abrasion as a general application for bed load transport.

  2. A light-scattering study of Al2O3 abrasives of various grit sizes

    NASA Astrophysics Data System (ADS)

    Heinson, Yuli W.; Chakrabarti, Amitabha; Sorensen, Christopher M.

    2016-09-01

    We report light scattering phase function measurements for irregularly shaped Al2O3 abrasive powders of various grit sizes. Q-space analysis is applied to the angular scattering to reveal a forward scattering regime, Guinier regime, power law regime with quantifiable exponents, and an enhanced backscattering regime. The exponents of the power laws for Al2O3 abrasives decrease with increasing internal coupling parameter ρ ‧ , which is in agreement with previous observations for other irregular particles. Unlike other dust particles previously studied showing single power laws under Q-space analysis, the largest three abrasives, for which ρ ‧ ≳ 100 , showed a kink in the power law, which is possibly due to the higher degree of symmetry for the abrasives than for all the particles studied previously. Direct comparison of the 1200, 1000, and 800 grit abrasive scattering to scattering by corresponding spheres shows that the scatterings approximately coincide at the spherical particle qR ≃ ρ ‧ crossover point. Furthermore, the scattering at the maximum qR = 2 kR by the irregularly shaped abrasives is close to the geometric centers of the glories of the spheres.

  3. Effect of Intercritical Heat Treatment on the Abrasive Wear Behaviour of Plain Carbon Dual Phase Steel

    NASA Astrophysics Data System (ADS)

    Manoj, M. K.; Pancholi, V.; Nath, S. K.

    Dual phase (DP) steels have been prepared from low carbon steel (0.14% C) at intercritical temperature 740°C and time is varied from 1 minute to 30 minutes followed by water quenching. These steels have been characterized by optical microscopy, FE-SEM, hardness measurements, tensile properties and electron backscattered diffraction (EBSD) studies. Tensile properties of a typical dual phase steel are found to be 805 MPa ultimate tensile strength with 18% total elongation. Martensite volume fraction of D P steel (determined by EBSD technique) prepared at 740°C for 6 minutes is found to be 10.2% and the grain size of ferrite and martensite found to be 14.39 micron and 1.05 microns respectively. Abrasive wear resistance of dual phase steels has been determined by pin on drum wear testing machine. DP steels have been found to be 25% more wear resistant than that of normalized steel. Short intercritical heating time followed by water quenching gives higher wear resistance by virtue of smaller and well dispersed martensite island in the matrix of ferrite.

  4. Local T2 distribution measurements with DANTE-Z slice selection

    NASA Astrophysics Data System (ADS)

    Petrov, Oleg V.; Balcom, Bruce J.

    2012-02-01

    A CPMG pulse sequence incorporated with a DANTE-Z slice selection scheme for measuring spatially-resolved T2 distributions has been presented. The DANTE-Z pulse train with sinc-modulated pulses selects a single, quasi-rectangular slice of less than 0.8 cm wide at an arbitrary position over a 6-cm long sample. The measured T2 distributions are of almost the same quality as regular (bulk) CPMG measurements, with the lower T2 limit being as good as c.a. 0.5 ms. The sequence can be found useful as a supplement or alternative to MRI-based techniques for T2 mapping in short relaxation time samples (water-saturated rocks, building materials, wood, food products, rubbers, etc.), particularly when T2 is required to be measured at only few positions along the sample and the resolution of ˜1 cm is acceptable.

  5. Systematic lossy error protection of video based on H.264/AVC redundant slices

    NASA Astrophysics Data System (ADS)

    Rane, Shantanu; Girod, Bernd

    2006-01-01

    We propose the use of H.264 redundant slices for Systematic Lossy Error Protection (SLEP) of a video signal transmitted over an error-prone channel. In SLEP, the video signal is transmitted to the decoder without channel coding. Additionally, a Wyner-Ziv encoded version of the video signal is transmitted in order to provide error-resilience. In the event of channel errors, the Wyner-Ziv description is decoded as a substitute for the error-prone portions of the primary video signal. Since the Wyner-Ziv description is typically coarser than the primary video signal, SLEP is a lossy error protection technique which trades-off residual quantization distortion for improved error-resilience properties, such as graceful degradation of decoder picture quality. We describe how H.264 redundant slices can be used to generate the Wyner-Ziv description, and present simulation results to demonstrate the advantages of this method over traditional methods such as FEC.

  6. Effect of Experimental Variables of Abrasive Wear on 3D Surface Roughness and Wear Rate of Al-4.5 % Cu Alloy

    NASA Astrophysics Data System (ADS)

    Ghosh, Debashis; Mallik, Manab; Mandal, Nilrudra; Dutta, Samik; Roy, Himadri; Lohar, Aditya Kumar

    2016-05-01

    This investigation was primarily carried out to examine the abrasive wear behavior of as cast Al-4.5 % Cu alloy. Wear tests have been carried out using an abrasive wear machine with emery paper embedded with SiC particles acting as abrasive medium. The experiments were planned using central composite design, with, load, cycle and grit size as input variables, whereas wear rate and 3D roughness were considered as output variable. Analysis of variance was applied to check the adequacy of the mathematical model and their respective parameters. Microstructural investigations of the worn surfaces have been carried out to explain the observed results and to understand the wear micro-mechanisms as per the planned experiments. Desirability function optimization technique was finally employed to optimize the controlling factors. The observed results revealed that, grit size plays a significant role in the variation of wear rate and 3D roughness as compared to load and cycles. Based on the significance of interactions, the regression equations were derived and verified further with a number of confirmation runs to assess the adequacy of the model. A close agreement (±10 %) between the predicted and experimentally measured results was obtained from this investigation.

  7. Fully programmable spectrum sliced chirped microwave photonic filter.

    PubMed

    Leitner, Peter; Yi, Xiaoke; Li, Liwei; Huang, Thomas X H

    2015-02-23

    A novel chirped microwave photonic filter (MPF) capable of achieving a large radio frequency (RF) group delay slope and a single passband response free from high frequency fading is presented. The design is based upon a Fourier domain optical processor (FD-OP) and a single sideband modulator. The FD-OP is utilized to generate both constant time delay to tune the filter and first order dispersion to induce the RF chirp, enabling full software control of the MPF without the need for manual adjustment. An optimized optical parameter region based on a large optical bandwidth >750 GHz and low slicing dispersion < ± 1 ps/nm is introduced, with this technique greatly improving the RF properties including the group delay slope magnitude and passband noise. Experimental results confirm that the structure simultaneously achieves a large in-band RF chirp of -4.2 ns/GHz, centre frequency invariant tuning and independent reconfiguration of the RF amplitude and phase response. Finally, a stochastic study of the device passband noise performance under tuning and reconfiguration is presented, indicating a low passband noise <-120 dB/Hz. PMID:25836442

  8. Effects of irradiation and fumaric acid treatment on the inactivation of Listeria monocytogenes and Salmonella typhimurium inoculated on sliced ham

    NASA Astrophysics Data System (ADS)

    Song, Hyeon-Jeong; Lee, Ji-Hye; Song, Kyung Bin

    2011-11-01

    To examine the effects of fumaric acid and electron beam irradiation on the inactivation of foodborne pathogens in ready-to-eat meat products, sliced ham was inoculated with Listeria monocytogenes and Salmonella typhimurium. The inoculated ham slices were treated with 0.5% fumaric acid or electron beam irradiation at 2 kGy. Fumaric acid treatment reduced the populations of L. monocytogenes and S. typhimurium by approximately 1 log CFU/g compared to control populations. In contrast, electron beam irradiation decreased the populations of S. typhimurium and L. monocytogenes by 3.78 and 2.42 log CFU/g, respectively. These results suggest that electron beam irradiation is a better and appropriate technique for improving the microbial safety of sliced ham.

  9. Graph-based retrospective 4D image construction from free-breathing MRI slice acquisitions

    NASA Astrophysics Data System (ADS)

    Tong, Yubing; Udupa, Jayaram K.; Ciesielski, Krzysztof C.; McDonough, Joseph M.; Mong, Andrew; Campbell, Robert M.

    2014-03-01

    4D or dynamic imaging of the thorax has many potential applications [1, 2]. CT and MRI offer sufficient speed to acquire motion information via 4D imaging. However they have different constraints and requirements. For both modalities both prospective and retrospective respiratory gating and tracking techniques have been developed [3, 4]. For pediatric imaging, x-ray radiation becomes a primary concern and MRI remains as the de facto choice. The pediatric subjects we deal with often suffer from extreme malformations of their chest wall, diaphragm, and/or spine, as such patient cooperation needed by some of the gating and tracking techniques are difficult to realize without causing patient discomfort. Moreover, we are interested in the mechanical function of their thorax in its natural form in tidal breathing. Therefore free-breathing MRI acquisition is the ideal modality of imaging for these patients. In our set up, for each coronal (or sagittal) slice position, slice images are acquired at a rate of about 200-300 ms/slice over several natural breathing cycles. This produces typically several thousands of slices which contain both the anatomic and dynamic information. However, it is not trivial to form a consistent and well defined 4D volume from these data. In this paper, we present a novel graph-based combinatorial optimization solution for constructing the best possible 4D scene from such data entirely in the digital domain. Our proposed method is purely image-based and does not need breath holding or any external surrogates or instruments to record respiratory motion or tidal volume. Both adult and children patients' data are used to illustrate the performance of the proposed method. Experimental results show that the reconstructed 4D scenes are smooth and consistent spatially and temporally, agreeing with known shape and motion of the lungs.

  10. Fabrication and characterization of a new high density Sc/Si multilayer sliced grating

    SciTech Connect

    Advanced Light Source; Voronov, Dmitriy L.; Cambie, Rossana; Gullikson, Eric; Yashchuk, Valeriy; Padmore, Howard; Pershin, Yuri; Ponomarenko, Alexander; Kondratenko, Valeriy

    2008-07-21

    State of the art soft x-ray spectroscopy techniques like Resonant Inelastic X-ray Scattering (RIXS) require diffraction gratings which can provide extremely high spectral resolution of 105-106. This problem may be addressed with a sliced multilayer grating with an ultra-high groove density (up to 50,000 mm-1) proposed in the recent publication [Voronov, D. L., Cambie, R., Feshchenko, R. M., Gullikson, E., Padmore, H. A., Vinogradov, A. V., Yashchuk, V. V., Proc. SPIE 6705, 67050E (2007)]. It has been suggested to fabricate such a grating by deposition of a soft x-ray multilayer on a substrate which is a blazed saw-tooth grating (echellette) with low groove density. Subsequent polishing applied to the coated grating removes part of the coating and forms an oblique-cut multiline structure that is a sliced multilayer grating. The resulting grating has a short-scale periodicity of lines (bilayers), which is defined by the multilayer period and the oblique-cut angle. We fabricated and tested a Sc/Si multilayer sliced grating suitable for EUV applications, which is a first prototype based on the suggested technique. In order to fabricate an echellette substrate, we used anisotropic KOH etching of a Si wafer. The etching regime was optimized to obtain smooth and flat echellette facets. A Sc/Si multilayer was deposited by dc-magnetron sputtering, and after that it was mechanically polished using a number of diamond pastes. The resulting sliced grating prototype with ~;;270 nm line period has demonstrated a dispersive ability in the 41-49 nm photon wavelength range with a diffraction efficiency of ~;;7percent for the optimized 38th order assigned to the echellette grating of 10 mu m period.

  11. Fabrication and characterization of a new high density Sc/Si multilayer sliced grating

    NASA Astrophysics Data System (ADS)

    Voronov, Dmitriy L.; Cambie, Rossana; Gullikson, Eric M.; Yashchuk, Valeriy V.; Padmore, Howard A.; Pershin, Yuri P.; Ponomarenko, Alexander G.; Kondratenko, Valeriy V.

    2008-08-01

    State of the art soft x-ray spectroscopy techniques like Resonant Inelastic X-ray Scattering (RIXS) require diffraction gratings which can provide extremely high spectral resolution of 105-106. This problem may be addressed with a sliced multilayer grating with an ultra-high groove density (up to 50,000 mm-1) proposed in the recent publication [Voronov, D. L., et al., Proc. SPIE 6705, 67050E (2007)]. It has been suggested to fabricate such a grating by deposition of a soft x-ray multilayer on a substrate which is a blazed saw-tooth grating (echellette) with low groove density. Subsequent polishing applied to the coated grating removes part of the coating and forms an oblique-cut multiline structure that is a sliced multilayer grating. The resulting grating has a short-scale periodicity of lines (bilayers), which is defined by the multilayer period and the oblique-cut angle. We fabricated and tested a Sc/Si multilayer sliced grating suitable for EUV applications, which is a first prototype based on the suggested technique. In order to fabricate an echellette substrate, we used anisotropic KOH etching of a Si wafer. The etching regime was optimized to obtain smooth and flat echellette facets. A Sc/Si multilayer was deposited by dc-magnetron sputtering, and after that it was mechanically polished using a number of diamond pastes. The resulting sliced grating prototype with ~270 nm line period has demonstrated a dispersive ability in the 41-49 nm photon wavelength range with a diffraction efficiency of ~7% for the optimized 38th order assigned to the echellette grating of 10 μm period.

  12. A modified technique for fabricating a mirror image wax pattern for an auricular prosthesis.

    PubMed

    Gajdhar, Shaiq; Gajdhar, Sajda Khan; Salakalakonda, Srikanth Reddy; Vasthare, Abubakkar

    2015-01-01

    This article describes a technique for fabricating a wax pattern for an auricular prosthesis by tracing the shape of a sliced cast of the contralateral ear at an interval of 1-mm and transferring the shape of each 1-mm slice to a similar dimension modeling wax sheet. In this way, slices of modeling wax are obtained, which can be reversed and placed over the previous slice to produce a mirror image wax pattern of the contralateral ear. PMID:25277032

  13. Robust Transmission of H.264/AVC Streams Using Adaptive Group Slicing and Unequal Error Protection

    NASA Astrophysics Data System (ADS)

    Thomos, Nikolaos; Argyropoulos, Savvas; Boulgouris, Nikolaos V.; Strintzis, Michael G.

    2006-12-01

    We present a novel scheme for the transmission of H.264/AVC video streams over lossy packet networks. The proposed scheme exploits the error-resilient features of H.264/AVC codec and employs Reed-Solomon codes to protect effectively the streams. A novel technique for adaptive classification of macroblocks into three slice groups is also proposed. The optimal classification of macroblocks and the optimal channel rate allocation are achieved by iterating two interdependent steps. Dynamic programming techniques are used for the channel rate allocation process in order to reduce complexity. Simulations clearly demonstrate the superiority of the proposed method over other recent algorithms for transmission of H.264/AVC streams.

  14. Communication: Time- and space-sliced velocity map electron imaging

    SciTech Connect

    Lee, Suk Kyoung; Lin, Yun Fei; Lingenfelter, Steven; Fan, Lin; Winney, Alexander H.; Li, Wen

    2014-12-14

    We develop a new method to achieve slice electron imaging using a conventional velocity map imaging apparatus with two additional components: a fast frame complementary metal-oxide semiconductor camera and a high-speed digitizer. The setup was previously shown to be capable of 3D detection and coincidence measurements of ions. Here, we show that when this method is applied to electron imaging, a time slice of 32 ps and a spatial slice of less than 1 mm thick can be achieved. Each slice directly extracts 3D velocity distributions of electrons and provides electron velocity distributions that are impossible or difficult to obtain with a standard 2D imaging electron detector.

  15. Computed tomographic coronary angiography: how many slices do you need?

    PubMed Central

    Peebles, C

    2006-01-01

    While increasing the number of slices in multislice computed tomography clearly brings benefits in terms of detecting significant coronary disease, heavy calcification remains a problem, as does the high radiation burden PMID:16614268

  16. The Mars Environmental Compatibility Assessment (MECA) Abrasion Tool

    NASA Technical Reports Server (NTRS)

    Kuhlman, K. R.; Anderson, M. S.; Hinde, B. D.; Hecht, M. H.; Pike, W. T.; Marshall, J. R.; Meloy, T. P.

    1999-01-01

    The Mars Environmental Compatibility Assessment (MECA) experiment, an instrument suite to be flown on Mars Surveyor 2001, will include a tool for doing simple mineralogical scratch and streak tests on particles from the Martian regolith. The Abrasion Tool will be applied to particles that adhere themselves to highly polished substrates of various hardnesses. Granular soil components will be subjected to a compressive force of about 3 N using a leaf spring. The spring will be applied with a paraffin actuator capable of a 0.76 mm throw to achieve a maximum displacement of about 7.5 mm at the tip of the tool. The pressure per grain will be dependent on the grain size, the number of grains that adhere to the substrate and the number of grains in compression. The pressure per particle is expected to be on the order of 100 MPa - 1 GPa. The MECA sample wheel containing the substrates will be rotated after the particles are placed in compression to produce scratches or pits. A primary goal of the Abrasion Tool is to identify quartz (Mohs' hardness = 7) using substrates of varying hardnesses. Quartz is considered hazardous to future human explorers of Mars because it can cause silicosis of the lungs if it is of respirable size. It is also hazardous to machinery, structures, and space suits because of its ability to abrade and scratch surfaces. Since large quantities of minerals harder than quartz are not expected, any scratches produced on polished quartz substrates might be reasonably attributed to quartz particles, although there may be minerals such as impact metamorphic diamond in the soils. Careful calibration of the tool will be necessary to ensure that grains are not overloaded; for example, a steel ball pressed into glass will produce a Hertzian fracture, even though it is softer than glass. Other minerals, such as magnetite (Mohs' hardness = 6.5) have been shown to scratch glass ceramics such as Zerodur (Mohs' hardness = 6.5). Thus, minerals can be differentiated

  17. The Mars Environmental Compatibility Assessment MECA Abrasion Tool

    NASA Astrophysics Data System (ADS)

    Kuhlman, K. R.; Anderson, M. S.; Hinde, B. D.; Hecht, M. H.; Pike, W. T.; Marshall, J.; Meloy, T. P.; Cobbly, T.

    1999-09-01

    The Mars Environmental Compatibility Assessment (MECA) experiment, an instrument suite to be flown on Mars Surveyor 2001, will include a tool for doing simple mineralogical scratch and streak tests on particles from the Martian regolith. The Abrasion Tool will be applied to particles that adhere to highly polished substrates of various hardnesses. Granular soil components will be subjected to a compressive force of about 3 N using a leaf spring. The spring will be applied with a paraffin actuator capable of a 0.76 mm throw to achieve a maximum displacement of about 7.5 mm at the tip of the tool. The pressure per grain will be dependent on the grain size, the number of grains that adhere to the substrate and the number of grains in compression. The pressure per particle is expected to be on the order of 100 MPa - 1 GPa. The MECA sample wheel containing the substrates will be rotated after the particles are placed in compression to produce scratches or pits. A primary goal of the Abrasion Tool is to identify quartz (Mohs' hardness = 7) using substrates of varying hardnesses. Quartz is considered hazardous to future human explorers of Mars because it can cause silicosis of the lungs if it is of respirable size. It is also hazardous to machinery, structures, and space suits because of its ability to abrade and scratch surfaces. Since large quantities of minerals harder than quartz are not expected, any scratches produced on polished quartz substrates might be reasonably attributed to quartz particles, although there may be minerals such as impact metamorphic diamond in the soils. Careful calibration of the tool will be necessary to ensure that grains are not overloaded; for example, a steel ball pressed into glass will produce a Hertzian fracture, even though it is softer than glass. Other minerals, such as magnetite (Mohs'hardness = 6.5) have been shown to scratch glass ceramics such as Zerodur (Mohs' hardness = 6.5). Thus, minerals can be differentiated: note that

  18. The Mars Environmental Compatibility Assessment MECA Abrasion Tool

    NASA Technical Reports Server (NTRS)

    Kuhlman, K. R.; Anderson, M. S.; Hinde, B. D.; Hecht, M. H.; Pike, W. T.; Marshall, J.; Meloy, T. P.; Cobbly, T.

    1999-01-01

    The Mars Environmental Compatibility Assessment (MECA) experiment, an instrument suite to be flown on Mars Surveyor 2001, will include a tool for doing simple mineralogical scratch and streak tests on particles from the Martian regolith. The Abrasion Tool will be applied to particles that adhere to highly polished substrates of various hardnesses. Granular soil components will be subjected to a compressive force of about 3 N using a leaf spring. The spring will be applied with a paraffin actuator capable of a 0.76 mm throw to achieve a maximum displacement of about 7.5 mm at the tip of the tool. The pressure per grain will be dependent on the grain size, the number of grains that adhere to the substrate and the number of grains in compression. The pressure per particle is expected to be on the order of 100 MPa - 1 GPa. The MECA sample wheel containing the substrates will be rotated after the particles are placed in compression to produce scratches or pits. A primary goal of the Abrasion Tool is to identify quartz (Mohs' hardness = 7) using substrates of varying hardnesses. Quartz is considered hazardous to future human explorers of Mars because it can cause silicosis of the lungs if it is of respirable size. It is also hazardous to machinery, structures, and space suits because of its ability to abrade and scratch surfaces. Since large quantities of minerals harder than quartz are not expected, any scratches produced on polished quartz substrates might be reasonably attributed to quartz particles, although there may be minerals such as impact metamorphic diamond in the soils. Careful calibration of the tool will be necessary to ensure that grains are not overloaded; for example, a steel ball pressed into glass will produce a Hertzian fracture, even though it is softer than glass. Other minerals, such as magnetite (Mohs'hardness = 6.5) have been shown to scratch glass ceramics such as Zerodur (Mohs' hardness = 6.5). Thus, minerals can be differentiated: note that

  19. Inter-slice bidirectional registration-based segmentation of the prostate gland in MR and CT image sequences

    SciTech Connect

    Khalvati, Farzad Tizhoosh, Hamid R.; Salmanpour, Aryan; Rahnamayan, Shahryar; Rodrigues, George

    2013-12-15

    Purpose: Accurate segmentation and volume estimation of the prostate gland in magnetic resonance (MR) and computed tomography (CT) images are necessary steps in diagnosis, treatment, and monitoring of prostate cancer. This paper presents an algorithm for the prostate gland volume estimation based on the semiautomated segmentation of individual slices in T2-weighted MR and CT image sequences. Methods: The proposedInter-Slice Bidirectional Registration-based Segmentation (iBRS) algorithm relies on interslice image registration of volume data to segment the prostate gland without the use of an anatomical atlas. It requires the user to mark only three slices in a given volume dataset, i.e., the first, middle, and last slices. Next, the proposed algorithm uses a registration algorithm to autosegment the remaining slices. We conducted comprehensive experiments to measure the performance of the proposed algorithm using three registration methods (i.e., rigid, affine, and nonrigid techniques). Results: The results with the proposed technique were compared with manual marking using prostate MR and CT images from 117 patients. Manual marking was performed by an expert user for all 117 patients. The median accuracies for individual slices measured using the Dice similarity coefficient (DSC) were 92% and 91% for MR and CT images, respectively. The iBRS algorithm was also evaluated regarding user variability, which confirmed that the algorithm was robust to interuser variability when marking the prostate gland. Conclusions: The proposed algorithm exploits the interslice data redundancy of the images in a volume dataset of MR and CT images and eliminates the need for an atlas, minimizing the computational cost while producing highly accurate results which are robust to interuser variability.

  20. A Unified Approach to Diffusion Direction Sensitive Slice Registration and 3-D DTI Reconstruction From Moving Fetal Brain Anatomy

    PubMed Central

    Fogtmann, Mads; Seshamani, Sharmishtaa; Kroenke, Christopher; Cheng, Xi; Chapman, Teresa; Wilm, Jakob; Rousseau, François

    2014-01-01

    This paper presents an approach to 3-D diffusion tensor image (DTI) reconstruction from multi-slice diffusion weighted (DW) magnetic resonance imaging acquisitions of the moving fetal brain. Motion scatters the slice measurements in the spatial and spherical diffusion domain with respect to the underlying anatomy. Previous image registration techniques have been described to estimate the between slice fetal head motion, allowing the reconstruction of 3-D a diffusion estimate on a regular grid using interpolation. We propose Approach to Unified Diffusion Sensitive Slice Alignment and Reconstruction (AUDiSSAR) that explicitly formulates a process for diffusion direction sensitive DW-slice-to-DTI-volume alignment. This also incorporates image resolution modeling to iteratively deconvolve the effects of the imaging point spread function using the multiple views provided by thick slices acquired in different anatomical planes. The algorithm is implemented using a multi-resolution iterative scheme and multiple real and synthetic data are used to evaluate the performance of the technique. An accuracy experiment using synthetically created motion data of an adult head and a experiment using synthetic motion added to sedated fetal monkey dataset show a significant improvement in motion-trajectory estimation compared to a state-of-the-art approaches. The performance of the method is then evaluated on challenging but clinically typical in utero fetal scans of four different human cases, showing improved rendition of cortical anatomy and extraction of white matter tracts. While the experimental work focuses on DTI reconstruction (second-order tensor model), the proposed reconstruction framework can employ any 5-D diffusion volume model that can be represented by the spatial parameterizations of an orientation distribution function. PMID:24108711

  1. Fluvial erosion of physically modeled abrasion-dominated slot canyons

    NASA Astrophysics Data System (ADS)

    Carter, Carissa L.; Anderson, Robert S.

    2006-11-01

    Abrasion-dominated fluvial erosion generates slot canyons in massive bedrock with intricately undulating walls. Flows in slot canyons are unusual in that the walls comprise a significant portion of the wetted perimeter of the flow during geomorphically effective floods. In Wire Pass, Utah, the upper Paria River incises through massive, crossbedded Navajo Sandstone. Incision in Wire Pass and related slots occurs only during flash floods; paleoflood debris indicates that the width/depth ratios of these flows are at times as low as 1:1. Submeter resolution field mapping of a 20-m length of Wire Pass shows that the wall morphology is a complicated combination of in-phase (meander-like) and out-of-phase (pinch and swell) undulations. In order to investigate evolution of slot canyons and the influence of their wall shapes on flow dynamics, we recorded the evolution of four distinct canyon wall morphologies in a 2.4 m flume box at the St. Anthony Falls Laboratory. In a substrate consisting of ˜ 3:2 mixtures of F110 sand and Plaster of Paris, we molded canyons with in-phase and out-of-phase undulations, and wide (6.5 cm) and narrow (4 cm) straight initial wall profiles. Discharges ranged from 1.4 L/s to 2.9 L/s, and wall and bed morphology were measured at 5 h intervals at 0.5 cm resolution. Results show efficient back-eddy erosion in the undulating canyon walls and related erosional bedforms in all channels created by vortices in the flow. Maximum filaments of velocity are depressed and asymmetric, and the implied shear stress distribution varied in space and time on the channel beds. Flow width/depth ratios strongly influence the flow structure and distribution of shear stress in a slot and appear to be a factor in dictating whether a bedrock channel widens its walls or incises its bed.

  2. Hydro- abrasive jet machining modeling for computer control and optimization

    NASA Astrophysics Data System (ADS)

    Groppetti, R.; Jovane, F.

    1993-06-01

    Use of hydro-abrasive jet machining (HAJM) for machining a wide variety of materials—metals, poly-mers, ceramics, fiber-reinforced composites, metal-matrix composites, and bonded or hybridized mate-rials—primarily for two- and three-dimensional cutting and also for drilling, turning, milling, and deburring, has been reported. However, the potential of this innovative process has not been explored fully. This article discusses process control, integration, and optimization of HAJM to establish a plat-form for the implementation of real-time adaptive control constraint (ACC), adaptive control optimiza-tion (ACO), and CAD/CAM integration. It presents the approach followed and the main results obtained during the development, implementation, automation, and integration of a HAJM cell and its computer-ized controller. After a critical analysis of the process variables and models reported in the literature to identify process variables and to define a process model suitable for HAJM real-time control and optimi-zation, to correlate process variables and parameters with machining results, and to avoid expensive and time-consuming experiments for determination of the optimal machining conditions, a process predic-tion and optimization model was identified and implemented. Then, the configuration of the HAJM cell, architecture, and multiprogramming operation of the controller in terms of monitoring, control, process result prediction, and process condition optimization were analyzed. This prediction and optimization model for selection of optimal machining conditions using multi-objective programming was analyzed. Based on the definition of an economy function and a productivity function, with suitable constraints relevant to required machining quality, required kerfing depth, and available resources, the model was applied to test cases based on experimental results.

  3. Using frictional power to model LSST removal with conventional abrasives

    NASA Astrophysics Data System (ADS)

    Allen, Richard G.; Hubler, William H.

    2015-08-01

    The stressed lap on the Large Polishing Machine (LPM) at the University of Arizona Richard F. Caris Mirror Lab has recently been used to polish the M1 and M3 surfaces of the 8.4-m mirror for the Large Synoptic Survey Telescope (LSST). Loadcells in the three 4-bar links that connect this lap to the spindle of the machine allow the translational forces and torque on the lap to be measured once a second. These force readings and all other available machine parameters are recorded in history files that can be used to create a 2D removal map from one or more polishing runs. While the Preston equation has been used for many years to predict removal in a conventional polishing process, we have adopted a new equation that assumes that removal is proportional to the energy that is transferred from the lap to the substrate via friction. Specifically, the instantaneous removal rate at any point is defined to be the product of four parameters - an energy conversion factor which we call the Allen coefficient, the coefficient of friction, the lap pressure, and the speed of the lap. The Allen coefficient is the ratio of volumetric removal to frictional energy for a particular combination of pad material, abrasive, and substrate. Because our calculations take into account changes in the coefficient of friction between the lap and mirror, our 2D removal maps usually correlate well with optical data. Removal maps for future polishing strokes are created in simulations that track the position and speed of individual lap pads.

  4. Cardiac tissue slices: preparation, handling, and successful optical mapping.

    PubMed

    Wang, Ken; Lee, Peter; Mirams, Gary R; Sarathchandra, Padmini; Borg, Thomas K; Gavaghan, David J; Kohl, Peter; Bollensdorff, Christian

    2015-05-01

    Cardiac tissue slices are becoming increasingly popular as a model system for cardiac electrophysiology and pharmacology research and development. Here, we describe in detail the preparation, handling, and optical mapping of transmembrane potential and intracellular free calcium concentration transients (CaT) in ventricular tissue slices from guinea pigs and rabbits. Slices cut in the epicardium-tangential plane contained well-aligned in-slice myocardial cell strands ("fibers") in subepicardial and midmyocardial sections. Cut with a high-precision slow-advancing microtome at a thickness of 350 to 400 μm, tissue slices preserved essential action potential (AP) properties of the precutting Langendorff-perfused heart. We identified the need for a postcutting recovery period of 36 min (guinea pig) and 63 min (rabbit) to reach 97.5% of final steady-state values for AP duration (APD) (identified by exponential fitting). There was no significant difference between the postcutting recovery dynamics in slices obtained using 2,3-butanedione 2-monoxime or blebistatin as electromechanical uncouplers during the cutting process. A rapid increase in APD, seen after cutting, was caused by exposure to ice-cold solution during the slicing procedure, not by tissue injury, differences in uncouplers, or pH-buffers (bicarbonate; HEPES). To characterize intrinsic patterns of CaT, AP, and conduction, a combination of multipoint and field stimulation should be used to avoid misinterpretation based on source-sink effects. In summary, we describe in detail the preparation, mapping, and data analysis approaches for reproducible cardiac tissue slice-based investigations into AP and CaT dynamics. PMID:25595366

  5. Eight-Bit-Slice GaAs General Processor Circuit

    NASA Technical Reports Server (NTRS)

    Weissman, John; Gauthier, Robert V.

    1989-01-01

    Novel GaAs 8-bit slice enables quick and efficient implementation of variety of fast GaAs digital systems ranging from central processing units of computers to special-purpose processors for communications and signal-processing applications. With GaAs 8-bit slice, designers quickly configure and test hearts of many digital systems that demand fast complex arithmetic, fast and sufficient register storage, efficient multiplexing and routing of data words, and ease of control.

  6. Multiple-bipolar-tap tunable spectrum sliced microwave photonic filter.

    PubMed

    Chen, Tong; Yi, Xiaoke; Huang, Thomas; Minasian, Robert A

    2010-12-01

    A spectrum sliced microwave photonic signal processor structure, which is all-fiber based and features simplicity, together with the ability to realize tunability, reconfigurability, bipolar taps, and multiple-tap rf filtering, is presented. It is based on thermally controlled optical slicing filters induced into two linearly chirped fiber Bragg gratings. Experimental results demonstrate the realization of versatile microwave photonic filters with frequency tunable, reconfiguration, and bipolar-tap generation capabilities. PMID:21124570

  7. PRECISION-CUT SLICE CULTURE METHOD FOR RAT PLACENTA

    PubMed Central

    Gilligan, Jeffrey; Tong, Ming; Longato, Lisa; de la Monte, Suzanne M; Gundogan, Fusun

    2011-01-01

    Primary trophoblasts, placental explants, and cell line cultures are commonly used to investigate placental development, physiology, and pathology, particularly in relation to pregnancy outcomes. Organotypic slice cultures are increasingly used in other systems because they maintain the normal three-dimensional tissue architecture and have all cell types represented. Herein, we demonstrate the utility of the precision-cut placental slice culture model for studying trophoblastic diseases. PMID:22079834

  8. Cardiac tissue slices: preparation, handling, and successful optical mapping

    PubMed Central

    Wang, Ken; Lee, Peter; Mirams, Gary R.; Sarathchandra, Padmini; Borg, Thomas K.; Gavaghan, David J.; Kohl, Peter

    2015-01-01

    Cardiac tissue slices are becoming increasingly popular as a model system for cardiac electrophysiology and pharmacology research and development. Here, we describe in detail the preparation, handling, and optical mapping of transmembrane potential and intracellular free calcium concentration transients (CaT) in ventricular tissue slices from guinea pigs and rabbits. Slices cut in the epicardium-tangential plane contained well-aligned in-slice myocardial cell strands (“fibers”) in subepicardial and midmyocardial sections. Cut with a high-precision slow-advancing microtome at a thickness of 350 to 400 μm, tissue slices preserved essential action potential (AP) properties of the precutting Langendorff-perfused heart. We identified the need for a postcutting recovery period of 36 min (guinea pig) and 63 min (rabbit) to reach 97.5% of final steady-state values for AP duration (APD) (identified by exponential fitting). There was no significant difference between the postcutting recovery dynamics in slices obtained using 2,3-butanedione 2-monoxime or blebistatin as electromechanical uncouplers during the cutting process. A rapid increase in APD, seen after cutting, was caused by exposure to ice-cold solution during the slicing procedure, not by tissue injury, differences in uncouplers, or pH-buffers (bicarbonate; HEPES). To characterize intrinsic patterns of CaT, AP, and conduction, a combination of multipoint and field stimulation should be used to avoid misinterpretation based on source-sink effects. In summary, we describe in detail the preparation, mapping, and data analysis approaches for reproducible cardiac tissue slice-based investigations into AP and CaT dynamics. PMID:25595366

  9. Combined infrared-vacuum drying of pumpkin slices.

    PubMed

    Ghaboos, Seyyed Hossein Hosseini; Ardabili, Seyed Mahdi Seyedain; Kashaninejad, Mahdi; Asadi, Gholamhassan; Aalami, Mehran

    2016-05-01

    Infrared-vacuum dehydration characteristics of pumpkin (Cucurbita moschata) were evaluated in a combined dryer system. The effects of drying parameters, infrared radiation power (204-272 W), system pressure (5-15 kPa), slice thickness (5 and 7 mm) and time (0-220 min) on the drying kinetics and characteristics of pumpkin slices were investigated. The vacuum pressure, lamp power and slice had significant effect on the drying kinetics and various qualities of the dried pumpkin. Moisture ratios were fitted to 10 different mathematical equations using nonlinear regression analysis. The quadratic equation satisfactorily described the drying behavior of pumpkin slices with the highest r value and the lowest SE values. The effective moisture diffusivity increased with power and ranged between 0.71 and 2.86 × 10(-9) m(2)/s. With increasing in infrared radiation power from 204 to 272 W, β-carotene content of dried pumpkins decreased from 30.04 to 24.55 mg/100 g. The rise in infrared power has a negative effect on the color changes (ΔE). The optimum condition was determined as power, 238W, pressure, 5 kPa and slice thickness, 5mm. These conditions resulted into dried pumpkin slices with maximum B-carotene retention. PMID:27407204

  10. Preservation of low slice emittance in bunch compressors

    NASA Astrophysics Data System (ADS)

    Bettoni, S.; Aiba, M.; Beutner, B.; Pedrozzi, M.; Prat, E.; Reiche, S.; Schietinger, T.

    2016-03-01

    Minimizing the dilution of the electron beam emittance is crucial for the performance of accelerators, in particular for free electron laser facilities, where the length of the machine and the efficiency of the lasing process depend on it. Measurements performed at the SwissFEL Injector Test Facility revealed an increase in slice emittance after compressing the bunch even for moderate compression factors. The phenomenon was experimentally studied by characterizing the dependence of the effect on beam and machine parameters relevant for the bunch compression. The reproduction of these measurements in simulation required the use of a 3D beam dynamics model along the bunch compressor that includes coherent synchrotron radiation. Our investigations identified transverse effects, such as coherent synchrotron radiation and transverse space charge as the sources of the observed emittance dilution, excluding other effects, such as chromatic effects on single slices or spurious dispersion. We also present studies, both experimental and simulation based, on the effect of the optics mismatch of the slices on the variation of the slice emittance along the bunch. After a corresponding reoptimization of the beam optics in the test facility we reached slice emittances below 200 nm for the central slices along the longitudinal dimension with a moderate increase up to 300 nm in the head and tail for a compression factor of 7.5 and a bunch charge of 200 pC, equivalent to a final current of 150 A, at about 230 MeV energy.

  11. Videomicroscopy of methacholine-induced contraction of individual airways in precision-cut lung slices.

    PubMed

    Martin, C; Uhlig, S; Ullrich, V

    1996-12-01

    Contraction of airways of different size can be studied in viable lung slices by videomicroscopy. However, at present, application of this technique is limited by the heterogeneous responses obtained. We investigated the use of precision-cut lung slices to examine contraction of individual airways. Lung slices of 250 +/- 20 microns were prepared from Wistar rats and cultured in a roller incubator in serum-free minimum essential medium (MEM). Under these conditions, the slices were viable for at least 70 h, as indicated by leakage of lactate dehydrogenase into the supernatant, thymidine incorporation and ciliary beating. The slices were placed in a newly developed incubation chamber and mounted by a nylon thread that was fixed to a platinum wire. The whole chamber was positioned on a microscope stage, and contraction of single airways was followed under a microscope that was coupled to a CCD-camera. Reduction in airway area was taken as an index of bronchoconstriction and was determined by a computer program. Addition of methacholine resulted in a concentration-dependent (concentration producing half the maximal effect (EC50) = 0.64 +/- 0.08 (mean +/- SD) microM; n = 64) contraction of single airways. In the presence of hydrocortisone, the EC50 was about six times greater, i.e. 3.7 +/- 0.9 microM (n = 7), and the effect of the steroid was largely abolished by propanolol (EC50 = 1.1 +/- 0.1 microM; n = 7). Airways with an area smaller than 35,000 microns2 were nearly nine times more sensitive to methacholine (EC50 = 0.1 +/- 0.03 microM; n = 20) than larger ones (EC50 = 87 +/- 0.27 microM; n = 22). We conclude that cultured precision-cut lung slices are a useful model for routine study of contraction of individual airways of various sizes. The measurements were precise and reproducible and showed that smaller airways are more sensitive to methacholine than larger ones. PMID:8980957

  12. Evaluation of slice shear force as an objective method of assessing beef longissimus tenderness.

    PubMed

    Shackelford, S D; Wheeler, T L; Koohmaraie, M

    1999-10-01

    Experiments were conducted to develop an optimal protocol for measurement of slice shear force (SSF) and to evaluate SSF as an objective method of assessing beef longissimus tenderness. Whereas six cylindrical, 1.27-cm-diameter cores are typically removed from each steak for Warner-Bratzler shear force (WBSF) determination, a single 1-cm-thick, 5-cm-long slice is removed from the lateral end of each longissimus steak for SSF. For either technique, samples are removed parallel to the muscle fiber orientation and sheared across the fibers. Whereas WBSF uses a V-shaped blade, SSF uses a flat blade with the same thickness (1.016 mm) and degree of bevel (half-round) on the shearing edge. In Exp. 1, longissimus steaks were acquired from 60 beef carcasses to determine the effects of belt grill cooking rate (very rapid vs. rapid) and conditions of SSF measurement (hot vs cold) on the relationship of SSF with trained sensory panel (TSP) tenderness rating. Slice shear force was more strongly correlated with TSP tenderness rating when SSF measurement was conducted immediately after cooking (r = -.74 to -.76) than when steaks were chilled (24 h, 4 degrees C) before SSF measurement (r = -.57 to -.72). When SSF measurement was conducted immediately after cooking, the relationship of SSF with TSP tenderness rating did not differ among the belt grill cooking protocols used to cook the SSF steak. In Exp. 2, longissimus steaks were acquired from 479 beef carcasses to compare the ability of SSF and WBSF of 1.27-cm-diameter cores to predict TSP tenderness ratings. Slice shear force was more strongly correlated with sensory panel tenderness rating than was WBSF (r = -.82 vs -.77). In Exp. 3, longissimus steaks were acquired from 110 beef carcasses to evaluate the repeatability (.91) of SSF over a broad range of tenderness. Slice shear force is a more rapid, more accurate, and technically less difficult technique than WBSF. Use of the SSF technique could facilitate the collection of

  13. Combined effect of end-rounded versus tapered bristles and a dentifrice on plaque removal and gingival abrasion.

    PubMed

    Caporossi, Leonardo Stephan; Dutra, Danilo Antonio Milbradt; Martins, Maritieli Righi; Prochnow, Emilia Pithan; Moreira, Carlos Heitor Cunha; Kantorski, Karla Zanini

    2016-01-01

    Two previous clinical studies evaluated the effect of end-rounded versus tapered bristles of soft manual brushes on the removal of plaque and gingival abrasion. However, the combined effect of an abrasive dentifrice on these outcomes has yet to be understood. The purpose of the present study was to compare the incidence of gingival abrasion and the degree of plaque removal obtained after the use of toothbrushes with tapered or end-rounded bristles in the presence or absence of an abrasive dentifrice. The study involved a randomized, single-blind, crossover model (n = 39) with a split-mouth design. Subjects were instructed to refrain from performing oral hygiene procedures for 72 hours. Quadrants were randomized and subjects brushed with both types of toothbrushes using a dentifrice (relative dentin abrasion = ± 160). Plaque and gingival abrasion were assessed before and after brushing. After 7 days, the experiment was repeated without the dentifrice. The average reduction in plaque scores and the average increase in the number of abrasion sites were assessed by repeated-measures ANOVA and Bonferroni's post-hoc tests. End-rounded bristles removed significantly more plaque than tapered bristles, regardless of the use of a dentifrice. The dentifrice did not improve plaque removal. In the marginal area (cervical free gingiva), no difference in the incidence of gingival abrasion was detected between toothbrush types when used with a dentifrice (p ≥ 0.05). However, the dentifrice increased the incidence of abrasion (p < 0.001), irrespective of the toothbrush type tested. End-rounded bristles therefore removed plaque more effectively without causing a higher incidence of gingival abrasion when compared with tapered bristles. An abrasive dentifrice can increase the incidence of abrasion, and should be used with caution by individuals who are at risk of developing gingival recession. PMID:26981758

  14. Failure of a novel silicone–polyurethane copolymer (Optim™) to prevent implantable cardioverter-defibrillator lead insulation abrasions

    PubMed Central

    Hauser, Robert G.; Abdelhadi, Raed H.; McGriff, Deepa M.; Kallinen Retel, Linda

    2013-01-01

    Aim The purpose of this study was to determine if Optim™, a unique copolymer of silicone and polyurethane, protects Riata ST Optim and Durata implantable cardioverter-defibrillator (ICD) leads (SJM, St Jude Medical Inc., Sylmar, CA, USA) from abrasions that cause lead failure. Methods and results We searched the US Food and Drug Administration's (FDA's) Manufacturers and User Device Experience (MAUDE) database on 13 April 2012 using the simple search terms ‘Riata ST Optim™ abrasion analysis’ and ‘Durata abrasion analysis’. Lead implant time was estimated by subtracting 3 months from the reported lead age. The MAUDE search returned 15 reports for Riata ST Optim™ and 37 reports for Durata leads, which were submitted by SJM based on its analyses of returned leads for clinical events that occurred between December 2007 and January 2012. Riata ST Optim™ leads had been implanted 29.1 ± 11.7 months. Eight of 15 leads had can abrasions and three abrasions were caused by friction with another device, most likely another lead. Four of these abrasions resulted in high-voltage failures and one death. One failure was caused by an internal insulation defect. Durata leads had been implanted 22.2 ± 10.6 months. Twelve Durata leads had can abrasions, and six leads had abrasions caused by friction with another device. Of these 18 can and other device abrasions, 13 (72%) had electrical abnormalities. Low impedances identified three internal insulation abrasions. Conclusions Riata ST Optim™ and Durata ICD leads have failed due to insulation abrasions. Optim™ did not prevent these abrasions, which developed ≤4 years after implant. Studies are needed to determine the incidence of these failures and their clinical implications. PMID:22915789

  15. Use of single-slice thick slab phase-contrast angiography for the diagnosis of dural venous sinus thrombosis.

    PubMed

    Adams, W M; Laitt, R D; Beards, S C; Kassner, A; Jackson, A

    1999-01-01

    The aim of this study was to examine the reliability of single-slice phase-contrast angiography (SSPCA) as a rapid technique for the investigation of suspected dural venous sinus occlusion. Images were obtained on 25 normal volunteers to document the accuracy of SSPCA in the demonstration of slow flow states. Normal volunteers were imaged using sagittal and coronal SSPCA (slice thickness 13 cm, matrix 256 x 256, TR 14 ms, TE 7 ms, flip angle 20 degrees, peak velocity encoding rate 30 cm/s). Sinus patency and flow rate were confirmed by measurement of flow in the superior sagittal and transverse sinuses using quantified single-slice phase difference images. Imaging was performed in 50 patients undergoing routine brain scans in order to determine the optimal slice orientation for clinical use. Twenty-one patients with suspected dural venous sinus thrombosis were also investigated with SSPCA and the diagnosis confirmed by one or more alternative imaging techniques. Imaging time was 29 s per acquisition and image quality was good in all cases. Variations in dural sinus patency and flow in normal volunteers were accurately predicted by SSPCA (kappa = 0.92). Use of a single angulated slice (130 mm thick, para-sagittal image angled 30 degrees towards coronal and 30 degrees towards transverse) provided sufficient separation of right- and left-sided venous structures to allow use of a single projection. The presence and extent of sinus occlusions in 14 patients and the absence of thrombosis in 7 were accurately identified by SSPCA. Sensitivity and specificity in this limited study were both 100%. The SSPCA technique takes less than 30 s and provides a reliable and rapid technique for the diagnosis of dural venous sinus thrombosis. PMID:10525876

  16. Interspecific hybridization between Tigridia pavonia and T. augusta through ovary slice culture.

    PubMed

    Piña-Escutia, J-L; Vázquez-García, L-M; Arzate-Fernández, A-M

    2013-01-01

    Tigridia pavonia is the most popular species in the Tigridia genus, and is currently marketed in Europe, Asia, and Australia as a landscape plant. Although it is native to Mexico, there are no breeding programs for it. In this study, we attempted to increase its flower color spectrum and growth habit by interspecific hybridization with T. augusta. Interspecific hybrids between T. pavonia and T. augusta were successfully obtained for the first time using the cut-style pollination and ovary slice culture techniques. On the contrary, no hybrids were obtained from a reciprocal cross. At three, four, and five days after pollination (DAP) ovaries were sliced and cultured on Murashige and Skoog medium without growth regulators and ammonium nitrate, but were supplemented with 6% sucrose, 50 mg/L yeast extract, and 0.25% Gelrite. After 80 days of culture initiation, the germination of only 10 embryos was observed in ovary slices cultured at three DAP. After transfer to identical fresh medium, six hybrid embryos developed into seedlings. All obtained hybrid seedlings were transplanted successfully to soil, and grew normally. The progenies investigated were identified as true hybrids based on randomly amplified polymorphic DNA analysis. PMID:23359019

  17. A novel electrochemical approach for prolonged measurement of absolute levels of extracellular dopamine in brain slices.

    PubMed

    Burrell, Mark H; Atcherley, Christopher W; Heien, Michael L; Lipski, Janusz

    2015-11-18

    Tonic dopamine (DA) levels influence the activity of dopaminergic neurons and the dynamics of fast dopaminergic transmission. Although carbon fiber microelectrodes and fast-scan cyclic voltammetry (FSCV) have been extensively used to quantify stimulus-induced release and uptake of DA in vivo and in vitro, this technique relies on background subtraction and thus cannot provide information about absolute extracellular concentrations. It is also generally not suitable for prolonged (>90 s) recordings due to drift of the background current. A recently reported, modified FSCV approach called fast-scan controlled-adsorption voltammetry (FSCAV) has been used to assess tonic DA levels in solution and in the anesthetized mouse brain. Here we describe a novel extension of FSCAV to investigate pharmacologically induced, slowly occurring changes in tonic (background) extracellular DA concentration, and phasic (stimulated) DA release in brain slices. FSCAV was used to measure adsorption dynamics and changes in DA concentration (for up to 1.5 h, sampling interval 30 s, detection threshold < 10 nM) evoked by drugs affecting DA release and uptake (amphetamine, l-DOPA, pargyline, cocaine, Ro4-1284) in submerged striatal slices obtained from rats. We also show that combined FSCAV-FSCV recordings can be used for concurrent study of stimulated release and changes in tonic DA concentration. Our results demonstrate that FSCAV can be effectively used in brain slices to measure prolonged changes in extracellular level of endogenous DA expressed as absolute values, complementing studies conducted in vivo with microdialysis. PMID:26322962

  18. Supervised neural network classification of pre-sliced cooked pork ham images using quaternionic singular values.

    PubMed

    Valous, Nektarios A; Mendoza, Fernando; Sun, Da-Wen; Allen, Paul

    2010-03-01

    The quaternionic singular value decomposition is a technique to decompose a quaternion matrix (representation of a colour image) into quaternion singular vector and singular value component matrices exposing useful properties. The objective of this study was to use a small portion of uncorrelated singular values, as robust features for the classification of sliced pork ham images, using a supervised artificial neural network classifier. Images were acquired from four qualities of sliced cooked pork ham typically consumed in Ireland (90 slices per quality), having similar appearances. Mahalanobis distances and Pearson product moment correlations were used for feature selection. Six highly discriminating features were used as input to train the neural network. An adaptive feedforward multilayer perceptron classifier was employed to obtain a suitable mapping from the input dataset. The overall correct classification performance for the training, validation and test set were 90.3%, 94.4%, and 86.1%, respectively. The results confirm that the classification performance was satisfactory. Extracting the most informative features led to the recognition of a set of different but visually quite similar textural patterns based on quaternionic singular values. PMID:20374805

  19. Elemental analysis of renal slices by proton-induced X-ray emission.

    PubMed Central

    Lowe, T; Chen, Q; Fernando, Q; Keith, R; Gandolfi, A J

    1993-01-01

    We optimized proton-induced X-ray emission (PIXE) for tissue analysis in a toxicity-disposition study. We used cultured rabbit renal slices as the biological system to demonstrate the use of PIXE analysis. The renal slices were exposed to HgCl2, CdCl2, K2Cr2O7, or NaAsO2 alone or in a mixture. The PIXE analysis provides information on concentrations of elements above atomic number 11, and it is the only analytical technique that can determine 20-30 elements nondestructively in a single, small sample (approximately 5 mg) with detection limits of 1-5 ppm (dry weight). The renal slices are thin targets that yield X-ray emission spectra with low backgrounds and high elemental sensitivities. The nondestructive nature of PIXE and the ability to simultaneously measure uptake of multiple metals and endogenous elements are unique to this methodology. Images p302-a Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. A Figure 6. B Figure 6. C Figure 6. D Figure 7. A Figure 7. B Figure 7. C Figure 7. D p307-a PMID:8275986

  20. Patch-clamp recording in brain slices with improved slicer technology.

    PubMed

    Geiger, J R P; Bischofberger, J; Vida, I; Fröbe, U; Pfitzinger, S; Weber, H J; Haverkampf, K; Jonas, P

    2002-01-01

    The use of advanced patch-clamp recording techniques in brain slices, such as simultaneous recording from multiple neurons and recording from dendrites or presynaptic terminals, demands slices of the highest quality. In this context the mechanics of the tissue slicer are an important factor. Ideally, a tissue slicer should generate large-amplitude and high-frequency movements of the cutting blade in a horizontal axis, with minimal vibrations in the vertical axis. We developed a vibroslicer that fulfils these in part conflicting requirements. The oscillator is a permanent-magnet-coil-leaf-spring system. Using an auto-resonant mechano-electrical feedback circuit, large horizontal oscillations (up to 3 mm peak-to-peak) with high frequency ( approximately 90 Hz) are generated. To minimize vertical vibrations, an adjustment mechanism was employed that allowed alignment of the cutting edge of the blade with the major axis of the oscillation. A vibroprobe device was used to monitor vertical vibrations during adjustment. The system is based on the shading of the light path between a light-emitting diode (LED) and a photodiode. Vibroprobe monitoring revealed that the vibroslicer, after appropriate adjustment, generated vertical vibrations of <1 microm, significantly less than many commercial tissue slicers. Light- and electron-microscopic analysis of surface layers of slices cut with the vibroslicer showed that cellular elements, dendritic processes and presynaptic terminals are well preserved under these conditions, as required for patch-clamp recording from these structures. PMID:11810221

  1. The effect of heat treatment on the gouging abrasion resistance of alloy white cast irons

    NASA Astrophysics Data System (ADS)

    Are, I. R. S.; Arnold, B. K.

    1995-02-01

    A series of heat treatments was employed to vary the microstructure of four commercially important alloy white cast irons, the wear resistance of which was then assessed by the ASTM jaw-crusher gouging abrasion test. Compared with the as-cast condition, standard austenitizing treatments produced a substantial increase in hardness, a marked decrease in the retained aus-tenite content in the matrix, and, in general, a significant improvement in gouging abrasion resistance. The gouging abrasion resistance tended to decline with increasing austenitizing tem-perature, although the changes in hardness and retained austenite content varied, depending on alloy composition. Subcritical heat treatment at 500 ° following hardening reduced the retained austenite content to values less than 10 pct, and in three of the alloys it caused a significant fall in both hardness and gouging abrasion resistance. The net result of the heat treatments was the development of optimal gouging abrasion resistance at intermediate levels of retained aus-tenite. The differing responses of the alloys to both high-temperature austenitizing treatments and to subcritical heat treatments at 500 ° were related to the effects of the differing carbon and alloying-element concentrations on changes in the M s temperature and secondary carbide precipitation.

  2. A novel cleaner for colloidal silica abrasive removal in post-Cu CMP cleaning

    NASA Astrophysics Data System (ADS)

    Haiwen, Deng; Baimei, Tan; Baohong, Gao; Chenwei, Wang; Zhangbing, Gu; Yan, Zhang

    2015-10-01

    A novel cleaning solution, named FA/O alkaline cleaner, was proposed and demonstrated in the removal of colloidal silica abrasives. In order to remove both the chemical and physical absorbed colloidal silica abrasives, an FA/OII chelating agent and non-ionic surfactant were added into the cleaner. By varying the concentration of chelating agent and non-ionic surfactant, a series of experiments were performed to determine the best cleaning results. This paper discusses the mechanism of the removal of colloidal silica abrasives with a FA/O alkaline cleaner. Based on the experiment results, it is concluded that both the FA/OII chelating and non-ionic surfactant could benefit the removal of colloidal silica abrasives. When the concentration of FA/OII chelating agent and FA/O non-ionic surfactant reached the optima value, it was demonstrated that silica abrasives could be removed efficiently by this novel cleaning solution. Project supported by the Specific Project Items No. 2 in National Long-Term Technology Development Plan (No. 2009zx02308-003) and the Hebei Province Department of Education Fund (No. QN2014208).

  3. Sliding and Abrasive Wear Behavior of WC-CoCr Coatings with Different Carbide Sizes

    NASA Astrophysics Data System (ADS)

    Thakur, Lalit; Arora, Navneet

    2013-02-01

    This study examines the sliding and abrasive wear behaviors of high-velocity oxy-fuel (HVOF)-sprayed WC-CoCr coatings with different WC grain sizes. The HVOF coating deposition was assisted by in-flight particle temperature and velocity measurement system. The powder feedstocks and their corresponding coatings were characterized by means of XRD and Field Emission Scanning Electron Microscope analysis. Hardness, porosity, and indentation fracture toughness of these coatings were calculated and compared with each other. Sliding wear resistance of these coatings was calculated using pin-on-disk tribometer (ASTM G99-90). The two-body abrasion was quantified by sliding the samples over silicon carbide (SiC) abrasive paper bonded to a rotating flat disk of auto-polisher. The mechanism of materials' removal in both the sliding and abrasive wears was studied and discussed on microstructural investigations. It was observed that fine grain WC-CoCr cermet coating exhibits higher sliding and abrasive wear resistances as compared with conventional cermet coating.

  4. Comparative evaluation of enamel abrasivity by toothbrush and velcro: An in vitro scanning electron microscope study

    PubMed Central

    Ojha, Saroj Kumar; Javdekar, Sadashiv Bhaskar; Dhir, Sangeeta

    2015-01-01

    Context: Plaque control has been shown to be pivotal in maintaining the optimal periodontal health. Mechanical plaque control is the most popular option for establishing the optimal oral health. Toothbrushes have been the novel tool for mechanical cleansing. However, the abrasive potential of the toothbrushes on the enamel surface is an area in gray. Aims: The aim of this in vitro study is to evaluate the abrasivity of the toothbrush versus the velcro fasteners. Materials and Methods: The mounted teeth of both the groups were subjected to abrasion test, and the tooth surfaces were observed for the possible abrasions from the oscillating strokes (toothbrush) and frictional contacts (hook and loop velcro) and examined under the scanning electron microscope. Results: Comparative assessment of both velcro (hook and loop) and toothbrush bristles did not reveal any evidence of abrasion on the tooth specimens. Conclusions: Veclro fasteners are safe and qualitatively at par to the manual toothbrush for their efficacy and efficiency in teeth cleansing PMID:26229264

  5. Effect of carbonitride precipitates on the abrasive wear behaviour of hardfacing alloy

    NASA Astrophysics Data System (ADS)

    Yang, Ke; Yu, Shengfu; Li, Yingbin; Li, Chenglin

    2008-06-01

    Hardfacing alloy of martensitic stainless steel expect higher abradability to be achieved through the addition of nitrogen being provided by the fine scale precipitation of complex carbonitride particles. Niobium and titanium as the most effective carbonitride alloying elements were added in the Fe-Cr13-Mn-N hardfacing alloy to get carbonitride precipitates. Carbonitride was systematically studied by optical microscopy, scanning electronic microscopy and energy spectrum analysis. Abrasive wear resistance of hardfacing alloy in as-welded and heat-treated conditions was tested by using the belt abrasion test apparatus where the samples slide against the abrasive belt. It is found that carbonitride particles in the hardfacing alloy are complex of Cr, Ti and Nb distributing on the grain boundary or matrix of the hardfacing alloy with different number and size in as-welded and heat-treated conditions. A large number of carbonitrides can be precipitated with very fine size (nanoscale) after heat treatment. As a result, the homogeneous distribution of very fine carbonitride particles can significantly improve the grain-abrasion wear-resisting property of the hardfacing alloy, and the mass loss is plastic deformation with minimum depth of grooving by abrasive particles and fine delamination.

  6. [Grinding of titanium. 1. Commercial and experimental wheels made of silicon carbide abrasives].

    PubMed

    Miyakawa, O; Watanabe, K; Okawa, S; Nakano, S; Shiokawa, N; Kobayashi, M; Tamura, H

    1990-01-01

    Cast titanium was ground with commercial and experimental wheels made of silicon carbide abrasives, and their grinding performance was investigated. With the vitrified wheels made of the GC abrasive, at a higher the wheel circumferential speed and heavier the grinding pressure, the cutting rate was greater, accompanied by violent wear of the wheel. Being independent of the wheel speed, the grinding ratio reached about 1 under pressure heavier than 100 gf. The MgO-MgCl2-bonded wheels of the C abrasive exhibited a similar tendency. The manner in which the wheel was moved over the work during grinding proved to be very important, compared with the Ni-Cr alloy as reported previously. Only depression of the wheel against the work resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn, due to oxidation of titanium. Even when the wheel was moved over the work, chip-formation process of the cutting edge was far from ideal, and the work surface was contaminated due to reaction of titanium with the abrasive. At a higher wheel circumferential speed, more chips were loaded or built-up in the wheel and strongly rubbed the work surface, resulting in violent wear of the wheel; loading and dislodging of such chips were repeated. PMID:2134811

  7. The effect of erosion and abrasion on surface properties of composite resin

    NASA Astrophysics Data System (ADS)

    Stoleriu, S.; Andrian, S.; Pancu, G.; Nica, I.; Munteanu, A.; Balan, A.; Iovan, G.

    2016-06-01

    The aim of the study was to evaluate the surface roughness of two commercial composite resins submitted to erosive attack, to abrasive wear and to association of erosive and abrasive challenge. Standardized samples of G-snial anterior (GC Company) and Essentia (GC Company) composite resins were randomly split in 6 groups. In group 1 the samples were maintained in artificial saliva until the evaluation of surface roughness. In group 2 the samples were submitted only to erosive attack, in group 3 only to abrasive challenge and in groups 4,5, and 6 the erosive attack was followed by abrasive challenge immediately (group 4), 30 minutes after the erosive attack (group 5) and one hour after the erosive attack (group 6). The specimens were evaluated using surface roughness measuring tester SJ-210 (Mitutoyo Corporation, Japan) and the mean surface roughness values (Ra, μm) of each specimen were registered. A significantly increase of both composite resins surface roughness was recorded after erosive attack and abrasive challenge. Toothbrushing 60 minutes after acidic contact determined no significant differences in surface roughness of composite resins.

  8. Image reconstruction and image quality evaluation for a 64-slice CT scanner with z-flying focal spot.

    PubMed

    Flohr, T G; Stierstorfer, K; Ulzheimer, S; Bruder, H; Primak, A N; McCollough, C H

    2005-08-01

    We present a theoretical overview and a performance evaluation of a novel z-sampling technique for multidetector row CT (MDCT), relying on a periodic motion of the focal spot in the longitudinal direction (z-flying focal spot) to double the number of simultaneously acquired slices. The z-flying focal spot technique has been implemented in a recently introduced MDCT scanner. Using 32 x 0.6 mm collimation, this scanner acquires 64 overlapping 0.6 mm slices per rotation in its spiral (helical) mode of operation, with the goal of improved longitudinal resolution and reduction of spiral artifacts. The longitudinal sampling distance at isocenter is 0.3 mm. We discuss in detail the impact of the z-flying focal spot technique on image reconstruction. We present measurements of spiral slice sensitivity profiles (SSPs) and of longitudinal resolution, both in the isocenter and off-center. We evaluate the pitch dependence of the image noise measured in a centered 20 cm water phantom. To investigate spiral image quality we present images of an anthropomorphic thorax phantom and patient scans. The full width at half maximum (FWHM) of the spiral SSPs shows only minor variations as a function of the pitch, measured values differ by less than 0.15 mm from the nominal values 0.6, 0.75, 1, 1.5, and 2 mm. The measured FWHM of the smallest slice ranges between 0.66 and 0.68 mm at isocenter, except for pitch 0.55 (0.72 mm). In a centered z-resolution phantom, bar patterns up to 15 lp/cm can be visualized independent of the pitch, corresponding to 0.33 mm longitudinal resolution. 100 mm off-center, bar patterns up to 14 lp/cm are visible, corresponding to an object size of 0.36 mm that can be resolved in the z direction. Image noise for constant effective mAs is almost independent of the pitch. Measured values show a variation of less than 7% as a function of the pitch, which demonstrates correct utilization of the applied radiation dose at any pitch. The product of image noise and

  9. Image reconstruction and image quality evaluation for a 64-slice CT scanner with z-flying focal spot

    SciTech Connect

    Flohr, T.G.; Stierstorfer, K.; Ulzheimer, S.; Bruder, H.; Primak, A.N.; McCollough, C.H.

    2005-08-15

    We present a theoretical overview and a performance evaluation of a novel z-sampling technique for multidetector row CT (MDCT), relying on a periodic motion of the focal spot in the longitudinal direction (z-flying focal spot) to double the number of simultaneously acquired slices. The z-flying focal spot technique has been implemented in a recently introduced MDCT scanner. Using 32x0.6 mm collimation, this scanner acquires 64 overlapping 0.6 mm slices per rotation in its spiral (helical) mode of operation, with the goal of improved longitudinal resolution and reduction of spiral artifacts. The longitudinal sampling distance at isocenter is 0.3 mm. We discuss in detail the impact of the z-flying focal spot technique on image reconstruction. We present measurements of spiral slice sensitivity profiles (SSPs) and of longitudinal resolution, both in the isocenter and off-center. We evaluate the pitch dependence of the image noise measured in a centered 20 cm water phantom. To investigate spiral image quality we present images of an anthropomorphic thorax phantom and patient scans. The full width at half maximum (FWHM) of the spiral SSPs shows only minor variations as a function of the pitch, measured values differ by less than 0.15 mm from the nominal values 0.6, 0.75, 1, 1.5, and 2 mm. The measured FWHM of the smallest slice ranges between 0.66 and 0.68 mm at isocenter, except for pitch 0.55 (0.72 mm). In a centered z-resolution phantom, bar patterns up to 15 lp/cm can be visualized independent of the pitch, corresponding to 0.33 mm longitudinal resolution. 100 mm off-center, bar patterns up to 14 lp/cm are visible, corresponding to an object size of 0.36 mm that can be resolved in the z direction. Image noise for constant effective mAs is almost independent of the pitch. Measured values show a variation of less than 7% as a function of the pitch, which demonstrates correct utilization of the applied radiation dose at any pitch. The product of image noise and square

  10. Local Application of Drugs to Study Nicotinic Acetylcholine Receptor Function in Mouse Brain Slices

    PubMed Central

    Engle, Staci E.; Broderick, Hilary J.; Drenan, Ryan M.

    2012-01-01

    Tobacco use leads to numerous health problems, including cancer, heart disease, emphysema, and stroke. Addiction to cigarette smoking is a prevalent neuropsychiatric disorder that stems from the biophysical and cellular actions of nicotine on nicotinic acetylcholine receptors (nAChRs) throughout the central nervous system. Understanding the various nAChR subtypes that exist in brain areas relevant to nicotine addiction is a major priority. Experiments that employ electrophysiology techniques such as whole-cell patch clamp or two-electrode voltage clamp recordings are useful for pharmacological characterization of nAChRs of interest. Cells expressing nAChRs, such as mammalian tissue culture cells or Xenopus laevis oocytes, are physically isolated and are therefore easily studied using the tools of modern pharmacology. Much progress has been made using these techniques, particularly when the target receptor was already known and ectopic expression was easily achieved. Often, however, it is necessary to study nAChRs in their native environment: in neurons within brain slices acutely harvested from laboratory mice or rats. For example, mice expressing "hypersensitive" nAChR subunits such as α4 L9′A mice 1 and α6 L9′S mice 2, allow for unambiguous identification of neurons based on their functional expression of a specific nAChR subunit. Although whole-cell patch clamp recordings from neurons in brain slices is routinely done by the skilled electrophysiologist, it is challenging to locally apply drugs such as acetylcholine or nicotine to the recorded cell within a brain slice. Dilution of drugs into the superfusate (bath application) is not rapidly reversible, and U-tube systems are not easily adapted to work with brain slices. In this paper, we describe a method for rapidly applying nAChR-activating drugs to neurons recorded in adult mouse brain slices. Standard whole-cell recordings are made from neurons in slices, and a second micropipette filled with a drug of

  11. Improvement in high stress abrasive wear property of steel by hardfacing

    SciTech Connect

    Kumar, S.; Mondal, D.P.; Khaira, H.K.; Jha, A.K.

    1999-12-01

    High stress abrasive wear behavior of mild steel, medium carbon steel, and hardfacing alloy has been studied to ascertain the extent of improvement in the wear properties after hardfacing of steel. High stress abrasive wear tests were carried out by sliding the specimen against the abrasive media consisting of silicon carbide particles, rigidly bonded on paper base and mounted on disk. Maximum wear was found in the case of mild steel followed by a medium carbon alloy steel and a hardfacing alloy. Different compositions of steels and constituent phases present led to different wear rates of the specimen. The extent of improvement in wear performance of steel due to hardfacing is quite appreciable (twice compared to mild steel). Microstructural examination of the wear surface has been carried out to understand the wear mechanism.

  12. Influence of material characteristics on the abrasive wear response of some hardfacing alloys

    SciTech Connect

    Jha, A.K.; Prasad, B.K.; Dasgupta, R.; Modi, O.P.

    1999-04-01

    This study examines the abrasive wear behavior of two iron-base hardfacing materials with different combinations of carbon and chromium after deposition on a steel substrate. Effects of applied load and sliding distance on the wear behavior of the specimens were studied. Operating material removal mechanisms also were analyzed through the scanning electron microscopy (SEM) examination of typical wear surfaces, subsurface regions, and debris particles. The results suggest a significant improvement in the wear resistance of the hardfaced layers over that of the substrate. Further, the specimens overlaid with the material with low carbon and high chromium contents attained better wear resistance than the one consisting of more carbon but less chromium. The former specimens also attained superior hardness. Smoother abrasion grooves on the wear surfaces and finer debris formation during the abrasion of the hardfaced samples were consistent with wear resistance superior to that of the substrate.

  13. The rock abrasion record at Gale Crater: Mars Science Laboratory results from Bradbury Landing to Rocknest

    NASA Astrophysics Data System (ADS)

    Bridges, N. T.; Calef, F. J.; Hallet, B.; Herkenhoff, K. E.; Lanza, N. L.; Le Mouélic, S.; Newman, C. E.; Blaney, D. L.; Pablo, M. A.; Kocurek, G. A.; Langevin, Y.; Lewis, K. W.; Mangold, N.; Maurice, S.; Meslin, P.-Y.; Pinet, P.; Renno, N. O.; Rice, M. S.; Richardson, M. E.; Sautter, V.; Sletten, R. S.; Wiens, R. C.; Yingst, R. A.

    2014-06-01

    Ventifacts, rocks abraded by wind-borne particles, are found in Gale Crater, Mars. In the eastward drive from "Bradbury Landing" to "Rocknest," they account for about half of the float and outcrop seen by Curiosity's cameras. Many are faceted and exhibit abrasion textures found at a range of scales, from submillimeter lineations to centimeter-scale facets, scallops, flutes, and grooves. The drive path geometry in the first 100 sols of the mission emphasized the identification of abrasion facets and textures formed by westerly flow. This upwind direction is inconsistent with predictions based on models and the orientation of regional dunes, suggesting that these ventifact features formed from very rare high-speed winds. The absence of active sand and evidence for deflation in the area indicates that most of the ventifacts are fossil features experiencing little abrasion today.

  14. New vibration-assisted magnetic abrasive polishing (VAMAP) method for microstructured surface finishing.

    PubMed

    Guo, Jiang; Kum, Chun Wai; Au, Ka Hing; Tan, Zhi'En Eddie; Wu, Hu; Liu, Kui

    2016-06-13

    In order to polish microstructured surface without deteriorating its profile, we propose a new vibration-assisted magnetic abrasive polishing (VAMAP) method. In this method, magnetic force guarantees that the magnetic abrasives can well contact the microstructured surface and access the corners of microstructures while vibration produces a relative movement between microstructures and magnetic abrasives. As the vibration direction is parallel to the microstructures, the profile of the microstructures will not be deteriorated. The relation between vibration and magnetic force was analyzed and the feasibility of this method was experimentally verified. The results show that after polishing, the surface finish around microstructures was significantly improved while the profile of microstructures was well maintained. PMID:27410370

  15. Abrasion-ablation model for neutron production in heavy ion reactions

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Wilson, John W.; Townsend, Lawrence W.

    1995-01-01

    In heavy ion reactions, neutron production at forward angles is observed to occur with a Gaussian shape that is centered near the beam energy and extends to energies well above that of the beam. This paper presents an abrasion-ablation model for making quantitative predictions of the neutron spectrum. To describe neutrons produced from the abrasion step of the reaction where the projectile and target overlap, the authors use the Glauber model and include effects of final-state interactions. They then use the prefragment mass distribution from abrasion with a statistical evaporation model to estimate the neutron spectrum resulting from ablation. Measurements of neutron production from Ne and Nb beams are compared with calculations, and good agreement is found.

  16. Non-abrasive particulate material for permeability alteration in subsurface formations

    SciTech Connect

    DePriester, C. L.

    1985-02-26

    An improved particulate material is disclosed for use in a method for altering the permeability of a gravity override or relatively high permeability path through a subsurface earth formation resulting from fluid injection into the subsurface formation. The method includes adding selectively sized, finely divided, amorphous non-abrasive particulate material to a fluid and injecting the fluid into the gravity override or relatively high permeability path to deposit the particulate material thus altering the permeability in the override, or relatively high permeability path. The particulate material may include graphite, carbon black, clay suspensions, quartz, or other minerals reduced in size range to behave as non-abrasive amorphous material which will present a non-abrasive characteristic in injection wells and if the particulate material is produced with formation fluids from the treated formation.

  17. Wear of artificial denture teeth by use of toothbrushes. Part 1: Abrasive wear of anterior teeth.

    PubMed

    Satoh, Y; Ohtani, K; Maejima, K; Morikawa, M; Matsuzu, M; Nagai, E; Toyoma, H; Ohwa, M; Ohki, K; Kaketani, M

    1990-12-01

    High-strength denture teeth (HS teeth) were developed in order to improve the hardness and wear resistance of conventional plastic denture teeth (PL teeth), while retaining their feature of easy occlusal adjustment. The objective of this study was to evaluate the abrasive wear resistance of HS teeth. We conducted wear tests and measured surface roughness using six types of anterior artificial teeth, i.e., three types of HS teeth and three types of PL teeth, the latter serving as the control. The results of the toothbrush abrasion test revealed that the HS teeth had about 5 times greater wear resistance than the PL teeth. It was also found that the type of artificial teeth and the number of abrasive wear-testing strokes had a significant (P less than 0.05) influence on the surface roughness of artificial teeth. PMID:2074493

  18. Abrasive wear: The efects of fibres size on oil palm empty fruit bunch polyester composite

    NASA Astrophysics Data System (ADS)

    Kasolang, S.; Kalam, A.; Ahmad, M. A.; Rahman, N. A.; Suhadah, W. N.

    2012-06-01

    This paper presents an experimental investigation carried out to determine the effect of palm oil empty fruit bunch (OPEFB) fibre size in dry sliding testing of polyester composite. These composite samples were produced by mixing raw OPEFB fibre with resin. The samples were prepared at different sizes of fibre (100, 125, 180 and 250μm). Abrasion Resistance Tester (TR-600) was used to carried out abrasive wear tests in dry sliding conditions. These tests were performed at room temperature for two different loads (10 and 30N) and at a constant sliding velocity of 1.4m/s. The specific wear rates of OPEFB polyester composites were obtained. The morphology of composite surface before and after tests was also examined using 3D microscope imaging. Preliminary work on thermal distribution at the abrasive wheel point was also conducted for selected samples.

  19. The rock abrasion record at Gale Crater: Mars Science Laboratory results from Bradbury Landing to Rocknest

    USGS Publications Warehouse

    Bridges, N.T.; Calef, F.J., III; Hallett, B.W.; Herkenhoff, Kenneth E.; Lanza, N.L.; Le Mouélic, S.; Newman, C.E.; Blaney, D.L.; de Pablo, M.A.; Kocurek, G.A.; Langevin, Y.; Lewis, K.W.; Mangold, N.; Maurice, S.; Meslin, P.-Y.; Pinet, P.; Renno, N.O.; Rice, CM.S.; Richardson, M.E.; Sautter, V.; Sletten, R.S.; Wiens, R.C.; Yingst, R.A.

    2014-01-01

    Ventifacts, rocks abraded by wind-borne particles, are found in Gale Crater, Mars. In the eastward drive from “Bradbury Landing” to “Rocknest,” they account for about half of the float and outcrop seen by Curiosity's cameras. Many are faceted and exhibit abrasion textures found at a range of scales, from submillimeter lineations to centimeter-scale facets, scallops, flutes, and grooves. The drive path geometry in the first 100 sols of the mission emphasized the identification of abrasion facets and textures formed by westerly flow. This upwind direction is inconsistent with predictions based on models and the orientation of regional dunes, suggesting that these ventifact features formed from very rare high-speed winds. The absence of active sand and evidence for deflation in the area indicates that most of the ventifacts are fossil features experiencing little abrasion today.

  20. CFD Based Erosion Modelling of Abrasive Waterjet Nozzle using Discrete Phase Method

    NASA Astrophysics Data System (ADS)

    Hakim Kamarudin, Naqib; Prasada Rao, A. K.; Azhari, Azmir

    2016-02-01

    In Abrasive Waterjet (AWJ) machining, the nozzle is the most critical component that influences the performance, precision and economy. Exposure to a high speed jet and abrasives makes it susceptible to wear erosion which requires for frequent replacement. The present works attempts to simulate the erosion of the nozzle wall using computational fluid dynamics. The erosion rate of the nozzle was simulated under different operating conditions. The simulation was carried out in several steps which is flow modelling, particle tracking and erosion rate calculation. Discrete Phase Method (DPM) and K-ε turbulence model was used for the simulation. Result shows that different operating conditions affect the erosion rate as well as the flow interaction of water, air and abrasives. The simulation results correlates well with past work.

  1. Photodetector Development for the Wheel Abrasion Experiment on the Sojourner Microrover of the Mars Pathfinder Mission

    NASA Technical Reports Server (NTRS)

    Wilt, David M.; Jenkins, Phillip P.; Scheiman, David A.

    1997-01-01

    On-board the Mars Pathfinder spacecraft, launched in December of 1996, is a small roving vehicle named Sojourner. On Sojourner is an experiment to determine the abrasive characteristics of the Martian surface, called the Wheel Abrasion Experiment (WAE). The experiment works as follows: one of the wheels of the rover has a strip of black anodized aluminum bonded to the tread. The aluminum strip has thin coatings of aluminum, nickel and platinum deposited in patches. There are five (5) patches or samples of each metal, and the patches range in thickness from 200 A to 1000 A. The different metals were chosen for their differing hardness and their environmental stability. As the wheel is spun in the Martian soil, the thin patches of metal are abraded away, exposing the black anodization. The abrasion is monitored by measuring the amount of light reflected off of the samples. A photodetector was developed for this purpose, and that is the subject of this paper.

  2. Abrasion, erosion and scuffing resistance of carbide and oxide ceramic thermal sprayed coatings for different applications

    NASA Astrophysics Data System (ADS)

    Barbezat, G.; Nicoll, A. R.; Sickinger, A.

    1993-04-01

    In the area of antiwear coatings, carbide-containing coatings and oxide ceramic coatings are applied using different thermal spray processes in the form of individual layers. In many industries these coatings have become technically significant on components where wear and friction can cause critical damage in the form of abrasion, erosion and scuffing together with corrosion. Carbide-containing and ceramic coatings have been produced with different thermal spray processes for the determination of abrasive, adhesive and erosive wear resistance. Two types of abrasion test, namely an adhesion wear test and an erosion test in water at a high velocity, were used for the characterization of wear resistance under different conditions. The coatings were also characterized with regard to microstructure, composition and fracture toughness. The influence of the thermal spraying process parameters on the microstructure is presented together with the influence of the microstructure on the behavior of the coatings under simulated service conditions.

  3. Considerations on the European Standard EN 14157 Test Methods: Abrasion Resistance of Natural Stones Used for Flooring in Buildings

    NASA Astrophysics Data System (ADS)

    Karaca, Z.; Günes Yılmaz, N.; Goktan, R. M.

    2012-01-01

    In Europe, the Wide Wheel abrasion (WWA) test and the Böhme abrasion (BA) test are among the most widely used standard test methods for determining abrasion resistance of natural stones, the former being the reference test method in EN 14157 Standard. However, it is stated in the Annex-A (Informative) of EN 14157 Standard that very limited data are available to provide correlations between these two test methods. To be able to fill this gap, in this study, 25 different natural stones belonging to sedimentary, metamorphic and igneous groups were tested for their abrasion resistance as well as physico-mechanical properties. Also, for a better interpretation of abrasion resistance characteristics of the tested stone materials, relationships between abrasion resistance and physico-mechanical properties were statistically examined. A statistically significant linear correlation ( R 2 = 0.85; P value = 0.000) was established between the WWA test and the BA test, which could be used in practice for converting the measured abrasion resistance values from one testing method to another. It was also found that the correlation between these two test methods improved significantly ( R 2 = 0.93; P value = 0.001) when relatively high-porosity stone materials (porosity ≥1%) were separately evaluated. Both methods of abrasion resistance employed in the present study showed statistically significant linear correlations with uniaxial compressive strength and Brazilian tensile strength, the former proving to be a more influencing parameter on resistance to abrasion. Also, from the point view of representing actual abrasion mechanism of stone materials in practice, the necessity of simulating multi-directional foot traffic in abrasion testing methods was discussed. In this respect, the reference test method in the EN 14157 Standard was criticized for not fully meeting this requirement. It was also pointed out that the reference method could have some drawbacks when applied to coarse

  4. Brain tissue slice thickness monitored by ion-profile measurement.

    PubMed

    Lipinski, H G

    1992-04-01

    The thickness of a brain tissue slice preparation governs the amount of time required for substances to diffuse from the bathing solution to preparation. Slice thickness may increase during the experiment, e.g., in cases of hypoxia where osmotic pressure within the tissue changes, enabling water to enter the preparation. With increasing slice thickness diffusion paths from the bath to central layers of the preparation increase possibly resulting in an insufficient O2 supply to central layers. Therefore, the actual slice thickness should be monitored during the experiment especially in cases where osmolarity is changed or during hypoxia. This paper describes a simple method to monitor the actual slice thickness using ion profiles measured by ion selective micro-electrodes driven at a constant rate of approximately 10 microns/s (sample rate ca. 10/s). The method is based on steep changes in the concentration gradients at the upper and lower surfaces of the preparation induced by simple diffusion in the presence of concentration gradients between the non-tortuous bath and the tortuous tissue. The thickness of the preparation is derived from the location of the steep gradient changes as reflected by the registered profile. PMID:1405733

  5. Diffusion of radiotracers in normal and ischemic brain slices.

    PubMed

    Patlak, C S; Hospod, F E; Trowbridge, S D; Newman, G C

    1998-07-01

    Diffusion in the extracellular space (ECS) is important in physiologic and pathologic brain processes but remains poorly understood. To learn more about factors influencing tissue diffusion and the role of diffusion in solute-tissue interactions, particularly during cerebral ischemia, we have studied the kinetics of several radiotracers in control and hypoxic 450-microm hippocampal slices and in 1,050-microm thick slices that model the ischemic penumbra. Kinetics were analyzed by nonlinear least squares methods using models that combine extracellular diffusion with tissue compartments in series or in parallel. Studies with 14C-polyethylene glycol confirmed prior measurements of extracellular volume and that ECS shrinks during ischemia. Separating diffusion from transport also revealed large amounts of 45Ca that bind to or enter brain as well as demonstrating a small, irreversibly bound compartment during ischemia. The rapidity of 3H2O entry into cells made it impossible for us to distinguish intracellular from extracellular diffusion. The diffusion-compartment analysis of 3-O-methylglucose data appears to indicate that 5 mmol/L glucose is inadequate to support glycolysis fully in thick slices. Unexpectedly, the diffusion coefficient for all four tracers rose in thick slices compared with thin slices, suggesting that ECS becomes less tortuous in the penumbra. PMID:9663508

  6. Short pulse generation by laser slicing at NSLSII

    SciTech Connect

    Yu, L.; Blednykh, A.; Guo, W.; Krinsky, S.; Li, Y.; Shaftan, T.; Tchoubar, O.; Wang, G.; Willeke, F.; Yang, L.

    2011-03-28

    We discuss an upgrade R&D project for NSLSII to generate sub-pico-second short x-ray pulses using laser slicing. We discuss its basic parameters and present a specific example for a viable design and its performance. Since the installation of the laser slicing system into the storage ring will break the symmetry of the lattice, we demonstrate it is possible to recover the dynamical aperture to the original design goal of the ring. There is a rapid growth of ultrafast user community interested in science using sub-pico-second x-ray pulses. In BNL's Short Pulse Workshop, the discussion from users shows clearly the need for a sub-pico-second pulse source using laser slicing method. In the proposal submitted following this workshop, NSLS team proposed both hard x-ray and soft x-ray beamlines using laser slicing pulses. Hence there is clearly a need to consider the R&D efforts of laser slicing short pulse generation at NSLSII to meet these goals.

  7. Rapid and quantitative discrimination of tumour cells on tissue slices

    NASA Astrophysics Data System (ADS)

    Huang, Kai-Wen; Chieh, Jen-Jie; Liao, Shu-Hsien; Wei, Wen-Chun; Hsiao, Pei-Yi; Yang, Hong-Chang; Horng, Herng-Er

    2016-06-01

    After a needle biopsy, immunohistochemistry is generally used to stain tissue slices for clinically confirming tumours. Currently, tissue slices are immersed in a bioprobe-linked fluorescent reagent for several minutes, washed to remove the unbound reagent, and then observed using a fluorescence microscope. However, the observation must be performed by experienced pathologists, and producing a qualitative analysis is time consuming. Therefore, this study proposes a novel scanning superconducting quantum interference device biosusceptometry (SSB) method for avoiding these drawbacks. First, stain reagents were synthesised for the dual modalities of fluorescent and magnetic imaging by combining iron-oxide magnetic nanoparticles and the currently used fluorescent reagent. The reagent for the proposed approach was stained using the same procedure as that for the current fluorescent reagent, and tissue slices were rapidly imaged using the developed SSB for obtaining coregistered optical and magnetic images. Analysing the total intensity of magnetic spots in SSB images enables quantitatively determining the tumour cells of tissue slices. To confirm the magnetic imaging results, a traditional observation methodology entailing the use of a fluorescence microscope was also performed as the gold standard. This study determined high consistency between the fluorescent and magnetic spots in different regions of the tissue slices, demonstrating the feasibility of the proposed approach, which will benefit future clinical pathology.

  8. Rapid and quantitative discrimination of tumour cells on tissue slices.

    PubMed

    Huang, Kai-Wen; Chieh, Jen-Jie; Liao, Shu-Hsien; Wei, Wen-Chun; Hsiao, Pei-Yi; Yang, Hong-Chang; Horng, Herng-Er

    2016-06-10

    After a needle biopsy, immunohistochemistry is generally used to stain tissue slices for clinically confirming tumours. Currently, tissue slices are immersed in a bioprobe-linked fluorescent reagent for several minutes, washed to remove the unbound reagent, and then observed using a fluorescence microscope. However, the observation must be performed by experienced pathologists, and producing a qualitative analysis is time consuming. Therefore, this study proposes a novel scanning superconducting quantum interference device biosusceptometry (SSB) method for avoiding these drawbacks. First, stain reagents were synthesised for the dual modalities of fluorescent and magnetic imaging by combining iron-oxide magnetic nanoparticles and the currently used fluorescent reagent. The reagent for the proposed approach was stained using the same procedure as that for the current fluorescent reagent, and tissue slices were rapidly imaged using the developed SSB for obtaining coregistered optical and magnetic images. Analysing the total intensity of magnetic spots in SSB images enables quantitatively determining the tumour cells of tissue slices. To confirm the magnetic imaging results, a traditional observation methodology entailing the use of a fluorescence microscope was also performed as the gold standard. This study determined high consistency between the fluorescent and magnetic spots in different regions of the tissue slices, demonstrating the feasibility of the proposed approach, which will benefit future clinical pathology. PMID:27138705

  9. Fractal Segmentation and Clustering Analysis for Seismic Time Slices

    NASA Astrophysics Data System (ADS)

    Ronquillo, G.; Oleschko, K.; Korvin, G.; Arizabalo, R. D.

    2002-05-01

    Fractal analysis has become part of the standard approach for quantifying texture on gray-tone or colored images. In this research we introduce a multi-stage fractal procedure to segment, classify and measure the clustering patterns on seismic time slices from a 3-D seismic survey. Five fractal classifiers (c1)-(c5) were designed to yield standardized, unbiased and precise measures of the clustering of seismic signals. The classifiers were tested on seismic time slices from the AKAL field, Cantarell Oil Complex, Mexico. The generalized lacunarity (c1), fractal signature (c2), heterogeneity (c3), rugosity of boundaries (c4) and continuity resp. tortuosity (c5) of the clusters are shown to be efficient measures of the time-space variability of seismic signals. The Local Fractal Analysis (LFA) of time slices has proved to be a powerful edge detection filter to detect and enhance linear features, like faults or buried meandering rivers. The local fractal dimensions of the time slices were also compared with the self-affinity dimensions of the corresponding parts of porosity-logs. It is speculated that the spectral dimension of the negative-amplitude parts of the time-slice yields a measure of connectivity between the formation's high-porosity zones, and correlates with overall permeability.

  10. Abrasion Testing of Candidate Outer Layer Fabrics for Lunar EVA Space Suits

    NASA Technical Reports Server (NTRS)

    Mitchell, Kathryn C.

    2010-01-01

    During the Apollo program, the space suit outer layer fabrics were badly abraded after just a few Extravehicular Activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots, which penetrated the outer layer fabric into the thermal protection layers after less than eight hours of surface operations. Current plans for the Constellation Space Suit Element require the space suits to support hundreds of hours of EVA on the Lunar surface, creating a challenge for space suit designers to utilize materials advances made over the last forty years and improve upon the space suit fabrics used in the Apollo program. A test methodology has been developed by the NASA Johnson Space Center Crew and Thermal Systems Division for establishing comparative abrasion wear characteristics between various candidate space suit outer layer fabrics. The abrasion test method incorporates a large rotary drum tumbler with rocks and loose lunar simulant material to induce abrasion in fabric test cylinder elements, representative of what might occur during long term planetary surface EVAs. Preliminary materials screening activities were conducted to determine the degree of wear on representative space suit outer layer materials and the corresponding dust permeation encountered between subsequent sub -layers of thermal protective materials when exposed to a simulated worst case eight hour EVA. The test method was used to provide a preliminary evaluation of four candidate outer layer fabrics for future planetary surface space suit applications. This Paper provides a review of previous abrasion studies on space suit fabrics, details the methodologies used for abrasion testing in this particular study, and shares the results and conclusions of the testing.

  11. Abrasion Testing of Candidate Outer Layer Fabrics for Lunar EVA Space Suits

    NASA Technical Reports Server (NTRS)

    Mitchell, Kathryn

    2009-01-01

    During the Apollo program, the space suit outer layer fabrics were severely abraded after just a few Extravehicular Activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots, which penetrated the outer layer fabric into the thermal protection layers after less than eight hours of surface operations. Current plans for the Constellation Space Suit Element require the space suits to support hundreds of hours of EVA on the Lunar surface, creating a challenge for space suit designers to utilize materials advances made over the last forty years and improve upon the space suit fabrics used in the Apollo program. A test methodology has been developed by the NASA Johnson Space Center Crew and Thermal Systems Division for establishing comparative abrasion wear characteristics between various candidate space suit outer layer fabrics. The abrasion test method incorporates a large rotary drum tumbler with rocks and loose lunar simulant material to induce abrasion in fabric test cylinder elements, representative of what might occur during long term planetary surface EVAs. Preliminary materials screening activities were conducted to determine the degree of wear on representative space suit outer layer materials and the corresponding dust permeation encountered between subsequent sub-layers of thermal protective materials when exposed to a simulated worst case eight hour EVA. The test method was used to provide a preliminary evaluation of four candidate outer layer fabrics for future planetary surface space suit applications. This paper provides a review of previous abrasion studies on space suit fabrics, details the methodologies used for abrasion testing in this particular study, shares the results of the testing, and provides recommendations for future work.

  12. Brushing abrasion of eroded dentin after application of sodium fluoride solutions.

    PubMed

    Attin, T; Zirkel, C; Hellwig, E

    1998-01-01

    The aim of the present in vitro study was to evaluate the influence of sodium fluoride solutions on brushing abrasion of eroded dentin. Dentin specimens were prepared from 60 bovine incisors. The specimens were embedded in acrylic resin, ground flat, polished and subsequently covered with tape exposing an area of 1.8 mm x 10.0 mm in the center of the exposed dentin. The samples were alternatingly stored in a demineralizing solution (5 min) and a remineralizing solution (1 min) for 5 times. The erosive soft drink Sprite light(R) served as a demineralizing solution and artificial saliva was used as a remineralizing solution. Prior to storage in artificial saliva 15 specimens were each treated for 1 min with 250 and 2,000 ppm fluoride solution, respectively. Fifteen specimens were treated with distilled water instead of the fluoride solution (= eroded controls). The remaining samples were neither eroded with the soft drink nor fluoridated (= uneroded controls). After each immersion in artificial saliva the specimens were submitted to abrasion in a toothbrushing machine. After 5 demineralization-remineralization brushing cycles the total amount of tooth wear due to erosion and subsequent abrasion was profilometrically evaluated. Statistical analysis revealed the significantly lowest wear in the uneroded controls and the highest amount of abrasion in the eroded controls. Application of the fluoride solutions increased the wear resistance of the eroded dentin specimens, showing significantly better protection by the high-concentration compared to the low-concentration solution. The susceptibility to abrasion of the eroded dentin specimens treated with the high-concentration fluoride solution did not differ significantly from the uneroded dentin samples. It is concluded that application of 2,000 ppm sodium fluoride solutions immediately before toothbrushing significantly reduces abrasion of eroded dentin in vitro. PMID:9701659

  13. Microstructural effects in abrasive wear. Quarterly progress report, June 1981-January 1982

    SciTech Connect

    Kosel, T.H.; Rao, C.M.; Fernandes, M.T.; Fiore, N.F.

    1982-02-24

    This report describes research aimed at establishing quantitative relationships between microstructure and wear resistance of highly alloyed materials, including high-Cr white irons and powder metallurgy (PM) alloys now used or potentially to be used in coal mining, handling, and gasification. The specific types of wear under study are low-stress abrasion and gouging wear encountered in mining, coal conversion, and transfer applications. Recent work has concentrated on analysis of results. The many detailed observations obtained in the work on scratch test simulations of abrasive wear mechanisms have been summarized in drafts of three papers. The first, a study of abrasive wear mechanisms using diamond and alumina scratch tests, was included as an appendix to Quarterly Report 16/17 and has been accepted for publication in the journal Wear. Revision of the other two papers is in progress. Two papers representing our analysis of results are included as appendices to this report. The first, abrasion in multiphase alloys, was presented at the NACE conference on corrosion-erosion-wear of materials at Berkeley, California in January 1982, and will be published in the proceedings. The second, on a deformation-induced phase transformation during abrasive wear of Co-base alloys, is being submitted for publication in Metallurgical Transactions. In addition, work on the gouging abrasion resistance of the previously tested high Cr-Mo white cast irons is completed. The abstract of a short paper on the results is included as an appendix. (Note: since the appendices are, or will be, available in the open literature they have been removed from the report.)

  14. Patch-clamp capacitance measurements and Ca²⁺ imaging at single nerve terminals in retinal slices.

    PubMed

    Kim, Mean-Hwan; Vickers, Evan; von Gersdorff, Henrique

    2012-01-01

    Visual stimuli are detected and conveyed over a wide dynamic range of light intensities and frequency changes by specialized neurons in the vertebrate retina. Two classes of retinal neurons, photoreceptors and bipolar cells, accomplish this by using ribbon-type active zones, which enable sustained and high-throughput neurotransmitter release over long time periods. ON-type mixed bipolar cell (Mb) terminals in the goldfish retina, which depolarize to light stimuli and receive mixed rod and cone photoreceptor input, are suitable for the study of ribbon-type synapses both due to their large size (~10-12 μm diameter) and to their numerous lateral and reciprocal synaptic connections with amacrine cell dendrites. Direct access to Mb bipolar cell terminals in goldfish retinal slices with the patch-clamp technique allows the measurement of presynaptic Ca(2+) currents, membrane capacitance changes, and reciprocal synaptic feedback inhibition mediated by GABA(A) and GABA(C) receptors expressed on the terminals. Presynaptic membrane capacitance measurements of exocytosis allow one to study the short-term plasticity of excitatory neurotransmitter release. In addition, short-term and long-term plasticity of inhibitory neurotransmitter release from amacrine cells can also be investigated by recordings of reciprocal feedback inhibition arriving at the Mb terminal. Over short periods of time (e.g. ~10 s), GABAergic reciprocal feedback inhibition from amacrine cells undergoes paired-pulse depression via GABA vesicle pool depletion. The synaptic dynamics of retinal microcircuits in the inner plexiform layer of the retina can thus be directly studied. The brain-slice technique was introduced more than 40 years ago but is still very useful for the investigation of the electrical properties of neurons, both at the single cell soma, single dendrite or axon, and microcircuit synaptic level. Tissues that are too small to be glued directly onto the slicing chamber are often first embedded

  15. Abrasion Resistance of as-Cast High-Chromium Cast Iron

    NASA Astrophysics Data System (ADS)

    Pokusová, Marcela; Berta, Igor; Šooš, Ľubomír

    2014-12-01

    High chromium cast irons are widely used as abrasion resistant materials. Their properties and wear resistance depend on carbides and on the nature of the matrix supporting these carbides. The paper presents test results of irons which contain (in wt.%) 18-22 Cr and 2-5 C, and is alloyed by 1.7 Mo + 5 Ni + 2 Mn to improve the toughness. Tests showed as-cast irons with mostly austenitic matrix achieved hardness 36-53 HRC but their relative abrasion-resistance was higher than the tool steel STN 19436 heat treated on hardness 60 HRC.

  16. Comparison of the abrasive wear resistance between amalgams, hybrid composite material and different dental cements.

    PubMed

    Gil, F J; Espias, A; Sánchez, L A; Planell, J A

    1999-12-01

    This paper reports on the abrasion wear of various restorative dental materials (three amalgams and two dental cements and a hybrid composite material) commonly used in dentistry. The mechanical properties, surface roughness and the volume loss by abrasion were determined for the different materials studied. The results showed a better profile for the amalgams versus the composite materials due to the failure of the polymeric matrix of the latter materials. However, the amalgams exhibited corrosion observed by means of Scanning Electron Microscopy. PMID:10907431

  17. Imaging neuronal responses in slice preparations of vomeronasal organ expressing a genetically encoded calcium sensor.

    PubMed

    Ma, Limei; Haga-Yamanaka, Sachiko; Yu, Qingfeng Elden; Qiu, Qiang; Kim, Sangseong; Yu, C Ron

    2011-01-01

    The vomeronasal organ (VNO) detects chemosensory signals that carry information about the social, sexual and reproductive status of the individuals within the same species. These intraspecies signals, the pheromones, as well as signals from some predators, activate the vomeronasal sensory neurons (VSNs) with high levels of specificity and sensitivity. At least three distinct families of G-protein coupled receptors, V1R, V2R and FPR, are expressed in VNO neurons to mediate the detection of the chemosensory cues. To understand how pheromone information is encoded by the VNO, it is critical to analyze the response profiles of individual VSNs to various stimuli and identify the specific receptors that mediate these responses. The neuroepithelia of VNO are enclosed in a pair of vomer bones. The semi-blind tubular structure of VNO has one open end (the vomeronasal duct) connecting to the nasal cavity. VSNs extend their dendrites to the lumen part of the VNO, where the pheromone cues are in contact with the receptors expressed at the dendritic knobs. The cell bodies of the VSNs form pseudo-stratified layers with V1R and V2R expressed in the apical and basal layers respectively. Several techniques have been utilized to monitor responses of VSNs to sensory stimuli. Among these techniques, acute slice preparation offers several advantages. First, compared to dissociated VSNs, slice preparations maintain the neurons in their native morphology and the dendrites of the cells stay relatively intact. Second, the cell bodies of the VSNs are easily accessible in coronal slice of the VNO to allow electrophysiology studies and imaging experiments as compared to whole epithelium and whole-mount preparations. Third, this method can be combined with molecular cloning techniques to allow receptor identification. Sensory stimulation elicits strong Ca2+ influx in VSNs that is indicative of receptor activation. We thus develop transgenic mice that express G-CaMP2 in the olfactory sensory

  18. Fluid dynamic lateral slicing of high tensile strength carbon nanotubes.

    PubMed

    Vimalanathan, Kasturi; Gascooke, Jason R; Suarez-Martinez, Irene; Marks, Nigel A; Kumari, Harshita; Garvey, Christopher J; Atwood, Jerry L; Lawrance, Warren D; Raston, Colin L

    2016-01-01

    Lateral slicing of micron length carbon nanotubes (CNTs) is effective on laser irradiation of the materials suspended within dynamic liquid thin films in a microfluidic vortex fluidic device (VFD). The method produces sliced CNTs with minimal defects in the absence of any chemical stabilizers, having broad length distributions centred at ca 190, 160 nm and 171 nm for single, double and multi walled CNTs respectively, as established using atomic force microscopy and supported by small angle neutron scattering solution data. Molecular dynamics simulations on a bent single walled carbon nanotube (SWCNT) with a radius of curvature of order 10 nm results in tearing across the tube upon heating, highlighting the role of shear forces which bend the tube forming strained bonds which are ruptured by the laser irradiation. CNT slicing occurs with the VFD operating in both the confined mode for a finite volume of liquid and continuous flow for scalability purposes. PMID:26965728

  19. Approach to combined-function magnets via symplectic slicing

    NASA Astrophysics Data System (ADS)

    Titze, M.

    2016-05-01

    In this article we describe how to obtain symplectic "slice" maps for combined-function magnets, by using a method of generating functions. A feature of this method is that one can use an unexpanded and unsplit Hamiltonian. From such a slice map we obtain a first-order map which is symplectic at the closed orbit. We also obtain a symplectic kick map. Both results were implemented into the widely used program MAD-X to regain, in particular, the twiss parameters for the sliced model of the Proton Synchrotron at CERN. In addition, we obtain recursion equations for symplectic maps of general time-dependent Hamiltonians, which might be useful even beyond the scope of accelerator physics.

  20. Fluid dynamic lateral slicing of high tensile strength carbon nanotubes

    PubMed Central

    Vimalanathan, Kasturi; Gascooke, Jason R.; Suarez-Martinez, Irene; Marks, Nigel A.; Kumari, Harshita; Garvey, Christopher J.; Atwood, Jerry L.; Lawrance, Warren D.; Raston, Colin L.

    2016-01-01

    Lateral slicing of micron length carbon nanotubes (CNTs) is effective on laser irradiation of the materials suspended within dynamic liquid thin films in a microfluidic vortex fluidic device (VFD). The method produces sliced CNTs with minimal defects in the absence of any chemical stabilizers, having broad length distributions centred at ca 190, 160 nm and 171 nm for single, double and multi walled CNTs respectively, as established using atomic force microscopy and supported by small angle neutron scattering solution data. Molecular dynamics simulations on a bent single walled carbon nanotube (SWCNT) with a radius of curvature of order 10 nm results in tearing across the tube upon heating, highlighting the role of shear forces which bend the tube forming strained bonds which are ruptured by the laser irradiation. CNT slicing occurs with the VFD operating in both the confined mode for a finite volume of liquid and continuous flow for scalability purposes. PMID:26965728

  1. Drying kinetics and colour change of lemon slices

    NASA Astrophysics Data System (ADS)

    Darvishi, Hosain; Khoshtaghaza, Mohammad H.; Minaei, Saeid

    2014-03-01

    The effect of microwave-convective heating on drying characteristics and colour change of lemon slices was investigated. The drying experiments were carried out at 180, 360, 540 and 720Wand at 22°C, with air velocity of 1ms-1. The values of effective moisture diffusivity were found to be in the range between 1.87 10-8 and 3.95 10-8 m2 s-1, and the activation energy was estimated to be 10.91 Wg-1. The drying data were fitted with ten mathematical models available in the literature. The model describing drying kinetics of lemon slices in the best way was found. The colour change of the dried lemon slices was analysed and considered as a quality index affecting the drying quality of the product. The values of lightness/darkness, yellowness/blueness and hue angle increased, while the value of redness/greenness decreased with increasing microwave power.

  2. Plastinated heart slices aid echocardiographic interpretation in the dog.

    PubMed

    Gómez, Alejandro; Del Palacio, Josefa F; Latorre, Rafael; Henry, Robert W; Sarriá, Ricardo; Albors, Octavio López

    2012-01-01

    Our aim was to compare plastinated sections of the canine heart with corresponding two-dimensional (2D) echocardiographic images. Thirteen dog hearts were fixed by dilation and then processed by the S10 silicon plastination method (Biodur). Two dogs without evidence of cardiac disease were imaged using 2D echocardiography so as to obtain a complete series of the standard right and left parasternal images, which were compared with corresponding plastinated slices obtained by knife sectioning of the hearts. The plastinated slices revealed the internal anatomy of the heart with great detail and were particularly useful to display the spatial relationship between complex anatomic structures. The plastinated slices corresponded accurately with the echocardiographic images. Because of the dilation of the right heart during the fixation process, it was not possible to obtain plastinated specimens in ventricular systole. This paper may be a reference atlas for assisting 2D echocardiography interpretation. PMID:22092521

  3. Fluid dynamic lateral slicing of high tensile strength carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Vimalanathan, Kasturi; Gascooke, Jason R.; Suarez-Martinez, Irene; Marks, Nigel A.; Kumari, Harshita; Garvey, Christopher J.; Atwood, Jerry L.; Lawrance, Warren D.; Raston, Colin L.

    2016-03-01

    Lateral slicing of micron length carbon nanotubes (CNTs) is effective on laser irradiation of the materials suspended within dynamic liquid thin films in a microfluidic vortex fluidic device (VFD). The method produces sliced CNTs with minimal defects in the absence of any chemical stabilizers, having broad length distributions centred at ca 190, 160 nm and 171 nm for single, double and multi walled CNTs respectively, as established using atomic force microscopy and supported by small angle neutron scattering solution data. Molecular dynamics simulations on a bent single walled carbon nanotube (SWCNT) with a radius of curvature of order 10 nm results in tearing across the tube upon heating, highlighting the role of shear forces which bend the tube forming strained bonds which are ruptured by the laser irradiation. CNT slicing occurs with the VFD operating in both the confined mode for a finite volume of liquid and continuous flow for scalability purposes.

  4. Fast parallel algorithm for slicing STL based on pipeline

    NASA Astrophysics Data System (ADS)

    Ma, Xulong; Lin, Feng; Yao, Bo

    2016-04-01

    In Additive Manufacturing field, the current researches of data processing mainly focus on a slicing process of large STL files or complicated CAD models. To improve the efficiency and reduce the slicing time, a parallel algorithm has great advantages. However, traditional algorithms can't make full use of multi-core CPU hardware resources. In the paper, a fast parallel algorithm is presented to speed up data processing. A pipeline mode is adopted to design the parallel algorithm. And the complexity of the pipeline algorithm is analyzed theoretically. To evaluate the performance of the new algorithm, effects of threads number and layers number are investigated by a serial of experiments. The experimental results show that the threads number and layers number are two remarkable factors to the speedup ratio. The tendency of speedup versus threads number reveals a positive relationship which greatly agrees with the Amdahl's law, and the tendency of speedup versus layers number also keeps a positive relationship agreeing with Gustafson's law. The new algorithm uses topological information to compute contours with a parallel method of speedup. Another parallel algorithm based on data parallel is used in experiments to show that pipeline parallel mode is more efficient. A case study at last shows a suspending performance of the new parallel algorithm. Compared with the serial slicing algorithm, the new pipeline parallel algorithm can make full use of the multi-core CPU hardware, accelerate the slicing process, and compared with the data parallel slicing algorithm, the new slicing algorithm in this paper adopts a pipeline parallel model, and a much higher speedup ratio and efficiency is achieved.

  5. Fast parallel algorithm for slicing STL based on pipeline

    NASA Astrophysics Data System (ADS)

    Ma, Xulong; Lin, Feng; Yao, Bo

    2016-05-01

    In Additive Manufacturing field, the current researches of data processing mainly focus on a slicing process of large STL files or complicated CAD models. To improve the efficiency and reduce the slicing time, a parallel algorithm has great advantages. However, traditional algorithms can't make full use of multi-core CPU hardware resources. In the paper, a fast parallel algorithm is presented to speed up data processing. A pipeline mode is adopted to design the parallel algorithm. And the complexity of the pipeline algorithm is analyzed theoretically. To evaluate the performance of the new algorithm, effects of threads number and layers number are investigated by a serial of experiments. The experimental results show that the threads number and layers number are two remarkable factors to the speedup ratio. The tendency of speedup versus threads number reveals a positive relationship which greatly agrees with the Amdahl's law, and the tendency of speedup versus layers number also keeps a positive relationship agreeing with Gustafson's law. The new algorithm uses topological information to compute contours with a parallel method of speedup. Another parallel algorithm based on data parallel is used in experiments to show that pipeline parallel mode is more efficient. A case study at last shows a suspending performance of the new parallel algorithm. Compared with the serial slicing algorithm, the new pipeline parallel algorithm can make full use of the multi-core CPU hardware, accelerate the slicing process, and compared with the data parallel slicing algorithm, the new slicing algorithm in this paper adopts a pipeline parallel model, and a much higher speedup ratio and efficiency is achieved.

  6. Thin slice expert testimony and mock trial deliberations.

    PubMed

    Parrott, Caroline Titcomb; Brodsky, Stanley L; Wilson, Jennifer Kelly

    2015-01-01

    This study examined impressions of expert witness testimony in a not guilty by reason of insanity defense on two outcomes: witness's credibility and verdict. Borrowing in part from the "thin slice" methodology, we assessed outcomes in a 2 (deliberating vs. non-deliberating jurors) × 3 (length of videotaped testimony) between-subjects design. In 30 mock juries, 188 participants viewed the testimony by a forensic psychologist; then half of the juries deliberated. Thinner slices of the testimony were defined by the lower (30s long) and upper (5 min long) temporal bounds in the literature. The third, fuller testimony condition was 10 min long and served as the accuracy marker for the shorter sliced exposures. We aimed to explore potential consequences to jurors relying on impressions of the expert, and his or her opinion, and to test that effect post deliberation. Accounting for deliberation, brief impressions of expert credibility generally exerted a similar influence on credibility to fuller considerations. The essential finding was that a two-way interaction emerged from time slice and deliberation on verdict for jurors in the 30s condition. Overall, predictive accuracy was found in the 5 min slice, yet accuracy was not supported in the predictions based on the shortest slice. Individually-formed impressions are not likely to translate to the verdict ballot post-deliberation. Instead, brief impressions are likely to be heavily influenced by deliberation. Implications for understanding how impression-based testimony evaluations translate from the jury box to the deliberation room are discussed. PMID:26346686

  7. Modification of a Colliculo-thalamocortical Mouse Brain Slice, Incorporating 3-D printing of Chamber Components and Multi-scale Optical Imaging.

    PubMed

    Slater, Bernard J; Fan, Anthony Y; Stebbings, Kevin A; Saif, M Taher A; Llano, Daniel A

    2015-01-01

    The ability of the brain to process sensory information relies on both ascending and descending sets of projections. Until recently, the only way to study these two systems and how they interact has been with the use of in vivo preparations. Major advances have been made with acute brain slices containing the thalamocortical and cortico-thalamic pathways in the somatosensory, visual, and auditory systems. With key refinements to our recent modification of the auditory thalamocortical slice(1), we are able to more reliably capture the projections between most of the major auditory midbrain and forebrain structures: the inferior colliculus (IC), medial geniculate body (MGB), thalamic reticular nucleus (TRN), and the auditory cortex (AC). With portions of all these connections retained, we are able to answer detailed questions that complement the questions that can be answered with in vivo preparations. The use of flavoprotein autofluorescence imaging enables us to rapidly assess connectivity in any given slice and guide the ensuing experiment. Using this slice in conjunction with recording and imaging techniques, we are now better equipped to understand how information processing occurs at each point in the auditory forebrain as information ascends to the cortex, and the impact of descending cortical modulation. 3-D printing to build slice chamber components permits double-sided perfusion and broad access to networks within the slice and maintains the widespread connections key to fully utilizing this preparation. PMID:26437382

  8. Computer Simulation of Stress-Strain State of Pipeline Section Affected by Abrasion Due to Mechanical Impurities

    NASA Astrophysics Data System (ADS)

    Burkov, P. V.; Afanas’ev, R. G.; Burkova, S. P.

    2016-04-01

    The paper presents the effect of abrasive wear of the pipeline section occurred due to mechanical impurities in the transported gas flow. The approaches to the detection of the maximum specific wear of the pipeline wall and the geometry of abrasion are the main problems of computer simulation described in this paper.

  9. Preparation of Fe-doped colloidal SiO(2) abrasives and their chemical mechanical polishing behavior on sapphire substrates.

    PubMed

    Lei, Hong; Gu, Qian; Chen, Ruling; Wang, Zhanyong

    2015-08-20

    Abrasives are one of key influencing factors on surface quality during chemical mechanical polishing (CMP). Silica sol, a widely used abrasive in CMP slurries for sapphire substrates, often causes lower material removal rate (MRRs). In the present paper, Fe-doped colloidal SiO2 composite abrasives were prepared by a seed-induced growth method in order to improve the MRR of sapphire substrates. The CMP performance of Fe-doped colloidal SiO2 abrasives on sapphire substrates was investigated using UNIPOL-1502 CMP equipment. Experimental results indicate that the Fe-doped colloidal SiO2 composite abrasives exhibit lower surface roughness and higher MRR than pure colloidal SiO2 abrasives for sapphire substrates under the same testing conditions. Furthermore, the acting mechanism of Fe-doped colloidal SiO2 composite abrasives in sapphire CMP was analyzed by x-ray photoelectron spectroscopy. Analytical results show that the Fe in the composite abrasives can react with the sapphire substrates to form aluminum ferrite (AlFeO3) during CMP, which promotes the chemical effect in CMP and leads to improvement of MRR. PMID:26368752

  10. Development of a two-body wet abrasion test method with attention to the effects of reused abradant

    SciTech Connect

    Blau, Peter Julian; Dehoff, Ryan R

    2012-01-01

    Abrasive wear is among the most common and costliest causes for material wastage, and it occurs in many forms. A simple method has been developed to quantify the response of metals and alloys to two-body wet abrasion. A metallographic polishing machine was modified to create a disk-on-flat sliding test rig. Adhesive-backed SiC grinding papers were used under fixed load and speed to rank the abrasive wear of seven alloy steels, some of which are candidates for drill cones for geothermal drilling. Standardized two-body abrasion tests, like those described in ASTM G132, feed unused abrasive into the contact; however, the current work investigated whether useful rankings could still be obtained with a simpler testing configuration in which specimens repeatedly slide on the same wear path under water-lubricated conditions. Tests using abrasive grit sizes of 120 and 180 resulted in the same relative ranking of the alloys although the coarser grit produced more total wear. Wear decreased when the same abrasive disk was re-used for up to five runs, but the relative rankings of the steels remained the same. This procedure was presented to ASTM Committee G2 on Wear and Erosion as a potential standard test for wet two-body abrasive wear.

  11. Regioselective Biolistic Targeting in Organotypic Brain Slices Using a Modified Gene Gun

    PubMed Central

    Arsenault, Jason; Nagy, Andras; Henderson, Jeffrey T.; O'Brien, John A.

    2014-01-01

    Transfection of DNA has been invaluable for biological sciences and with recent advances to organotypic brain slice preparations, the effect of various heterologous genes could thus be investigated easily while maintaining many aspects of in vivo biology. There has been increasing interest to transfect terminally differentiated neurons for which conventional transfection methods have been fraught with difficulties such as low yields and significant losses in viability. Biolistic transfection can circumvent many of these difficulties yet only recently has this technique been modified so that it is amenable for use in mammalian tissues. New modifications to the accelerator chamber have enhanced the gene gun's firing accuracy and increased its depths of penetration while also allowing the use of lower gas pressure (50 psi) without loss of transfection efficiency as well as permitting a focused regioselective spread of the particles to within 3 mm. In addition, this technique is straight forward and faster to perform than tedious microinjections. Both transient and stable expression are possible with nanoparticle bombardment where episomal expression can be detected within 24 hr and the cell survival was shown to be better than, or at least equal to, conventional methods. This technique has however one crucial advantage: it permits the transfection to be localized within a single restrained radius thus enabling the user to anatomically isolate the heterologous gene's effects. Here we present an in-depth protocol to prepare viable adult organotypic slices and submit them to regioselective transfection using an improved gene gun. PMID:25407047

  12. Verification of Software Product Lines with Delta-Oriented Slicing

    NASA Astrophysics Data System (ADS)

    Bruns, Daniel; Klebanov, Vladimir; Schaefer, Ina

    Software product line (SPL) engineering is a well-known approach to develop industry-size adaptable software systems. SPL are often used in domains where high-quality software is desirable; the overwhelming product diversity, however, remains a challenge for assuring correctness. In this paper, we present delta-oriented slicing, an approach to reduce the deductive verification effort across an SPL where individual products are Java programs and their relations are described by deltas. On the specification side, we extend the delta language to deal with formal specifications. On the verification side, we combine proof slicing and similarity-guided proof reuse to ease the verification process.

  13. ESPRESSO APSU: simplify the life of pupil slicing

    NASA Astrophysics Data System (ADS)

    Conconi, P.; Riva, M.; Pepe, F.; Zerbi, F. M.; Cabral, A.; Cristiani, S.; Megevand, D.; Landoni, M.; Spanó, P.

    2013-09-01

    This paper presents the Espresso Anamorphic pupil Slicer (APSU) implementation. ESPRESSO, the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will be installed on ESOs Very Large Telescope (VLT). In this work we will present the design and trade-off for the pupil slicing system introduced in order to increase the resolving power, effectively decreasing slit width. Its based onto simplified optical component that introduce large anamorphism while keeping low aberrations by means of cylindrical optics. We describe here the trade-off between slicing through two adjacent squared doublets and two achromatic prisms.

  14. Classification of CT-brain slices based on local histograms

    NASA Astrophysics Data System (ADS)

    Avrunin, Oleg G.; Tymkovych, Maksym Y.; Pavlov, Sergii V.; Timchik, Sergii V.; Kisała, Piotr; Orakbaev, Yerbol

    2015-12-01

    Neurosurgical intervention is a very complicated process. Modern operating procedures based on data such as CT, MRI, etc. Automated analysis of these data is an important task for researchers. Some modern methods of brain-slice segmentation use additional data to process these images. Classification can be used to obtain this information. To classify the CT images of the brain, we suggest using local histogram and features extracted from them. The paper shows the process of feature extraction and classification CT-slices of the brain. The process of feature extraction is specialized for axial cross-section of the brain. The work can be applied to medical neurosurgical systems.

  15. A critical review of non-carious cervical (wear) lesions and the role of abfraction, erosion, and abrasion.

    PubMed

    Bartlett, D W; Shah, P

    2006-04-01

    The terms 'abfraction' and 'abrasion' describe the cause of lesions found along the cervical margins of teeth. Erosion, abrasion, and attrition have all been associated with their formation. Early research suggested that the cause of the V-shaped lesion was excessive horizontal toothbrushing. Abfraction is another possible etiology and involves occlusal stress, producing cervical cracks that predispose the surface to erosion and abrasion. This article critically reviews the literature on abrasion, erosion, and abrasion, and abfraction. The references were obtained by a MEDLINE search in March, 2005, and from this, hand searches were undertaken. From the literature, there is little evidence, apart from laboratory studies, to indicate that abfraction exists other than as a hypothetical component of cervical wear. PMID:16567549

  16. Climate variability around the first Pliocene time slice

    NASA Astrophysics Data System (ADS)

    Prescott, C.; Haywood, A.; Dolan, A. M.; Hunter, S. J.; Tindall, J.; Pope, J. O.; Pickering, S.

    2013-12-01

    Existing data/model comparisons for the mid-Pliocene (Dowsett et al., 2013) have identified specific regions of concordance and discord between climate models and proxy data. One reason for site-specific disagreement is likely related to the time (warm peak) averaged nature of the mid-Pliocene ocean temperatures provided within existing proxy syntheses. To facilitate improved data/model comparisons in the future new proxy sea surface temperature reconstructions will focus on specific time slices within the Pliocene epoch. Haywood et al. (2013) identified an initial time slice for environmental reconstruction and climate modelling centred on an interglacial event at Marine Isotope Stage KM5c (3.205 Ma). Critically, this interval displays a very near to modern orbital configuration simplifying the interpretation of proxy data and the experimental design for climate models. Nevertheless, current limitations of chronology and correlation make it likely that new proxy records will be attributable to a time range around the time slice, and may not always represent the time slice specifically. This introduces an element of uncertainty through orbital forcing around the time slice which can be investigated and quantified within a numerical climate modelling framework. The Hadley Centre Coupled Climate Model Version 3 (HadCM3) has been used to perform a series of orbital forcing sensitivity tests around the identified time slice at MIS KM5c. Simulations every 2 kyr either side of the time slice to a range +/- 20 kyr have been completed. The model results indicate that +/- 20 kyr either side of the time slice, orbital forcing generates a less than 1°C change on global MAT. One exception to this relative stability in climate is seen in the North Atlantic (a region noted for disagreement in existing Pliocene data/model comparisons). Here, ocean surface temperature variations of up to 6°C are predicted. These model responses appear to be linked to changes in ocean circulation

  17. Regulation of Axolotl (Ambystoma mexicanum) Limb Blastema Cell Proliferation by Nerves and BMP2 in Organotypic Slice Culture

    PubMed Central

    Lehrberg, Jeffrey; Gardiner, David M.

    2015-01-01

    We have modified and optimized the technique of organotypic slice culture in order to study the mechanisms regulating growth and pattern formation in regenerating axolotl limb blastemas. Blastema cells maintain many of the behaviors that are characteristic of blastemas in vivo when cultured as slices in vitro, including rates of proliferation that are comparable to what has been reported in vivo. Because the blastema slices can be cultured in basal medium without fetal bovine serum, it was possible to test the response of blastema cells to signaling molecules present in serum, as well as those produced by nerves. We also were able to investigate the response of blastema cells to experimentally regulated changes in BMP signaling. Blastema cells responded to all of these signals by increasing the rate of proliferation and the level of expression of the blastema marker gene, Prrx-1. The organotypic slice culture model provides the opportunity to identify and characterize the spatial and temporal co-regulation of pathways in order to induce and enhance a regenerative response. PMID:25923915

  18. Regulation of Axolotl (Ambystoma mexicanum) Limb Blastema Cell Proliferation by Nerves and BMP2 in Organotypic Slice Culture.

    PubMed

    Lehrberg, Jeffrey; Gardiner, David M

    2015-01-01

    We have modified and optimized the technique of organotypic slice culture in order to study the mechanisms regulating growth and pattern formation in regenerating axolotl limb blastemas. Blastema cells maintain many of the behaviors that are characteristic of blastemas in vivo when cultured as slices in vitro, including rates of proliferation that are comparable to what has been reported in vivo. Because the blastema slices can be cultured in basal medium without fetal bovine serum, it was possible to test the response of blastema cells to signaling molecules present in serum, as well as those produced by nerves. We also were able to investigate the response of blastema cells to experimentally regulated changes in BMP signaling. Blastema cells responded to all of these signals by increasing the rate of proliferation and the level of expression of the blastema marker gene, Prrx-1. The organotypic slice culture model provides the opportunity to identify and characterize the spatial and temporal co-regulation of pathways in order to induce and enhance a regenerative response. PMID:25923915

  19. beta. -adrenergic ((/sup 3/H) CGP-12177) receptors are elevated in slices of soleus muscle from CHF 147 dystrophic hamsters

    SciTech Connect

    Watson-Wright, W.M.; Wilkinson, M.

    1987-03-23

    The authors utilized a muscle slice technique to compare the ontogeny of cell surface ..beta..-adrenergic receptor binding in soleus and extensor digitorum longus (EDL) muscles of male Golden Syrian (GS) and Canadian Hybrid Farms 147 (CHF 147) dystrophic hamsters. Binding of the ..beta..-adrenergic antagonist, (/sup 3/H) CGP-12177 (CGP), to GS muscle slices was reversible, saturable, stereospecific and of high affinity. Bmax was higher in the soleus (2.57+/-.12 fmol/mg wet wt) than in the EDL (1.61+/-.17 fmol/mg wet wt) of adult animals while affinities were similar (0.35+/-.06 and 0.24+/-.04 nM respectively). No differences in binding characteristics were seen in EDL of GS compared to CHF 147 animals. In soleus slices from GS hamsters, Bmax was highest at 16 days of age (5.72+/-0.26 fmol/mg), decreased between 16 and 29 days and remained constant until 300 days (2.51+/-0.52 fmol/mg). In dystrophic soleus slices, Bmax was also higher at 16 days than at any other age but receptor number decreased gradually, remaining higher than in GS until 90 days of age (p<0.05). The failure of ..beta..-adrenergic receptor number to decrease at a normal rate may be implicated in the pathogenesis of hamster polymyopathy. 21 references, 5 figures, 1 table.

  20. A review on nozzle wear in abrasive water jet machining application

    NASA Astrophysics Data System (ADS)

    Syazwani, H.; Mebrahitom, G.; Azmir, A.

    2016-02-01

    This paper discusses a review on nozzle wear in abrasive water jet machining application. Wear of the nozzle becomes a major problem since it may affect the water jet machining performance. Design, materials, and life of the nozzle give significance effect to the nozzle wear. There are various parameters that may influence the wear rate of the nozzle such as nozzle length, nozzle inlet angle, nozzle diameter, orifice diameter, abrasive flow rate and water pressure. The wear rate of the nozzle can be minimized by controlling these parameters. The mechanism of wear in the nozzle is similar to other traditional machining processes which uses a cutting tool. The high pressure of the water and hard abrasive particles may erode the nozzle wall. A new nozzle using a tungsten carbide-based material has been developed to reduce the wear rate and improve the nozzle life. Apart from that, prevention of the nozzle wear has been achieved using porous lubricated nozzle. This paper presents a comprehensive review about the wear of abrasive water jet nozzle.

  1. Tribological properties of amorphous alloys and the role of surfaces in abrasive wear of materials

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1982-01-01

    The research approach undertaken by the authors relative to the subject, and examples of results from the authors are reviewed. The studies include programs in adhesion, friction, and various wear mechanisms (adhesive and abrasive wear). The materials which have been studied include such ceramic and metallic materials as silicon carbide, ferrites, diamond, and amorphous alloys.

  2. 16 CFR Figure 8 to Part 1512 - Reflectorized Bicycle Wheel Rim Abrasion Test Device

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Reflectorized Bicycle Wheel Rim Abrasion Test Device 8 Figure 8 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 8 Figure 8 to Part...

  3. 16 CFR Figure 8 to Part 1512 - Reflectorized Bicycle Wheel Rim Abrasion Test Device

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Reflectorized Bicycle Wheel Rim Abrasion Test Device 8 Figure 8 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 8 Figure 8 to Part...

  4. 16 CFR Figure 8 to Part 1512 - Reflectorized Bicycle Wheel Rim Abrasion Test Device

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Reflectorized Bicycle Wheel Rim Abrasion Test Device 8 Figure 8 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 8 Figure 8 to Part...

  5. 16 CFR Figure 8 to Part 1512 - Reflectorized Bicycle Wheel Rim Abrasion Test Device

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Reflectorized Bicycle Wheel Rim Abrasion Test Device 8 Figure 8 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 8 Figure 8 to Part...

  6. 16 CFR Figure 8 to Part 1512 - Reflectorized Bicycle Wheel Rim Abrasion Test Device

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Reflectorized Bicycle Wheel Rim Abrasion Test Device 8 Figure 8 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 8 Figure 8 to Part...

  7. Microstructural effects in abrasive wear. Quarterly progress report, January 1-June 1, 1980

    SciTech Connect

    Fiore, N.F.; Kosel, T.H.; Channagiri, M.; Desai, V.; Fulcher, J.; Shetty, H.R.

    1980-06-01

    Research aimed at establishing quantitative relationships between microstructure and wear resistance of highly alloyed materials is described including high-Cr white irons and experimental Co-base and Ni-base powder metallurgy (PM) alloys now used or potentially to be used in coal mining, handling and gasification. The specific types of wear under study are low-stress abrasion and gouging wear encountered in mining, coal conversion and transfer applications. Research has concentrated on the investigation of wear in Co-base PM alloys No. 19 and No. 6, which have been sintered to provide different carbide sizes at the same volume fraction in each respective alloy. Low-stress abrasion tests using Al/sub 2/O/sub 3/ abrasive have been completed on Alloy No. 19 and the results show a monotonic decrease in wear rate with increasing size. A series of single-point scratch test simulations of abrasive wear mechanisms has been initiated, and these tests provide valuable insights into material removal processes in the Co-base alloys.

  8. Optical tools for high-throughput screening of abrasion resistance of combinatorial libraries of organic coatings

    NASA Astrophysics Data System (ADS)

    Potyrailo, Radislav A.; Chisholm, Bret J.; Olson, Daniel R.; Brennan, Michael J.; Molaison, Chris A.

    2002-02-01

    Design, validation, and implementation of an optical spectroscopic system for high-throughput analysis of combinatorially developed protective organic coatings are reported. Our approach replaces labor-intensive coating evaluation steps with an automated system that rapidly analyzes 8x6 arrays of coating elements that are deposited on a plastic substrate. Each coating element of the library is 10 mm in diameter and 2 to 5 micrometers thick. Performance of coatings is evaluated with respect to their resistance to wear abrasion because this parameter is one of the primary considerations in end-use applications. Upon testing, the organic coatings undergo changes that are impossible to quantitatively predict using existing knowledge. Coatings are abraded using industry-accepted abrasion test methods at single-or multiple-abrasion conditions, followed by high- throughput analysis of abrasion-induced light scatter. The developed automated system is optimized for the analysis of diffusively scattered light that corresponds to 0 to 30% haze. System precision of 0.1 to 2.5% relative standard deviation provides capability for the reliable ranking of coatings performance. While the system was implemented for high-throughput screening of combinatorially developed organic protective coatings for automotive applications, it can be applied to a variety of other applications where materials ranking can be achieved using optical spectroscopic tools.

  9. Parametric Study to Correlate the Applied Factors and Abrasive Wear Resistance of HVOF Coating

    NASA Astrophysics Data System (ADS)

    Sharma, Satpal

    2012-12-01

    Co-Ni-base powder was modified with the addition of CeO2 to study the effect of CeO2 addition on microstructure, hardness, and abrasive wear behavior of the unmodified (without CeO2) and modified (with CeO2) HVOF sprayed coatings. To investigate the abrasive wear behavior of coatings statistical response surface methodology (RSM) with four factors such as load, abrasive size, sliding distance, and temperature with three levels of each factor were used. Analysis of variance (ANOVA) was carried out to determine the significant factors and their interactions. Thus abrasive wear model was developed in terms of main factors and their significant interactions. The validity of the model was evaluated by conducting experiments under different wear conditions. A comparison of modeled and experimental results showed 2-8% error. The wear resistance of coatings increased with the addition of CeO2. This is due to increase in hardness with the addition of CeO2 in Co-Ni-base coatings.

  10. Sand abrasion injury and plant survival in cotton seedlings of different ages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of hectares of crops are exposed to wind-blown soil abrasion injury each year and in many instances the damage is severe enough to require replanting. Little attention has been given to plant physiological or morphological factors that may lend resistance to, or enhance recovery from, wind-...

  11. ICAM-1 mediates surface contact between neutrophils and keratocytes following corneal epithelial abrasion in the mouse

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corneal epithelial abrasion elicits an inflammatory response involving neutrophil (PMN) recruitment from the limbal vessels into the corneal stroma. These migrating PMNs make surface contact with collagen and stromal keratocytes. Using mice deficient in PMN integrin CD18, we previously showed that P...

  12. NK cells modulate the inflammatory response to corneal epithelial abrasion and thereby support wound healing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural killer cells are lymphocytes of the innate immune system that have crucial cytotoxic and regulatory roles in adaptive immunity and inflammation. Herein, we consider a role for these cells in corneal wound healing. After a 2-mm central epithelial abrasion of the mouse cornea, a subset of clas...

  13. Intraoral leukoplakia, abrasion, periodontal breakdown, and tooth loss in a snuff dipper.

    PubMed

    Christen, A G; Armstrong, W R; McDaniel, R K

    1979-04-01

    Dentists should be aware that snuff dipping or chewing is increasing in southern states and perhaps in other sections of the United States. These habits can lead to clinical leukoplakia, gingival recession, tooth abrasion, and periodontal bone destruction. The possibility also exists that a malignant transformation of leukoplakia can develop in persons who use snuff and other forms of tobacco. PMID:285136

  14. Abrasive wear behavior of heat-treated ABC-silicon carbide

    SciTech Connect

    Zhang, Xiao Feng; Lee, Gun Y.; Chen, Da; Ritchie, Robert O.; De Jonghe, Lutgard C.

    2002-06-17

    Hot-pressed silicon carbide, containing aluminum, boron, and carbon additives (ABC-SiC), was subjected to three-body and two-body wear testing using diamond abrasives over a range of sizes. In general, the wear resistance of ABC-SiC, with suitable heat treatment, was superior to that of commercial SiC.

  15. Investigation of abrasion in Al–MgO metal matrix composites

    SciTech Connect

    Muharr em Pul; Çalin, Recep; Gül, Ferhat

    2014-12-15

    In this study, the effects of reinforcement volume fractions on abrasive wear behavior were examined in Al–MgO reinforced metal matrix composites of 5%, 10% and 15% reinforcement – volume ratios produced by melt-stirring. Abrasive wear tests were carried out by 60, 80 and 100 mesh sized Al{sub 2}O{sub 3} abrasive papers and pin-on-disc wear test apparatus under 10, 20 and 30 N loads at 0.2 m/s sliding speed. The mechanical properties such as hardness and fracture strength were determined. Subsequent to the wear tests, the microstructures of worn surfaces were examined by scanning electron microscope analyses. While increased MgO reinforcement volume fraction in the composite resulted increased hardness, fracture strength was determined to decrease. Additionally, it was found that increased MgO reinforcement volume fraction in the composite was accompanied with increased wear loss and porosity as well as reinforcement – volume ratio was identified to be significant determinants of abrasive wear behavior.

  16. PAGMan - propelled abrasive grit to manage weeds in soybean and corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New tools for controlling weeds would be useful for soybean and corn production in organic systems or in systems in which weeds developed resistance to multiple herbicides. Here we report on two developments: (i) the safety to soybean seedlings of using air-propelled abrasive grit (PAG) for managing...

  17. Characterization of abrasion-induced nanoparticle release from paints into liquids and air

    NASA Astrophysics Data System (ADS)

    Golanski, L.; Gaborieau, A.; Guiot, A.; Uzu, G.; Chatenet, J.; Tardif, F.

    2011-07-01

    Two standard methods for the characterization of the abrasion nanoparticle release into air and liquid from coatings containing nanoparticles were developed. Details of the abrasion processes and the measurement methods are shown. Paints were formulated in an industrial facility. Standard abrasion conditions in wet environments were simulated. The size distribution of the particles abraded into liquid was analyzed by a laser granulometer: submicrometric and micrometric particles were observed, but no nanometric particles. The nanoparticles released in liquid were deposited on filters for SEM (Scanning Electron Microscopy) analysis. No free or agglomerated nanoparticles were observed by SEM: nanoparticles seem to remain embedded in the paint matrix. The same coatings were abraded in the air using another standard method. The ELPI (Electrical Low Pressure Impactor) was used to determine the number size distribution of the dust generated. Abrasion is found to produce submicrometric and micrometric particles in the air but no nanoparticles. Further characterizations by SEM confirmed that no free or agglomerated nanoparticles were emitted: nanoparticles seem to remain embedded in the paint matrix.

  18. Two waves of neutrophil emigration in response to corneal epithelial abrasion: Distinct adhesion molecule requirements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    PURPOSE: Corneal abrasion results in an inflammatory response characterized by leukocyte emigration into the corneal stroma. Adhesion molecules play a critical role in leukocyte emigration to wound sites, but differences are evident in different vascular beds. In this study, the contributions of two...

  19. Laser abrasion for cosmetic and medical treatment of facial actinic damage

    SciTech Connect

    David, L.M.; Lask, G.P.; Glassberg, E.; Jacoby, R.; Abergel, R.P.

    1989-06-01

    Previous studies have shown the carbon dioxide (CO/sub 2/) laser to be effective in the treatment of actinic cheilitis. After CO/sub 2/ laser abrasion, normal skin and marked cosmetic improvement of the lip were noted. In our study, twenty-three patients were treated with CO/sub 2/ laser abrasions for cosmetic improvement of facial lines and actinic changes. Pre- and postoperative histopathologic examinations were made on two patients. Preoperative examination of specimens from actinically damaged skin showed atypical keratinocytes in the basal layer of the epidermis, with overlying dense compact orthokeratosis and parakeratosis. Abundant solar elastosis was seen in the papillary dermis. Postoperative histologic specimens showed a normal-appearing epidermis with fibrosis in the papillary dermis and minimal solar elastosis (about four weeks after laser treatment). At present, various modalities are available for the regeneration of the aged skin, including chemical peels and dermabrasion. Significantly fewer complications were noted with CO/sub 2/ laser abrasion than with these methods. Thus, CO/sub 2/ laser abrasion can be useful in the cosmetic and medical treatment of the aged skin. Marked clinical and histologic improvement has been demonstrated.

  20. Platelet recruitment promotes keratocyte repopulation following corneal epithelial abrasion in the mouse

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corneal abrasion not only damages the epithelium but also induces stromal keratocyte death at the site of injury. While a coordinated cascade of inflammatory cell recruitment facilitates epithelial restoration, it is unclear if this cascade is necessary for keratocyte recovery. Since platelet and ne...

  1. Platelet response to corneal abrasion is necessary for acute inflammation and efficient re-epithelialization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Purpose: Adhesion molecules play a critical role in leukocyte emigration to wound sites, but differences are evident in different vascular beds. This study investigates the contributions of P-selectin to neutrophil emigration into the cornea following central epithelial abrasion. Methods: Re-epithel...

  2. Martian and Terrestrial Rock Abrasion from Wind Tunnel and Field Studies

    NASA Technical Reports Server (NTRS)

    Bridges, N. T.; Greeley, R.; Eddlemon, E.; Laity, J. E.; Meyer, C.; Phoreman, J.; White, B. R.

    2003-01-01

    Earth and Mars exhibit ventifacts, rocks that have been abraded by saltating sand. Previous theoretical and laboratory studies have determined abrasion susceptibilities of rocks as a function of sand type and impact angle and rock material strengths. For the last two years we have been engaged in wind tunnel and field studies to better understand the fundamental factors which control and influence rock abrasion and ventifact formation on Earth and Mars. In particular, we are examining: 1) What types of rocks (composition, texture, and shape) preferentially erode and what are the relative rates of one type vs. another? 2) What are the controlling factors of the aeolian sand cloud (flux, particle speed, surface roughness, etc) which favor rock abrasion?, 3) How do specific ventifact characteristics tie into their mode of formation and rock properties? We find several important factors: 1) Initial rock shape controls the rate of abrasion, with steeper faces abrading faster than shallower ones. The relationship is partly dependent on angle-dependent flux (proportional to sin[theta]) but exhibits additional non-linear effects from momentum transfer efficiency and rebound effects that vary with incidence angle. 2) Irregular targets with pits or grooves abrade at greater rates than targets with smooth surfaces, with indentations generally enlarging with time. Surfaces become rougher with time. 3) Targets also abrade via slope retreat, which is roughly dependent on the slope of the front face. The formation of basal sills is common, as observed on terrestrial and Martian ventifacts.

  3. LSA Large Area Silicon Sheet Task Enhanced I.D. Slicing Technology for Silicon Ingots

    NASA Technical Reports Server (NTRS)

    Walters, D.

    1979-01-01

    Development of inside diameter slicing technology to significantly increase the number of useable slices per inch of crystal over industry practice is discussed. The required reduction of both blade and slice thickness is to be accomplished by a combination of three key elements of slicing technology: (1) ingot rotation with minimum exposed blade area; (2) dynamic cutting edge control; and (3) the use of prefabricated insert blades. Design modifications on a slicing saw with microprocessor controls and hardware fabrication to complete this conversion were initiated. Several runs were conducted on the engineering saw incorporating the method of ingot rotation. Ingots with diameters up to six inches were sliced successfully on a production saw.

  4. From synchrotron radiation to lab source: advanced speckle-based X-ray imaging using abrasive paper

    PubMed Central

    Wang, Hongchang; Kashyap, Yogesh; Sawhney, Kawal

    2016-01-01

    X-ray phase and dark-field imaging techniques provide complementary and inaccessible information compared to conventional X-ray absorption or visible light imaging. However, such methods typically require sophisticated experimental apparatus or X-ray beams with specific properties. Recently, an X-ray speckle-based technique has shown great potential for X-ray phase and dark-field imaging using a simple experimental arrangement. However, it still suffers from either poor resolution or the time consuming process of collecting a large number of images. To overcome these limitations, in this report we demonstrate that absorption, dark-field, phase contrast, and two orthogonal differential phase contrast images can simultaneously be generated by scanning a piece of abrasive paper in only one direction. We propose a novel theoretical approach to quantitatively extract the above five images by utilising the remarkable properties of speckles. Importantly, the technique has been extended from a synchrotron light source to utilise a lab-based microfocus X-ray source and flat panel detector. Removing the need to raster the optics in two directions significantly reduces the acquisition time and absorbed dose, which can be of vital importance for many biological samples. This new imaging method could potentially provide a breakthrough for numerous practical imaging applications in biomedical research and materials science. PMID:26847921

  5. From synchrotron radiation to lab source: advanced speckle-based X-ray imaging using abrasive paper

    NASA Astrophysics Data System (ADS)

    Wang, Hongchang; Kashyap, Yogesh; Sawhney, Kawal

    2016-02-01

    X-ray phase and dark-field imaging techniques provide complementary and inaccessible information compared to conventional X-ray absorption or visible light imaging. However, such methods typically require sophisticated experimental apparatus or X-ray beams with specific properties. Recently, an X-ray speckle-based technique has shown great potential for X-ray phase and dark-field imaging using a simple experimental arrangement. However, it still suffers from either poor resolution or the time consuming process of collecting a large number of images. To overcome these limitations, in this report we demonstrate that absorption, dark-field, phase contrast, and two orthogonal differential phase contrast images can simultaneously be generated by scanning a piece of abrasive paper in only one direction. We propose a novel theoretical approach to quantitatively extract the above five images by utilising the remarkable properties of speckles. Importantly, the technique has been extended from a synchrotron light source to utilise a lab-based microfocus X-ray source and flat panel detector. Removing the need to raster the optics in two directions significantly reduces the acquisition time and absorbed dose, which can be of vital importance for many biological samples. This new imaging method could potentially provide a breakthrough for numerous practical imaging applications in biomedical research and materials science.

  6. Characterization of masses in digital breast tomosynthesis: Comparison of machine learning in projection views and reconstructed slices

    SciTech Connect

    Chan, Heang-Ping; Wu Yita; Sahiner, Berkman; Wei, Jun; Helvie, Mark A.; Zhang Yiheng; Moore, Richard H.; Kopans, Daniel B.; Hadjiiski, Lubomir; Way, Ted

    2010-07-15

    Purpose: In digital breast tomosynthesis (DBT), quasi-three-dimensional (3D) structural information is reconstructed from a small number of 2D projection view (PV) mammograms acquired over a limited angular range. The authors developed preliminary computer-aided diagnosis (CADx) methods for classification of malignant and benign masses and compared the effectiveness of analyzing lesion characteristics in the reconstructed DBT slices and in the PVs. Methods: A data set of MLO view DBT of 99 patients containing 107 masses (56 malignant and 51 benign) was collected at the Massachusetts General Hospital with IRB approval. The DBTs were obtained with a GE prototype system which acquired 11 PVs over a 50 deg. arc. The authors reconstructed the DBTs at 1 mm slice interval using a simultaneous algebraic reconstruction technique. The region of interest (ROI) containing the mass was marked by a radiologist in the DBT volume and the corresponding ROIs on the PVs were derived based on the imaging geometry. The subsequent processes were fully automated. For classification of masses using the DBT-slice approach, the mass on each slice was segmented by an active contour model initialized with adaptive k-means clustering. A spiculation likelihood map was generated by analysis of the gradient directions around the mass margin and spiculation features were extracted from the map. The rubber band straightening transform (RBST) was applied to a band of pixels around the segmented mass boundary. The RBST image was enhanced by Sobel filtering in the horizontal and vertical directions, from which run-length statistics texture features were extracted. Morphological features including those from the normalized radial length were designed to describe the mass shape. A feature space composed of the spiculation features, texture features, and morphological features extracted from the central slice alone and seven feature spaces obtained by averaging the corresponding features from three to 19

  7. The Effect of Pleural Abrasion on the Treatment of Primary Spontaneous Pneumothorax: A Systematic Review of Randomized Controlled Trials

    PubMed Central

    Ming, Mo-yu; Cai, Shuang-qi; Chen, Yi-Qiang

    2015-01-01

    Background Pleural abrasion has been widely used to control the recurrence of primary spontaneous pneumothorax (PSP). However, controversy still exists regarding the advantages and disadvantages of pleural abrasion compared with other interventions in preventing the recurrence of PSP. Methods The PubMed, Embase, and Cochrane Central Register of Controlled Trials databases were searched up to December 15, 2014 to identify randomized controlled trials (RCTs) that compared the effects of pleural abrasion with those of other interventions in the treatment of PSP. The study outcomes included the PSP recurrence rate and the occurrence rate of adverse effects. Results Mechanical pleural abrasion and apical pleurectomy after thoracoscopic stapled bullectomy exhibited similarly persistent postoperative air leak occurrence rates (p = 0.978) and 1-year PSP recurrence rates (p = 0.821), whereas pleural abrasion led to reduced residual chest pain and discomfort (p = 0.001) and a smaller rate of hemothorax (p = 0.036) than did apical pleurectomy. However, the addition of minocycline pleurodesis to pleural abrasion did not reduce the pneumothorax recurrence rate compared with apical pleurectomy (3.8% for both procedures) but was associated with fewer complications. There was no statistical difference in the pneumothorax recurrence rate between mechanical pleural abrasion and chemical pleurodesis with minocycline on either an intention-to-treat basis (4 of 42 versus 0 of 42, p = 0.12; Fisher exact test) or after exclusions (2 of 40 versus 0 of 42, p = 0.24; Fisher exact test). Pleural abrasion plus minocycline pleurodesis also did not reduce the pneumothorax recurrence rate compared with pleural abrasion alone (p = 0.055). Moreover, pleural abrasion plus minocycline pleurodesis was associated with more intense acute chest pain. The postoperative overall recurrence rate in patients who underwent staple line coverage with absorbable cellulose mesh and fibrin glue was similar to that

  8. Forecasting of operational indicators of grinding tools with the controlled form and orientation of abrasive grains

    NASA Astrophysics Data System (ADS)

    Korotkov, V. A.; Minkin, E. M.

    2015-09-01

    The interconnection of the abrasive grain front angle parameter with the form, orientation and wear out parameters is investigated. The form of the abrasive grains was estimated by means of form coefficient which represents the relation of diameters of the spheres described around contours of grains, to diameters of the spheres entered in them. The spatial orientation angle of the abrasive grains was defined between main (i.e. the biggest) axis of the grains and the cutting plane. It is established that, depending on an orientation angle at increase in a form coefficient of the abrasive grains can be either an increase or a decrease in the values of their front angles. In most cases, with an increase in a form coefficient of the oriented grinding grains (at orientation angles Θ=10°÷125°) the growth of their front angles is fixed. At tangential orientation of grains (Θ=0°) and at the close directions of orientation (Θ=135°÷80°) the return picture is observed. Also established that the longer the abrasive grain wears along the main axis and located in the tool body, the larger is its front angle. Besides that, the front angles of the abrasive grains reach the maximum positive values at orientation angles Θ=22.5°÷45°.Dependence of tension in grains during the work with parameters of their form, orientation and depth of embedment in the bundle is investigated. It was found that for all orientation angles of grains their tension significantly increases with an increase in their form coefficient. Besides that it is confirmed that the deeper the grain is in the bundle, the lower the tension is there. Also found that tension is minimal when the grains are tangential orientated. Further on increase the option of the grains in the direction of action of the cutting force follows. Such option of orientation is the most rational both from the point of view of minimization of tension, and for ensuring rational sizes of front angles of the abrasive grains. The

  9. METHOXYCHLOR METABOLISM AND VITELLOGENESIS IN MALE RAINBOW TROUT LIVER SLICES

    EPA Science Inventory

    Induction of vitellogenin (VTG) in male fish has become an accepted biomarker to xenoestrogenicity. This study utilized the male rainbow trout liver slice model to determine the estrogenicity of parent compound, methoxychlor (MXC) and metabolites, di-hydroxy methoxychlor (HPTE) a...

  10. Excitation and geometrically matched local encoding of curved slices.

    PubMed

    Weber, Hans; Gallichan, Daniel; Schultz, Gerrit; Cocosco, Chris A; Littin, Sebastian; Reichardt, Wilfried; Welz, Anna; Witschey, Walter; Hennig, Jürgen; Zaitsev, Maxim

    2013-05-01

    In this work, the concept of excitation and geometrically matched local in-plane encoding of curved slices (ExLoc) is introduced. ExLoc is based on a set of locally near-orthogonal spatial encoding magnetic fields, thus maintaining a local rectangular shape of the individual voxels and avoiding potential problems arising due to highly irregular voxel shapes. Unlike existing methods for exciting curved slices based on multidimensional radiofrequency-pulses, excitation and geometrically matched local encoding of curved slices does not require long duration or computationally expensive radiofrequency-pulses. As each encoding field consists of a superposition of potentially arbitrary (spatially linear or nonlinear) magnetic field components, the resulting field shape can be adapted with high flexibility to the specific region of interest. For extended nonplanar structures, this results in improved relevant volume coverage for fewer excited slices and thus increased efficiency. In addition to the mathematical description for the generation of dedicated encoding fields and data reconstruction, a verification of the ExLoc concept in phantom experiments and examples for in vivo curved single and multislice imaging are presented. PMID:22711656

  11. Mathematical modeling on vacuum drying of Zizyphus jujuba Miller slices.

    PubMed

    Lee, Jun Ho; Zuo, Li

    2013-02-01

    The thin-layer vacuum drying behavior of Zizyphus jujuba Miller slices was experimentally investigated at the temperature of 50, 60, and 70 °C and the mathematical models were used to fit the thin-layer vacuum drying of Z. jujuba slices. The increase in drying air temperature resulted in a decrease in drying time. The drying rate was found to increase with temperature, thereby reducing the total drying time. It was found that Z. jujuba slices with thickness of 4 mm would be dried up to 0.08 kg water/kg dry matter in the range of 180-600 min in the vacuum dryer at the studied temperature range from 70 to 50 °C. The Midilli et al. model was selected as the most appropriate model to describe the thin-layer drying of Z. jujuba slices. The diffusivity coefficient increased linearly over the temperature range from 1.47 × 10(-10) to 3.27 × 10(-10) m(2)/s, as obtained using Fick's second law. The temperature dependence of the effective diffusivity coefficient followed an Arrhenius-type relationship. The activation energy for the moisture diffusion was determined to be 36.76 kJ/mol. PMID:24425895

  12. Blanching, salting and sun drying of different pumpkin fruit slices.

    PubMed

    Workneh, T S; Zinash, A; Woldetsadik, K

    2014-11-01

    The study was aimed at assessing the quality of pumpkin (Cucuribita Spp.) slices that were subjected to pre-drying treatments and drying using two drying methods (uncontrolled sun and oven) fruit accessions. Pre-drying had significant (P ≤ 0.05) effect on the quality of dried pumpkin slices. 10 % salt solution dipped pumpkin fruit slices had good chemical quality. The two-way interaction between drying methods and pre-drying treatments had significant (P ≤ 0.05) effect on chemical qualities. Pumpkin subjected to salt solution dipping treatment and oven dried had higher chemical concentrations. Among the pumpkin fruit accessions, pumpkin accession 8007 had the superior TSS, total sugar and sugar to acid ratio after drying. Among the three pre-drying treatment, salt solution dipping treatment had significant (P ≤ 0.05) effect and the most efficient pre-drying treatment to retain the quality of dried pumpkin fruits without significant chemical quality deterioration. Salt dipping treatment combined with low temperature (60 °C) oven air circulation drying is recommended to maintain quality of dried pumpkin slices. However, since direct sun drying needs extended drying time due to fluctuation in temperature, it is recommended to develop or select best successful solar dryer for use in combination with pre-drying salt dipping or blanching treatments. PMID:26396303

  13. Pyrethroid insecticides evoke neurotransmitter release from rabbit striatal slices

    SciTech Connect

    Eells, J.T.; Dubocovich, M.L.

    1988-08-01

    The effects of the synthetic pyrethroid insecticide fenvalerate ((R,S)-alpha-cyano-3-phenoxybenzyl(R,S)-2-(4-chlorophenyl)-3- methylbutyrate) on neurotransmitter release in rabbit brain slices were investigated. Fenvalerate evoked a calcium-dependent release of (/sup 3/H)dopamine and (/sup 3/H)acetylcholine from rabbit striatal slices that was concentration-dependent and specific for the toxic stereoisomer of the insecticide. The release of (/sup 3/H)dopamine and (/sup 3/H)acetylcholine by fenvalerate was modulated by D2 dopamine receptor activation and antagonized completely by the sodium channel blocker, tetrodotoxin. These findings are consistent with an action of fenvalerate on the voltage-dependent sodium channels of the presynaptic membrane resulting in membrane depolarization, and the release of dopamine and acetylcholine by a calcium-dependent exocytotic process. In contrast to results obtained in striatal slices, fenvalerate did not elicit the release of (/sup 3/H)norepinephrine or (/sup 3/H)acetylcholine from rabbit hippocampal slices indicative of regional differences in sensitivity to type II pyrethroid actions.

  14. Gingival abrasion and recession in manual and oscillating–rotating power brush users

    PubMed Central

    Rosema, NAM; Adam, R; Grender, JM; Van der Sluijs, E; Supranoto, SC; Van der Weijden, GA

    2014-01-01

    Objective To assess gingival recession (GR) in manual and power toothbrush users and evaluate the relationship between GR and gingival abrasion scores (GA). Methods This was an observational (cross-sectional), single-centre, examiner-blind study involving a single-brushing exercise, with 181 young adult participants: 90 manual brush users and 91 oscillating–rotating power brush users. Participants were assessed for GR and GA as primary response variables. Secondary response variables were the level of gingival inflammation, plaque score reduction and brushing duration. Pearson correlation was used to describe the relationship between number of recession sites and number of abrasions. Prebrushing (baseline) and post-brushing GA and plaque scores were assessed and differences analysed using paired tests. Two-sample t-test was used to analyse group differences; ancova was used for analyses of post-brushing changes with baseline as covariate. Results Overall, 97.8% of the study population had at least one site of ≥1 mm of gingival recession. For the manual group, this percentage was 98.9%, and for the power group, this percentage was 96.7% (P = 0.621). Post-brushing, the power group showed a significantly smaller GA increase than the manual group (P = 0.004); however, there was no significant correlation between number of recession sites and number of abrasions for either group (P ≥ 0.327). Conclusions Little gingival recession was observed in either toothbrush user group; the observed GR levels were comparable. Lower post-brushing gingival abrasion levels were seen in the power group. There was no correlation between gingival abrasion as a result of brushing and the observed gingival recession following use of either toothbrush. PMID:24871587

  15. Glacial erosion and bedrock properties in NW Scotland: Abrasion and plucking, hardness and joint spacing

    NASA Astrophysics Data System (ADS)

    Krabbendam, Maarten; Glasser, Neil F.

    2011-07-01

    Subglacial erosion beneath glaciers occurs predominantly by abrasion and plucking, producing distinct erosional forms. The controls on the relative importance of abrasion vs. plucking are poorly understood. On the one hand, glacial conditions that favour or suppress cavity formation (ice velocity, ice thickness, and water pressure) are thought to favour plucking or abrasion, respectively. Conversely, bedrock properties are also known to control landforms, but this has rarely been analysed quantitatively. In this study we compare landforms and bedrock properties of sandstone and quartzite at the bed of a palaeo-ice stream near Ullapool in NW Scotland. The boundary between the rock types is at right angles to the westward palaeo-ice flow, and palaeoglacial conditions on both rock types were similar. We report quantitative parameters for bedrock properties (Schmidt hammer hardness and joint spacing) and use morphometric parameters to analyse the landforms. Torridon sandstone is soft but thick-bedded and with a wide joint spacing. Erosional bedforms include roche moutonnées with smoothed tops and concave stoss sides, whalebacks, and elongate p-forms, indicating a high proportion of abrasion over plucking. Cambrian quartzite is hard but thin-bedded with narrow joint spacing. Erosional landforms are angular to subangular with abundant plucked lee faces, suggesting a high proportion of plucking over abrasion. Hardness and joint spacing thus exert a strong control on subglacial erosional landforms and the mechanisms that formed them. Thus glacial conditions (ice velocity, ice thickness) can only be inferred from glacial erosional landforms if the effects of bedrock properties of the substrate are considered.

  16. Development of pollutant release estimates due to abrasive blasting for lead paint removal from New York City Department of Transportation steel bridges

    SciTech Connect

    Lee, M.; Domanski, J.

    1999-07-01

    The use of abrasive blasting techniques in the removal of lead paint from steel bridges is a subject of public health and environmental concerns. This process creates airborne dust that must be appropriately contained to prevent inhalation or ingestion exposure during the removal activity, since some of that dust contains lead and other metals. Lead particles, if not appropriately contained, can also settle in local soils or on and within buildings, and can ultimately be inhaled or ingested. Potential worst case release scenarios for the release of dust and pollutants from paint removal operations were developed as part of the analysis framework for the Environmental Impact Statement for Lead Paint Removal Operations on New York City Department of Transportation Bridges. A multi-step analytical framework was developed for the Environmental Impact Statement (EIS), aimed at characterizing and quantifying a series of worst case scenarios for the release of contaminated material into the environment. The pollutants that the analysis focused on were lead, respirable particulates (PM10), Total Suspended Particulates (TSP) and other metals. Samples of existing paint obtained from various surfaces of representative bridges were analyzed to determine average paint dry film thickness and the concentration of metals in the paint for each of the representative bridges. Samples of expendable abrasives were analyzed to determine the concentration of metals within the abrasives. Six scenarios were developed to encompass the range of potential releases that can occur during blasting operations. Two subcategories of hypothetical release events were developed for each scenario-- reasonable worst case events and maximum worst case events. Air quality dispersion modeling with the Environmental Protection Agency's ISC3ST model was employed with the predicted release rates.

  17. Dynamic Bowtie Filter for Cone-Beam/Multi-Slice CT

    PubMed Central

    Liu, Fenglin; Yang, Qingsong; Cong, Wenxiang; Wang, Ge

    2014-01-01

    A pre-patient attenuator (“bowtie filter” or “bowtie”) is used to modulate an incoming x-ray beam as a function of the angle of the x-ray with respect to a patient to balance the photon flux on a detector array. While the current dynamic bowtie design is focused on fan-beam geometry, in this study we propose a methodology for dynamic bowtie design in multi-slice/cone-beam geometry. The proposed 3D dynamic bowtie is an extension of the 2D prior art. The 3D bowtie consists of a highly attenuating bowtie (HB) filled in with heavy liquid and a weakly attenuating bowtie (WB) immersed in the liquid of the HB. The HB targets a balanced flux distribution on a detector array when no object is in the field of view (FOV). The WB compensates for an object in the FOV, and hence is a scaled-down version of the object. The WB is rotated and translated in synchrony with the source rotation and patient translation so that the overall flux balance is maintained on the detector array. First, the mathematical models of different scanning modes are established for an elliptical water phantom. Then, a numerical simulation study is performed to compare the performance of the scanning modes in the cases of the water phantom and a patient cross-section without any bowtie and with a dynamic bowtie. The dynamic bowtie can equalize the numbers of detected photons in the case of the water phantom. In practical cases, the dynamic bowtie can effectively reduce the dynamic range of detected signals inside the FOV. Furthermore, the WB can be individualized using a 3D printing technique as the gold standard. We have extended the dynamic bowtie concept from 2D to 3D by using highly attenuating liquid and moving a scale-reduced negative copy of an object being scanned. Our methodology can be applied to reduce radiation dose and facilitate photon-counting detection. PMID:25051067

  18. WC-Co and Cr3C2-NiCr Coatings in Low- and High-Stress Abrasive Conditions

    NASA Astrophysics Data System (ADS)

    Kašparová, Michaela; Zahálka, František; Houdková, Šárka

    2011-03-01

    The article deals with the evaluation of abrasive wear resistance and adhesive strength of thermally sprayed coatings. The main attention was paid to differences between low- and high-stress abrasive conditions of the measuring. Conclusions include the evaluation of specific properties of the WC-Co and the Cr3C2-NiCr High Velocity Oxygen Fuel coatings and the evaluation of the changes in the behavior of the abrasive media. Mainly, the relationship between the low- and high-stress abrasion conditions and the wear mechanism in the tested materials was described. For the wear test, the abrasive media of Al2O3 and SiO2 sands were chosen. During wear tests, the volume loss of the tested materials and the surface roughness of the wear tracks were measured. The wear tracks on the tested materials and abrasive sands' morphologies were observed using Scanning Electron Microscopy. It was found that high-stress abrasive conditions change the coatings' behavior very significantly, particularly that of the Cr3C2-NiCr coating. Adhesive-cohesive properties of the coatings and relationships among individual structure particles were evaluated using tensile testing. It was found that the weak bond strength among the individual splats, structure particles, and phases plays a role in the poor wear resistance of the coatings.

  19. Effect of simultaneous infrared dry-blanching and dehydration on quality characteristics of carrot slices

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study investigated the effects of various processing parameters on carrot slices exposed to infrared (IR) radiation heating for achieving simultaneous infrared dry-blanching and dehydration (SIRDBD). The investigated parameters were product surface temperature, slice thickness and processing ti...

  20. Comparison between PEEK and Ti6Al4V concerning micro-scale abrasion wear on dental applications.

    PubMed

    Sampaio, M; Buciumeanu, M; Henriques, B; Silva, F S; Souza, J C M; Gomes, J R

    2016-07-01

    In the oral cavity, abrasive wear is predictable at exposed tooth or restorative surfaces, during mastication and tooth brushing. Also, wear can occur at contacting surfaces between the Ti-based prosthetic structures and implants in presence of abrasive compounds from food or toothpaste. Thus, the aim of this work was to compare the abrasive wear resistance of PEEK and Ti6Al4V on three-body abrasion related to different hydrated silica content and loads. Surfaces of Ti6Al4V or PEEK cylinders (8mm diameter and 4mm height) were wet ground on SiC papers and then polished with 1µm diamond paste. After that, surfaces were ultrasonically cleaned in propyl alcohol for 15min and then in distilled water for 10min. Micro-scale abrasion tests were performed at 60rpm and on different normal loads (0.4, 0.8 or 1.2N) after 600 ball revolutions using suspensions with different weight contents of hydrated silica. After abrasive tests, wear scars on flat samples were measured to quantify the wear volume and characterized by scanning electron microscope (SEM) to identify the dominant wear mechanisms. Results showed a higher volume loss rate on PEEK than that recorded on Ti6Al4V,, when subjected to three-body abrasion tests involving hydrated silica suspensions. An increase in volume loss was noted on both tested materials when the abrasive content or load was increased. PEEK was characterized by less wear resistance than that on Ti6Al4V after micro-scale abrasion wear in contact with hydrated silica particles, as commonly found in toothpastes. PMID:26849309