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Sample records for abrasion tool rat

  1. 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.

  2. 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.

  3. 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.

  4. Diamond-Fluoroplastic Composites for Abrasive Tools

    NASA Astrophysics Data System (ADS)

    Adrianova, O. A.; Kirillin, A. D.; Chersky, I. N.

    2001-07-01

    Composite materials based on polytetrafluoroethylene (PTFE) and natural technical diamond powders from Yakutia diamond deposits are developed. It is shown that the compositions based on PTFE and a technical diamond powder at a content of up to 60 wt.%, due to their good physicomechanical characteristics, low friction coefficient, and good wetting of diamond particles by polymer, make is possible to create abrasive tools for polishing and grinding hard metals and semiprecious and precious stones with high serviceability and operational life combined with a considerable increase in the quality of treated surfaces and operational stability of the tools. It is found that PTFE, being a more elastic and softer matrix than the traditional ones, exhibits a self-sharpening effect of diamond grains upon grinding hard surfaces, when the grains go deep into the elastic matrix, the matrix wears out, and the working part of the tool becomes enriched with the diamond powder. These conclusions are confirmed by electron microscopic investigations. It is shown that the introduction of ultradisperse fillings (up to 2 wt.%) into such compositions allows us to improve the characteristics of abrasive tools considerably, especially for grinding hard semiprecious stones. The physicomechanical and frictional characteristics of the compositions and specific examples of their application in the jewelry industry and in stone working are discussed.

  5. 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.

  6. Recent Results from the Mars Exploration Rover Rock Abrasion Tool

    NASA Astrophysics Data System (ADS)

    Cohen, J.; Paulsen, G.; Davis, K.; Gorevan, S.; Zacny, K.

    2009-12-01

    The Rock Abrasion Tool (RAT) serves as the sample preparation device on the Mars Exploration Rovers (MER) science payload. The RAT grinds Martian rock in a cylindrical volume, 45 mm in diameter and to a depth of up to 10 mm. This grinding action is intended to remove the altered outer layers of rock as well as overlying surface fines in preparation for imaging and spectral observations. In addition to acting as a facilitator for other instruments in the MER payload, RAT telemetry acquired during grinding may be used to assess the physical properties of the rocks that it grinds. RAT instruments on both Spirit and Opportunity have continued to operate and return useful data since 2004, despite minor problems that have recently occurred. The RAT on Spirit has recently been used for a purpose outside its original design capabilities: brushing away thin layers of loose soil without solid rock underneath. By progressing into the soil a few millimeters at a time, the RAT has been instrumental in helping to reveal the stratigraphy of this soft material. These results have helped in assessing soil properties and in turn will facilitate extrication of Spirit from its current location. Recent results from the Mars Exploration Rovers are presented along with data from laboratory RAT testing.

  7. 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.

  8. 29 CFR 1926.303 - Abrasive wheels and tools.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    .... (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 sides... Protection of Abrasive Wheels. All other portable abrasive wheels used for external grinding, shall...

  9. 29 CFR 1926.303 - Abrasive wheels and tools.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    .... (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 sides... Protection of Abrasive Wheels. All other portable abrasive wheels used for external grinding, shall...

  10. 29 CFR 1926.303 - Abrasive wheels and tools.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    .... (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 sides... Protection of Abrasive Wheels. All other portable abrasive wheels used for external grinding, shall...

  11. 29 CFR 1926.303 - Abrasive wheels and tools.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    .... (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 sides... Protection of Abrasive Wheels. All other portable abrasive wheels used for external grinding, shall...

  12. 29 CFR 1926.303 - Abrasive wheels and tools.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    .... (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 sides... Protection of Abrasive Wheels. All other portable abrasive wheels used for external grinding, shall...

  13. Design of abrasive tool for high-rate grinding

    NASA Astrophysics Data System (ADS)

    Ilinykh, AS

    2017-02-01

    The experimental studies aimed to design heavy-duty abrasive wheels for high-rate grinding are presented. The design of abrasive wheels with the working speed up to 100 m/s is based on the selection of optimized material composition and manufacture technology of the wheels.

  14. 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…

  15. 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

  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.; 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

  17. 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.

  18. Abrasive water suspension jet -- A multifunctional working tool for underwater applications

    SciTech Connect

    Brandt, C.; Louis, H.; Meier, G.; Tebbing, G.

    1995-12-31

    It is the aim of the paper to show the possibilities of Abrasive Water Suspension Jets (AWSJ) for underwater machining tasks in the offshore industry and other deep sea operations. The AWSJ is a remote-controllable and multifunctional tool for different underwater purposes like maintenance and repair as well as salvage, removal and decommissioning. Therefore it is possible to clean structures from rust and marine growth, to remove concrete and other functional coatings, to cut through different materials as well as composite materials and also to carry out the preparation for repair welding. First the paper will give some basic information about Abrasive Water Jets under water and about the equipment to produce AWSJ. Afterwards the possibilities of jet generation for cutting (round jet), cleaning and material removal (flat jet) and multifunctional operation will be demonstrated. Test results which were carried out under water will be presented. The influence of relevant parameters on processing efficiency is given and discussed.

  19. The Effectiveness of Power Tool Cleaning as an Alternative to Abrasive Blasting

    DTIC Science & Technology

    1995-06-01

    harshness. Therefore, both surface preparation and coating requirements may vary on each block. Power tools may provide adequate surface cleanliness for the...cleaning. 3. OBJECTIVES 1. Review the state-of-the-art of the power tool cleaning technology, evaluating the quality of surface cleanliness produced and...Assessing the Quality of Surface Cleanliness and Profile:’ Applicator Training Bulletin, July 1990, pp. 53-54. 17. Surface Conditioning Application Notes

  20. Online tools for understanding rat physiology

    PubMed Central

    2010-01-01

    Rat models have been used to investigate physiological and pathophysiological mechanisms for decades. With the availability of the rat genome and other online resources, tools to identify rat models that mimic human disease are an important step in translational research. Despite the large number of papers published each year using rat models, integrating this information remains a problem. Resources for the rat genome are continuing to grow rapidly, while resources providing access to rat phenotype data are just emerging. An overview of rat models of disease, tools to characterize strain by phenotype and genotype, and steps being taken to integrate rat physiological data is presented in this article. Integrating functional and physiological data with the rat genome will build a solid research platform to facilitate innovative studies to unravel the mechanisms resulting in disease. PMID:20056729

  1. Corneal Abrasions

    MedlinePlus

    ... Causes a Corneal Abrasion? Your eye has other defenses besides the orbital bone: The eyelids and eyelashes ... The Nemours Foundation, iStock, Getty Images, Corbis, Veer, Science Photo Library, Science Source Images, Shutterstock, and Clipart. ...

  2. Corneal Abrasions

    MedlinePlus

    ... fingernails short, too.Use care when putting in contact lenses. Make sure you clean them properly each day.Don’t sleep in your contact lenses.Trim low-hanging tree branches. Corneal abrasion treatment ...

  3. Corneal Abrasions

    MedlinePlus

    ... can damage the cornea. This includes dust, sand, wood shavings, hay, sparks, bugs, pieces of paper, and ... prevent a corneal abrasion, make sure to wear protection for your eyes, such as safety goggles or ...

  4. Postoperative anti-adhesion ability of a novel carboxymethyl chitosan from silkworm pupa in a rat cecal abrasion model.

    PubMed

    Zhu, Lin; Zhang, Yu-Qing

    2016-04-01

    N,O-Carboxymethyl chitosan (NOCC) can prevent postsurgical adhesion formation. Here, we described the preparation of a novel silkworm pupa NOCC and its effects on the prevention of postoperative adhesion in a rat cecal abrasion model. The degree of deacetylation (DDA) of silkworm pupa chitosan was only 49.87 ± 0.86%; regardless, it was used as the raw material to construct the novel silkworm pupa NOCC, which had a weaker crystallinity than the NOCC standard. Sixty male Sprague-Dawley rats were divided into three groups and treated as follows: 0.9% normal saline solution as a negative control, medical anti-adhesion gel as a positive control and the silkworm pupa NOCC anti-adhesion solution. Two and three weeks after surgery, the animals were killed and the adhesion formation was scored. The silkworm pupa NOCC solution significantly decreased the levels of WBC, TNF-α, IL-1β, IL-2, IL-6 and IL-8 but had no effect on IL-4. Additionally, a lower level of TGF-β1 expression was found in the silkworm pupa NOCC group, and significantly less collagen (P<0.01) and fewer inflammatory cells and fibroblasts were detected in the animals of this group. These results suggested that the novel NOCC from silkworm pupa using the method described here have potential applications in the prevention of postoperative intestinal adhesion.

  5. Tool-use by rats (Rattus norvegicus): tool-choice based on tool features.

    PubMed

    Nagano, Akane; Aoyama, Kenjiro

    2017-03-01

    In the present study, we investigated whether rats (Rattus norvegicus) could be trained to use tools in an experimental setting. In Experiment 1, we investigated whether rats became able to choose appropriate hook-shaped tools to obtain food based on the spatial arrangements of the tool and food, similar to tests conducted in non-human primates and birds. With training, the rats were able to choose the appropriate hooks. In Experiments 2 and 3, we conducted transfer tests with novel tools. The rats had to choose between a functional and non-functional rake-shaped tool in these experiments. In Experiment 2, the tools differed from those of Experiment 1 in terms of shape, color, and texture. In Experiment 3, there was a contradiction between the appearance and the functionality of these tools. The rats could obtain the food with a functional rake with a transparent blade but could not obtain food with a non-functional rake with an opaque soft blade. All rats chose the functional over the non-functional rakes in Experiment 2, but none of the rats chose the functional rake in Experiment 3. Thus, the rats were able to choose the functional rakes only when there was no contradiction between the appearance and functionality of the tools. These results suggest that rats understand the spatial and physical relationships between the tool, food, and self when there was no such contradiction.

  6. CAD/CAM-based Position/Force Control for a Ball-End Abrasive Tool and Its Application to an Industrial Robot

    NASA Astrophysics Data System (ADS)

    Nagata, Fusaomi; Hase, Tetsuo; Haga, Zenku; Omoto, Masaaki; Watanabe, Keigo

    Control of robotic mold polishing is considered in this paper. CAD/CAM-based position/force controller that simultaneously performs stable force control and exact pick feed control along curved surface is presented for articulated-type industrial robots. The force feedback loop controls the polishing force consisting of the contact force and the kinetic friction force. During mold polishing, the position feedback loop has a delicate contribution to the force feedback loop in Cartesian space so that the abrasive tool does not deviate from the desired trajectory but keeps a constant pick feed. When a mold polishing robot runs, cutter location (CL) data with normal vectors are used for not only a desired trajectory of tool translational motion but also desired contact directions given to a mold. The CL data allow the robot to realize a complete non-taught operation of the position and the contact direction. In this paper, a simple experiment is conducted by using an industrial robot with a ball-end abrasive tool in order to evaluate the effectiveness of the proposed method. The target workpiece is an aluminum PET bottle blow mold after NC machining, whose curved surface has small cusp marks with each pick feed of about 0.3 mm height. The results show that the proposed mold polishing robot with the CAD/CAM-based position/force controller can uniformly remove the cusp marks and further achieve mirror-like surface quality without undesirable over-polishing.

  7. 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.

  8. Treating corneal abrasions.

    PubMed

    Wingate, S

    1999-06-01

    Although corneal abrasions are commonly seen in primary care settings, the primary care literature contains scant references on detecting and managing this problem. This article provides an overview of corneal abrasion assessment and treatment. Four common etiologies of abrasion are discussed: traumatic abrasion, contact lens abrasion, foreign body abrasion, and recurrent erosion. Parameters for the history and physical examination are outlined, including sections on contact lens removal, lid eversion, and fluorescein staining. Treatment regimens for each of the etiologies are discussed, with a focus on current research on using pressure eye patches as an intervention. Indications for referral to an ophthalmologist are noted.

  9. Mobile load simulators - A tool to distinguish between the emissions due to abrasion and resuspension of PM10 from road surfaces

    NASA Astrophysics Data System (ADS)

    Gehrig, R.; Zeyer, K.; Bukowiecki, N.; Lienemann, P.; Poulikakos, L. D.; Furger, M.; Buchmann, B.

    2010-12-01

    Mechanically produced abrasion particles and resuspension processes are responsible for a significant part of the PM10 emissions of road traffic. However, specific differentiation between PM10 emissions due to abrasion and resuspension from road pavement is very difficult due to their similar elemental composition and highly correlated variation in time. In this work Mobile Load Simulators were used to estimate PM10 emission factors for pavement abrasion and resuspension on different pavement types for light and heavy duty vehicles. From the experiments it was derived that particle emissions due to abrasion from pavements in good condition are quite low in the range of only a few mg·km -1 per vehicle if quantifiable at all. Considerable abrasion emissions, however, can occur from damaged pavements. Resuspension of deposited dust can cause high and extremely variable particle emissions depending strongly on the dirt load of the road surface. Porous pavements seem to retain deposited dust better than dense pavements, thus leading to lower emissions due to resuspension compared to pavements with a dense structure (e.g. asphalt concrete). Tyre wear seemed not to be a quantitatively significant source of PM10 emissions from road traffic.

  10. PyRAT - python radiography analysis tool (u)

    SciTech Connect

    Temple, Brian A; Buescher, Kevin L; Armstrong, Jerawan C

    2011-01-14

    PyRAT is a radiography analysis tool used to reconstruction images of unknown 1-0 objects. The tool is written in Python and developed for use on LINUX and Windows platforms. The tool is capable of performing nonlinear inversions of the images with minimal manual interaction in the optimization process. The tool utilizes the NOMAD mixed variable optimization tool to perform the optimization.

  11. 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...

  12. 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.

  13. 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.

  14. Contact air abrasion.

    PubMed

    Porth, R

    1999-05-01

    The advantages of contact air abrasion techniques are readily apparent. The first, of course, is the greatly increased ease of use. Working with contact also tends to speed the learning curve by giving the process a more natural dental feel. In addition, as one becomes familiar with working with a dust stream, the potential for misdirecting the air flow is decreased. The future use of air abrasion for deep decay removal will make this the treatment of choice for the next millennium.

  15. Rat on Mars

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image taken on Mars by the panoramic camera on the Mars Exploration Rover Opportunity shows the rover's rock abrasion tool, also known as 'rat' (circular device in center), located on its instrument deployment device, or 'arm.' The image was acquired on the ninth martian day or sol of the rover's mission.

  16. 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.

  17. 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

  18. Wind abrasion on Mars

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1991-01-01

    Aeolian activity was predicted for Mars from earth based observations of changing surface patterns that were interpreted as dust storms. Mariner 9 images showed conclusive evidence for aeolian processes in the form of active dust storms and various aeolian landforms including dunes and yardangs. Windspeeds to initiate particle movement are an order of magnitude higher on Mars than on Earth because of the low atmospheric density on Mars. In order to determine rates of abrasion by wind blown particles, knowledge of three factors is required: (1) particle parameters such as numbers and velocities of windblown grains as functions of windspeeds at various heights above the surface; (2) the susceptibility to abrasion of various rocks and minerals; and (3) wind frequencies and speeds. For estimates appropriate to Mars, data for the first two parameters can be determined through lab and wind tunnel tests; data for the last two factors are available directly from the Viking Lander meteorology experiments for the two landing sites.

  19. 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.

  20. 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.

  1. Reliability automation tool (RAT) for fault tolerance computation

    NASA Astrophysics Data System (ADS)

    Singh, N. S. S.; Hamid, N. H.; Asirvadam, V. S.

    2012-09-01

    As CMOS transistors reduced in size, the circuit built using these nano-scale transistors naturally becomes less reliable. The reliability reduction, which is the measure of circuit performance, has brought up so many challenges in designing modern logic integrated circuit. Therefore, reliability modeling is increasingly important subject to be considered in designing modern logic integrated circuit. This drives a need to compute reliability measures for nano-scale circuits. This paper looks into the development of reliability automation tool (RAT) for circuit's reliability computation. The tool is developed using Matlab programming language based on the reliability evaluation model called Probabilistic Transfer Matrix (PTM). RAT allows users to significantly speed-up the reliability assessments of nano-scale circuits. Users have to provide circuit's netlist as the input to RAT for its reliability computation. The netlist signifies the circuit's description in terms of Gate Profile Matrix (GPM), Adjacency Computation Matrix (ACM) and Grid Layout Matrix (GLM). GPM, ACM and GLM indicate the types of logic gates, the interconnection between these logic gates and the layout matrix of these logic gates respectively in a given circuit design. Here, the reliability assessment by RAT is carried out on Full Adder circuit as the benchmark test circuit.

  2. Robotic abrasive water jet cutting of aerostructure components

    SciTech Connect

    Davis, D.C.

    1989-01-01

    To reduce tooling and labor costs associated with net trimming of aerostructure components, a system has been designed and implemented which combines the flexibility and accuracy of robotics with the productivity of abrasive water jet cutting. The system is comprised of a large, six-axis gantry robot which uses specially developed abrasive water jet end effectors to trim the edge-of-panel (EOP) and integral stiffener blades. These end effectors employ compact catchers to contain the spent stream, and thereby eliminate the need for large catcher tanks commonly used in abrasive water jet cutting. The robot is offline programmed to perform trimming on large, complex contoured panels.

  3. An Early Diagnostic Tool for Diabetic Peripheral Neuropathy in Rats

    PubMed Central

    Kambiz, Shoista; van Neck, Johan W.; Cosgun, Saniye G.; van Velzen, Marit H. N.; Janssen, Joop A. M. J. L.; Avazverdi, Naim; Hovius, Steven E. R.; Walbeehm, Erik T.

    2015-01-01

    The skin’s rewarming rate of diabetic patients is used as a diagnostic tool for early diagnosis of diabetic neuropathy. At present, the relationship between microvascular changes in the skin and diabetic neuropathy is unclear in streptozotocin (STZ) diabetic rats. The aim of this study was to investigate whether the skin rewarming rate in diabetic rats is related to microvascular changes and whether this is accompanied by changes observed in classical diagnostic methods for diabetic peripheral neuropathy. Computer-assisted infrared thermography was used to assess the rewarming rate after cold exposure on the plantar skin of STZ diabetic rats’ hind paws. Peripheral neuropathy was determined by the density of intra-epidermal nerve fibers (IENFs), mechanical sensitivity, and electrophysiological recordings. Data were obtained in diabetic rats at four, six, and eight weeks after the induction of diabetes and in controls. Four weeks after the induction of diabetes, a delayed rewarming rate, decreased skin blood flow and decreased density of IENFs were observed. However, the mechanical hyposensitivity and decreased motor nerve conduction velocity (MNCV) developed 6 and 8 weeks after the induction of diabetes. Our study shows that the skin rewarming rate is related to microvascular changes in diabetic rats. Moreover, the skin rewarming rate is a non-invasive method that provides more information for an earlier diagnosis of peripheral neuropathy than the classical monofilament test and MNCV in STZ induced diabetic rats. PMID:25984949

  4. 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.

  5. 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.

  6. PyRAT (python radiography analysis tool): overview

    SciTech Connect

    Armstrong, Jerawan C; Temple, Brian A; Buescher, Kevin L

    2011-01-14

    PyRAT was developed as a quantitative tool for robustly characterizing objects from radiographs to solve problems such as the hybrid nonlinear inverse problem. The optimization software library that was used is the nonsmooth optimization by MADS algorithm (NOMAD). Some of PyRAT's features are: (1) hybrid nonlinear inverse problem with calculated x-ray spectrum and detector response; (2) optimization based inversion approach with goal of identifying unknown object configurations - MVO problem; (3) using functionalities of Python libraries for radiographic image processing and analysis; (4) using the Tikhonov regularization method of linear inverse problem to recover partial information of object configurations; (5) using a priori knowledge of problem solutions to define feasible region and discrete neighbor for the MVO problem - initial data analysis + material library {yields} a priori knowledge; and (6) using the NOMAD (C++ version) software in the object.

  7. Cyanoacrylates and corneal abrasion.

    PubMed

    Dean, B S; Krenzelok, E P

    1989-01-01

    Cyanoacrylate-containing adhesives such as Super Glue, Krazy Glue, and a vast array of artificial nail adhesives are monomers which rapidly polymerize and bond in the presence of water or weak bases. Inadvertent contact with skin or tissue can also cause rapid bonding with resultant irritation. To assess the magnitude of problems associated with ocular contamination involving cyanoacrylates, a 12-month prospective study was conducted. 34 cases (21 adult and 13 pediatric) were collected. In all cases, contaminated eyes were thoroughly irrigated with tepid water for 15 minutes. 15 patients (44%) suffered a corneal abrasion, as determined by ophthalmic exam, necessitating treatment with antibiotics, cycloplegics, and patching. Individuals reporting complete resolution were irrigated with 20 minutes of exposure, while patients suffering mechanical injury delayed decontamination for a minimum of 15 minutes. In addition to immediate irrigation of eyes exposed to cyanoacrylates, we recommend an ophthalmologic evaluation to rule out the possibility of mechanical injury.

  8. Can You Find the Rat Holes?

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Using its rock abrasion tool, otherwise known as 'Rat,' NASA's Mars Exploration Rover Opportunity dotted the slope of 'Endurance Crater' with dimples that give scientists a glimpse into its layered geologic history. This image from the rover's navigation camera, taken on sol 169 (July 15, 2004), highlights the prolific work of the robotic 'rodent.' How many Rat holes can you identify? You will be able to check your answer against an image to be posted soon with all the holes identified.

  9. 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.

  10. Abrasive water-jet cutting; remote hot cell application

    SciTech Connect

    Leist, K.J.; Funnell, G.J.

    1988-09-01

    In the process of selecting a failed equipment cut-up tool for the Process Facility Modifications (PFM) Project, a system using an Abrasive Water Jet (AWJ) was developed and tested for remote disassembly of failed equipment by the Westinghouse Hanford Company, PFM Mechanical Development Unit.

  11. Materials selection for abrasive duty

    SciTech Connect

    Not Available

    1987-04-01

    The abrasion of equipment caused by the throughput of large volumes of solids or dust is a major problem in mining, handling and processing minerals such as coal and limestone, and in the disposal of waste products such as ash. Loss of material from the surfaces over which these materials pass is caused by the combined effects of impact abrasion, sliding abrasion, and chemical attack. Factors which affect these processes include properties of the conveying medium, and properties of the solids, such as particle size, structural composition, size mix, as well as the velocity of the material, the bulk volume of material passing, and the frequency of plant operation. Guidelines are given for materials selection and the use of linings in the coal handling plant, pulverized coal pipework, and ash disposal plant is reviewed for coal-fired power plants.

  12. 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.

  13. New concepts in air abrasion.

    PubMed

    Porth, R N

    1998-03-01

    There is no doubt that air abrasion is going to be part of the millennial shift in dentistry away from traditional treatment modalities. With the change in incidence and morphology of caries as a result of the hardening effect of fluoride on enamel, this ability to remove only decayed areas and permanently seal the less susceptible areas becomes increasingly desirable.

  14. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) 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 shall... Protection of Abrasive Wheels, B7.1-1964. All other portable abrasive wheels used for external grinding...

  15. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) 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 shall... Protection of Abrasive Wheels, B7.1-1964. All other portable abrasive wheels used for external grinding...

  16. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) 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 shall... Protection of Abrasive Wheels, B7.1-1964. All other portable abrasive wheels used for external grinding...

  17. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) 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 shall... Protection of Abrasive Wheels, B7.1-1964. All other portable abrasive wheels used for external grinding...

  18. Grain decoration in aluminum oxynitride (ALON) from polishing on bound abrasive laps

    NASA Astrophysics Data System (ADS)

    Gregg, Leslie L.; Marino, Anne E.; Hayes, Jennifer C.; Jacobs, Stephen D.

    2004-01-01

    Aluminum oxynitride (ALON) is a polycrystalline material that has proven difficult to polish due to its grain structure. Bound abrasives are an effective means for polishing ALON, and work is being done with them to obtain good surfaces, with reasonable removal rates. Laps consisting of abrasives bound in epoxy matrices were created for polishing ALON. The effects of varying abrasive type, abrasive concentration, lap shape, coolant and load were studied. Metrology procedures were developed to monitor different aspects of the grain structure and numerically evaluate grain boundary decoration. Strategies were developed to polish ALON at acceptable rates with reasonably good surface quality. Work is directed toward finding optimal bound abrasive lap formulations that can be fabricated into ring and/or contour tools for testing on CNC machining platforms.

  19. Grain decoration in aluminum oxynitride (ALON) from polishing on bound abrasive laps

    NASA Astrophysics Data System (ADS)

    Marino, Anne E.; Hayes, Jennifer; Gregg, Leslie L.; Jacobs, Stephen D.

    2003-05-01

    Aluminum oxynitride (ALON) is a material with desirable qualities for a variety of applications that has proven difficult to polish because of its grain structure. Bound abrasives may prove to be an effective means of polishing it, and work is being done with them to obtain good surfaces on ALON, with reasonable removal rates. Laps consisting of abrasives bound in epoxy matrices have been created for polishing ALON. The effects of varying abrasive type, abrasive concentration, lap shape, coolant and load are being studied. Metrology procedures are being developed to monitor different aspects of the grain structure and numerically evaluate its decoration. Strategies have been developed to polish ALON at acceptable rates with reasonably good surface quality. Work is directed toward finding optimal bound abrasive lap formulations that can be fabricated into ring and/or contour tools for testing on CNC machining platforms.

  20. 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.

  1. 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.

  2. Measuring pebble abrasion on a mixed sand and gravel beach using abrasion baskets

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Stephenson, Wayne

    2015-11-01

    The abrasion of sediments on mixed sand and gravel beaches has important consequences for local sediment budgets as abrasion often accounts for the major loss of beach volume. Here we report an innovative method using abrasion baskets to measure abrasion in the swash zone of mixed sand and gravel beaches. This method offers significant advantages over laboratory-based tumbler experiments traditionally used to determine abrasion rates. The very high recovery rate from our method is also a significant advantage over previous field methods using radio frequency identification technology to measure abrasion where tagged particles are often lost. Either three or five abrasion baskets were placed across the swash zone on a mixed sand and gravel beach at Timaru, South Island, New Zealand, to measure the abrasion occurring on labeled sediments placed in the baskets. Over two experiments, results showed measurable abrasion across the swash zone with higher abrasion rates occurring in the middle of the swash zone and lower rates towards the swash limit and at the breaker zone. Results also illustrate the role of changing wave energy on abrasion loss. A relationship between particle size and abrasion rate was also found, similar to previous laboratory results reported in the literature. Our preliminary experiments lead us to define an abrasion zone and this idea may help shape future research on abrasion processes on mixed sand and gravel beaches.

  3. Experimental abrasion of detrital gold

    USGS Publications Warehouse

    Yeend, Warren E.

    1975-01-01

    The physical breakdown and abrasion rates of gold were studied using a tumbler to simulate natural high-energy environments. The gold fragments were tumbled for periods ranging from 30 to 240 h with different combinations of sand, cobbles, and water at velocities of 0.5 and 2.0 mi/h (0.85 and 3.22 km/h). With sand and gravel, the common bedload of the rivers that deposited the gold-bearing Tertiary sedimentary rocks of the Sierra Nevada, gold is abraded at rates of 0.015 to 0.007 percent (by weight) per hour of travel (at 0.5 mi/h or 0.845 km/h). Cobbles, rather than sand, are responsible for most of the physical changes and abrasion of the gold. Ten gold fragments tumbled for 120 h with cobbles and water (no sand) were broken down to 68 recoverable fragments and lost about 25 percent of their weight to particles smaller than could be recovered using conventional panning techniques. Gold tumbled for 120 h with sand and water lost less than 1 percent of its weight. Gold was abraded faster by wet sand than by dry sand. Velocity appears to be more important as a factor in abrasion of gold than travel distance a fourfold increase in velocity produced a tenfold increase in hourly abrasion rates of gold. Scanning electron microscope examination of the gold fragments after the tumbling experiments revealed differences in surface texture between fragments tumbled with (1) sand, (2) sand and cobbles, and (3) cobbles only.

  4. Air flow exploration of abrasive feed tube

    NASA Astrophysics Data System (ADS)

    Zhang, Shijin; Li, Xiaohong; Gu, Yilei

    2009-12-01

    An abrasive water-jet cutting process is one in which water pressure is raised to a very high pressure and forced through a very small orifice to form a very thin high speed jet beam. This thin jet beam is then directed through a chamber and then fed into a secondary nozzle, or mixing tube. During this process, a vacuum is generated in the chamber, and garnet abrasives and air are pulled into the chamber, through an abrasive feed tube, and mixes with this high speed stream of water. Because of the restrictions introduced by the abrasive feed tube geometry, a vacuum gradient is generated along the tube. Although this phenomenon has been recognized and utilized as a way to monitor nozzle condition and abrasive flowing conditions, yet, until now, conditions inside the abrasive feed line have not been completely understood. A possible reason is that conditions inside the abrasive feed line are complicated. Not only compressible flow but also multi-phase, multi-component flow has been involved in inside of abrasive feed tube. This paper explored various aspects of the vacuum creation process in both the mixing chamber and the abrasive feed tube. Based on an experimental exploration, an analytical framework is presented to allow theoretical calculations of vacuum conditions in the abrasive feed tube.

  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. Stable isotope analysis as an early monitoring tool for community-scale effects of rat eradication

    USGS Publications Warehouse

    Nigro, Katherine M.; Hathaway, Stacie A.; Wegmann, Alex; Miller-ter Kuile, Ana; Fisher, Robert N.; Young, Hillary S.

    2017-01-01

    Invasive rats have colonized most of the islands of the world, resulting in strong negative impacts on native biodiversity and on ecosystem functions. As prolific omnivores, invasive rats can cause local extirpation of a wide range of native species, with cascading consequences that can reshape communities and ecosystems. Eradication of rats on islands is now becoming a widespread approach to restore ecosystems, and many native island species show strong numerical responses to rat eradication. However, the effect of rat eradication on other consumers can extend beyond direct numerical effects, to changes in behavior, dietary composition, and other ecological parameters. These behavioral and trophic effects may have strong cascading impacts on the ecology of restored ecosystems, but they have rarely been examined. In this study, we explore how rat eradication has affected the trophic ecology of native land crab communities. Using stable isotope analysis of rats and crabs, we demonstrate that the diet or trophic position of most crabs changed subsequent to rat eradication. Combined with the numerical recovery of two carnivorous land crab species (Geograpsus spp.), this led to a dramatic widening of the crab trophic niche following rat eradication. Given the established importance of land crabs in structuring island communities, particularly plants, this suggests an unappreciated mechanism by which rat eradication may alter island ecology. This study also demonstrates the potential for stable isotope analysis as a complementary monitoring tool to traditional techniques, with the potential to provide more nuanced assessments of the community- and ecosystem-wide effects of restoration.

  8. Drawing Light-fields: Hand-drawn Approaches to Abrasion Holography

    NASA Astrophysics Data System (ADS)

    Duke, T.

    2013-02-01

    Abrasion holography has received little attention since the technique was described by William J. Beaty in the early 1990's. In this paper the limitations of abrasion holography are explored, and new approaches are presented which expand the possibilities of the medium. New tools presented here offer new possibilities to the artist wishing to draw holograms by hand. Methods are described by which complex curves and organic forms can be constructed by hand more easily and intuitively than previously described. In an analysis of reconstruction lighting and viewing geometries, new solutions to reduce or eliminate distortions are suggested. Various tools, materials, and scratch geometries are considered for optimum 3D illusion. A new class of abrasion holograms is presented that use elliptical, hypotrochoidal, and epitrochoidal scratch geometries, exhibiting novel animation effects. In conclusion, a method for embossing abrasion holograms with the aid of an etching press is described.

  9. Rate of wind abrasion on Mars

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Leach, R. N.; Williams, S. H.; Krinsley, D. H.; Marshall, J. R.; White, B. R.; Pollack, J. B.

    1982-01-01

    A brief description is given of the experiments performed to obtain data on windblown particles and abrasion of rocks in a simulated Martian environment. Preliminary results are presented and combined with Viking meteorological data in estimating rates of wind abrasion at the VL-1 site on Mars. Attention is also given to the implications that the results have for Martian surface history. Calculations of the present rates of abrasion by windblown particles on Mars yield values ranging from 0.021 cm/yr to nearly zero, depending on the target, the agent of abrasion, and the availability of windblown particles.

  10. A Study of the Pickup of Abrasive Particles during Abrasion of Annealed Aluminum on Silicon Carbide Abrasive Papers,

    DTIC Science & Technology

    annealed aluminium during abrasion on silicon carbide abrasive papers. Neither optical nor scanning electron microscopy adequately characterises the...despite its limitations when examining rough surfaces. The present results show that the pickup of silicon carbide particles increases with increase in

  11. Restorative resins: abrasion vs. mechanical properties.

    PubMed

    Jørgensen, K D

    1980-12-01

    The purpose of the present work was to examine whether it is possible by simple and reliable laboratory tests to evaluate the abrasion by food of Class 1 restorative resins. The results point to the following main conclusions: for the smooth-surface resins, i.e. the micro-filled composite and the unfilled resins, the Wallace hardness test appears to be a valid parameter for abrasion; the greater the depth of penetration of the Vickers diamond of this apparatus, the more severe abrasion is to be expected. The mode of abrasion in this type of resin is scratching. Porosity in the resins strongly enhances the abrasion. For the rough-surface resins, i.e. the conventional composites, a dual effect of the filler particles was concluded. The filler particles on the one hand protect the matrix against abrasion, but cause, on the other hand, in time an increase of the surface roughness of the composite and thereby via increased friction an increase of the abrasion. Considerations on possible ways to improve the present-day restorative resins are presented. It is stressed that the results obtained refer only to abrasion of Class 1 fillings by food.

  12. 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.

  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.

  14. Computational tool for morphological analysis of cultured neonatal rat cardiomyocytes.

    PubMed

    Leite, Maria Ruth C R; Cestari, Idágene A; Cestari, Ismar N

    2015-08-01

    This study describes the development and evaluation of a semiautomatic myocyte edge-detector using digital image processing. The algorithm was developed in Matlab 6.0 using the SDC Morphology Toolbox. Its conceptual basis is the mathematical morphology theory together with the watershed and Euclidean distance transformations. The algorithm enables the user to select cells within an image for automatic detection of their borders and calculation of their surface areas; these areas are determined by adding the pixels within each myocyte's boundaries. The algorithm was applied to images of cultured ventricular myocytes from neonatal rats. The edge-detector allowed the identification and quantification of morphometric alterations in cultured isolated myocytes induced by 72 hours of exposure to a hypertrophic agent (50 μM phenylephrine). There was a significant increase in the mean surface area of the phenylephrine-treated cells compared with the control cells (p<;0.05), corresponding to cellular hypertrophy of approximately 50%. In conclusion, this edge-detector provides a rapid, repeatable and accurate measurement of cell surface areas in a standardized manner. Other possible applications include morphologic measurement of other types of cultured cells and analysis of time-related morphometric changes in adult cardiac myocytes.

  15. Checking Out Cuts, Scratches, and Abrasions

    MedlinePlus

    ... to get rid of the infection. Luckily, most cuts, scratches, and abrasions will go away on their own, thanks to your body's amazing ability to heal ... Story on Scars Cellulitis Taking Care of Your Skin What's a Scab? ...

  16. Abrasion and resistant discharge valve developed

    NASA Technical Reports Server (NTRS)

    Gottwald, W. L.

    1969-01-01

    Discharge valve capable of withstanding intense radiation and high abrasion was developed for use in a fluidized bed reactor. The valve which employs a replaceable Teflon seal, has only one moving part and is designed for remote assembly and disassembly.

  17. Abrasion Collar Around Shrapnel Entry Wound.

    PubMed

    Gujaral, Pootheril Balan; Ajay, Balachandran

    2017-02-28

    Abrasion collar is usually described as a feature of bullet entry wounds caused by friction and indentation. The present case is that of the peculiar entry wound caused by a piece of flying shrapnel which was ejected from a furnace in a steel plant. The scrap metal which exploded in the plant was sourced from the West Asia region. The entry wound on the chest was circular and had an abrasion collar around it. The projectile was a cylindrical object of obscure origin. The forensic science laboratory put forth the possibility that the projectile was a component of an artillery fuze. A decades old study which employed high-speed photography has rejected the possibility that abrasion collars are produced by friction. High-velocity projectiles other than bullets can also produce abrasion collars as the rubbing of the bullet against the skin or its rotation are not the causative mechanisms.

  18. 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.

  19. 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.

  20. Investigations on the trajectories of magnetic abrasive grains in magnetic induction-free abrasive wire sawing

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Yao, Chunyan; Tang, Chen; Qiu, Tengwei; Xu, Xuefeng

    2016-12-01

    This study presents a novel method of magnetic induction-free abrasive wire sawing. The ferromagnetic wire is magnetized in a uniform magnetic field, forming a high-gradient magnetic field that separates into paramagnetic and diamagnetic regions. Paramagnetic abrasive grains are attracted to the paramagnetic region and adhere to the wire surface but are repelled from the diamagnetic region. The trajectory of the magnetic abrasive grains is analyzed in a mathematical model and in COMSOL Multiphysics simulations. The results are verified by test investigations on the motions and adsorption of the magnetic abrasive grains using a dynamic microscope system. The detailed grain trajectories are investigated in a numerical model. Because it actively transports grains toward the wire (where they can be transported to the sawing channel), our proposed method achieves more efficient wire sawing performance than traditional free abrasive wire sawing. Such efficient performance is highly sought in silicon wafering technologies, which are commonly used in the solar and semiconductor industries.

  1. 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.

  2. 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...

  3. Recombinase-driver rat lines: tools, techniques, and optogenetic application to dopamine-mediated reinforcement.

    PubMed

    Witten, Ilana B; Steinberg, Elizabeth E; Lee, Soo Yeun; Davidson, Thomas J; Zalocusky, Kelly A; Brodsky, Matthew; Yizhar, Ofer; Cho, Saemi L; Gong, Shiaoching; Ramakrishnan, Charu; Stuber, Garret D; Tye, Kay M; Janak, Patricia H; Deisseroth, Karl

    2011-12-08

    Currently there is no general approach for achieving specific optogenetic control of genetically defined cell types in rats, which provide a powerful experimental system for numerous established neurophysiological and behavioral paradigms. To overcome this challenge we have generated genetically restricted recombinase-driver rat lines suitable for driving gene expression in specific cell types, expressing Cre recombinase under the control of large genomic regulatory regions (200-300 kb). Multiple tyrosine hydroxylase (Th)::Cre and choline acetyltransferase (Chat)::Cre lines were produced that exhibited specific opsin expression in targeted cell types. We additionally developed methods for utilizing optogenetic tools in freely moving rats and leveraged these technologies to clarify the causal relationship between dopamine (DA) neuron firing and positive reinforcement, observing that optical stimulation of DA neurons in the ventral tegmental area (VTA) of Th::Cre rats is sufficient to support vigorous intracranial self-stimulation (ICSS). These studies complement existing targeting approaches by extending the generalizability of optogenetics to traditionally non-genetically-tractable but vital animal models.

  4. Hardfacing and wear plates battle abrasion

    SciTech Connect

    Miller, R.F.

    1983-06-01

    This article examines abrasion-resistant steels and hardfacing as two effective weapons at the disposal of material handlers. It points out that abrasion is probably the single most destructive form of wear in the mixing and processing of coal. Particulate matter such as quartz sand and other minerals including coal curtail in-service life of dragline buckets, chute, crusher rolls, gates and valves, exhauster fan blades, target plates, truck beds, hoppers, vibrating pans, grinding mills, piping elbows, etc. The advantages of abrasion-resistant steels and hardfacing can be obtained in the form of a composite wear plate-hardfacing on a carbon steel backup plate. It concludes that the composite wear plate represents a major innovation since its advantages include ease of handling, low cost and easy installation, minimum on-site welding time and versatility. Its use is limited only to the consumer's creativity in application.

  5. 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.

  6. Computational Fluid Dynamics Analysis of Nozzle in Abrasive Water Jet Machining

    NASA Astrophysics Data System (ADS)

    Venugopal, S.; Chandresekaran, M.; Muthuraman, V.; Sathish, S.

    2017-03-01

    Abrasive water jet cutting is one of the most recently developed non-traditional manufacturing technologies. The general nature of flow through the machining, results in rapid wear of the nozzle which decrease the cutting performance. It is well known that the inlet pressure of the abrasive water suspension has main effect on the erosion characteristics of the inner surface of the nozzle. The objective of the project is to analyze the effect of inlet pressure on wall shear and exit kinetic energy. The analysis would be carried out by varying the inlet pressure of the nozzle, so as to obtain optimized process parameters for minimum nozzle wear. The two phase flow analysis would be carried by using computational fluid dynamics tool CFX. The availability of minimized process parameters such as of abrasive water jet machining (AWJM) is limited to water and experimental test can be cost prohibitive.

  7. 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

  8. Computational Fluid Dynamic Simulation of Flow in Abrasive Water Jet Machining

    NASA Astrophysics Data System (ADS)

    Venugopal, S.; Sathish, S.; Jothi Prakash, V. M.; Gopalakrishnan, T.

    2017-03-01

    Abrasive water jet cutting is one of the most recently developed non-traditional manufacturing technologies. In this machining, the abrasives are mixed with suspended liquid to form semi liquid mixture. The general nature of flow through the machining, results in fleeting wear of the nozzle which decrease the cutting performance. The inlet pressure of the abrasive water suspension has main effect on the major destruction characteristics of the inner surface of the nozzle. The aim of the project is to analyze the effect of inlet pressure on wall shear and exit kinetic energy. The analysis could be carried out by changing the taper angle of the nozzle, so as to obtain optimized process parameters for minimum nozzle wear. The two phase flow analysis would be carried by using computational fluid dynamics tool CFX. It is also used to analyze the flow characteristics of abrasive water jet machining on the inner surface of the nozzle. The availability of optimized process parameters of abrasive water jet machining (AWJM) is limited to water and experimental test can be cost prohibitive. In this case, Computational fluid dynamics analysis would provide better results.

  9. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing... that contains an abrasive material, such as silica pumice, intended to remove debris from the...

  10. 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....

  11. 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...

  12. 9 CFR 311.14 - Abrasions, bruises, abscesses, pus, etc.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Abrasions, bruises, abscesses, pus... PARTS § 311.14 Abrasions, bruises, abscesses, pus, etc. All slight, well-limited abrasions on the tongue... a carcass which is badly bruised or which is affected by an abscess, or a suppurating sore shall...

  13. Abrasive waterjet machining of fiber reinforced composites: A review

    NASA Astrophysics Data System (ADS)

    Kalla, D. K.; Dhanasekaran, P. S.; Zhang, B.; Asmatulu, R.

    2012-04-01

    Machining of fiber reinforced polymer (FRP) composites is a major secondary manufacturing activity in the aircraft and automotive industries. Traditional machining of these composites is difficult due to the high abrasiveness nature of their reinforcing constituents. Almost all the traditional machining processes involve in the dissipation of heat into the workpiece which can be resulted in damage to workpiece and rapid wear of the cutting tool. This serious issue has been overcome by water jetting technologies. Abrasive waterjet machining (AWJM) is a nontraditional method and one of the best options for machining FRPs. This paper presents a review of the ongoing research and development in AWJM of FRPs, with a critical review of the physics of the machining process, surface characterization, modeling and the newer application to the basic research. Variable cutting parameters, limitations and safety aspects of AWJM and the noise related issues due to high flow rate of water jet will be addressed. Further challenges and scope of the future development in AWJM are also presented in detail.

  14. Precision replenishable grinding tool and manufacturing process

    DOEpatents

    Makowiecki, Daniel M.; Kerns, John A.; Blaedel, Kenneth L.; Colella, Nicholas J.; Davis, Pete J.; Juntz, Robert S.

    1998-01-01

    A reusable grinding tool consisting of a replaceable single layer of abrasive particles intimately bonded to a precisely configured tool substrate, and a process for manufacturing the grinding tool. The tool substrate may be ceramic or metal and the abrasive particles are preferably diamond, but may be cubic boron nitride. The manufacturing process involves: coating a configured tool substrate with layers of metals, such as titanium, copper and titanium, by physical vapor deposition (PVD); applying the abrasive particles to the coated surface by a slurry technique; and brazing the abrasive particles to the tool substrate by alloying the metal layers. The precision control of the composition and thickness of the metal layers enables the bonding of a single layer or several layers of micron size abrasive particles to the tool surface. By the incorporation of an easily dissolved metal layer in the composition such allows the removal and replacement of the abrasive particles, thereby providing a process for replenishing a precisely machined grinding tool with fine abrasive particles, thus greatly reducing costs as compared to replacing expensive grinding tools.

  15. Precision replenishable grinding tool and manufacturing process

    DOEpatents

    Makowiecki, D.M.; Kerns, J.A.; Blaedel, K.L.; Colella, N.J.; Davis, P.J.; Juntz, R.S.

    1998-06-09

    A reusable grinding tool consisting of a replaceable single layer of abrasive particles intimately bonded to a precisely configured tool substrate, and a process for manufacturing the grinding tool are disclosed. The tool substrate may be ceramic or metal and the abrasive particles are preferably diamond, but may be cubic boron nitride. The manufacturing process involves: coating a configured tool substrate with layers of metals, such as titanium, copper and titanium, by physical vapor deposition (PVD); applying the abrasive particles to the coated surface by a slurry technique; and brazing the abrasive particles to the tool substrate by alloying the metal layers. The precision control of the composition and thickness of the metal layers enables the bonding of a single layer or several layers of micron size abrasive particles to the tool surface. By the incorporation of an easily dissolved metal layer in the composition such allows the removal and replacement of the abrasive particles, thereby providing a process for replenishing a precisely machined grinding tool with fine abrasive particles, thus greatly reducing costs as compared to replacing expensive grinding tools. 11 figs.

  16. OntoMate: a text-mining tool aiding curation at the Rat Genome Database

    PubMed Central

    Liu, Weisong; Laulederkind, Stanley J. F.; Hayman, G. Thomas; Wang, Shur-Jen; Nigam, Rajni; Smith, Jennifer R.; De Pons, Jeff; Dwinell, Melinda R.; Shimoyama, Mary

    2015-01-01

    The Rat Genome Database (RGD) is the premier repository of rat genomic, genetic and physiologic data. Converting data from free text in the scientific literature to a structured format is one of the main tasks of all model organism databases. RGD spends considerable effort manually curating gene, Quantitative Trait Locus (QTL) and strain information. The rapidly growing volume of biomedical literature and the active research in the biological natural language processing (bioNLP) community have given RGD the impetus to adopt text-mining tools to improve curation efficiency. Recently, RGD has initiated a project to use OntoMate, an ontology-driven, concept-based literature search engine developed at RGD, as a replacement for the PubMed (http://www.ncbi.nlm.nih.gov/pubmed) search engine in the gene curation workflow. OntoMate tags abstracts with gene names, gene mutations, organism name and most of the 16 ontologies/vocabularies used at RGD. All terms/ entities tagged to an abstract are listed with the abstract in the search results. All listed terms are linked both to data entry boxes and a term browser in the curation tool. OntoMate also provides user-activated filters for species, date and other parameters relevant to the literature search. Using the system for literature search and import has streamlined the process compared to using PubMed. The system was built with a scalable and open architecture, including features specifically designed to accelerate the RGD gene curation process. With the use of bioNLP tools, RGD has added more automation to its curation workflow. Database URL: http://rgd.mcw.edu PMID:25619558

  17. OntoMate: a text-mining tool aiding curation at the Rat Genome Database.

    PubMed

    Liu, Weisong; Laulederkind, Stanley J F; Hayman, G Thomas; Wang, Shur-Jen; Nigam, Rajni; Smith, Jennifer R; De Pons, Jeff; Dwinell, Melinda R; Shimoyama, Mary

    2015-01-01

    The Rat Genome Database (RGD) is the premier repository of rat genomic, genetic and physiologic data. Converting data from free text in the scientific literature to a structured format is one of the main tasks of all model organism databases. RGD spends considerable effort manually curating gene, Quantitative Trait Locus (QTL) and strain information. The rapidly growing volume of biomedical literature and the active research in the biological natural language processing (bioNLP) community have given RGD the impetus to adopt text-mining tools to improve curation efficiency. Recently, RGD has initiated a project to use OntoMate, an ontology-driven, concept-based literature search engine developed at RGD, as a replacement for the PubMed (http://www.ncbi.nlm.nih.gov/pubmed) search engine in the gene curation workflow. OntoMate tags abstracts with gene names, gene mutations, organism name and most of the 16 ontologies/vocabularies used at RGD. All terms/ entities tagged to an abstract are listed with the abstract in the search results. All listed terms are linked both to data entry boxes and a term browser in the curation tool. OntoMate also provides user-activated filters for species, date and other parameters relevant to the literature search. Using the system for literature search and import has streamlined the process compared to using PubMed. The system was built with a scalable and open architecture, including features specifically designed to accelerate the RGD gene curation process. With the use of bioNLP tools, RGD has added more automation to its curation workflow. Database URL: http://rgd.mcw.edu.

  18. [Evaluation of potential risks of abrasive water jet osteotomy in-vivo].

    PubMed

    Kuhlmann, C; Pude, F; Bishup, C; Krömer, S; Kirsch, L; Andreae, A; Wacker, K; Schmolke, S

    2005-10-01

    Since the 80's the water jet scalpel is an established tool in some surgical fields. It is used in particular in visceral surgery for preparation of parenchymatous organs. By the addition of biocompatible abrasives, this technique is able to effectively machine hard biological tissues. Free defined cutting geometries can be realised in a non contact process. Therewith this method has crucial advantages compared to conventional osteotomy techniques and gives new impulses to the development in endoprosthetics and correction osteotomies of hollow bones. In the presented work the new developed abrasive water injection jet (AWIJ) was used the first time for in-vivo osteotomies. Aim of this study was the detection of potential thrombembolic effects and wash in effects of the cutting fluid. Hollow bones of the fore and hind leg of 20 house pigs were treated with the new cutting technique. Intraoperative documentation of relevant vital parameters was performed by a multi monitoring system. Thrombembolic effects during the osteotomy were detected by transthoracic Doppler ultrasonography and transesophagale echocardiography. The hollow bones were prepared in consideration of the vascularisation's protection especially in respect to the venous flow. Thrombembolic effects with temporary haemodynamic respectively respiratory consequences could be detected exclusively by using the so called "3-component jet", which consists of 90 vol % of air. The usage of an abrasive suspension enables the airfree dosing of dry soluable abrasives. Thrombembolic effects could not be monitored in this case. Intramedullary fluid in-wash effects as well as resulting electrolytic disorders could not be proven. For abrasive waterjet osteotomies with 3 component jet a relevant risk of thrombembolic effects could be shown. This knowledge has also to be considered for abdominal and neurosurgical applications in the future. Due to the usage of an abrasive suspension this risk can fully be avoided.

  19. 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.

  20. Abrasive wear of alumina fibre-reinforced aluminium

    NASA Astrophysics Data System (ADS)

    Axen, N.; Alahelisten, A.; Jacobson, S.

    1994-04-01

    The friction and abrasive wear behaviour of an Al-Si1MgMn aluminium alloy reinforced with 10, 15 and 30 vol.% of alumina fibers has been evaluated. The influence of fiber content, matrix hardness, applied load as well as the hardness and size of the abrasive grits was investigated. The tests were performed with a pin-on-drum two-body abrasion apparatus. The wear mechanisms were studied using scanning electron microscopy. It is shown that fiber reinforcement increases the wear resistance in milder abrasive situations, i.e. small and soft abrasives and low loads. However, in tougher abrasive situations, meaning coarse and hard abrasives and high loads, the wear resistance of the composites is equal to or, in some cases, even lower than that of the unreinforced material. It is also shown that the coefficient of friction decreases with increasing fiber content and matrix hardness of the composites.

  1. A scanning electron-microscopic study of in vitro abrasion of mammalian tooth enamel under compressive loads.

    PubMed

    Maas, M C

    1994-01-01

    Microscopic tooth-wear (microwear) patterns can be an important tool for assessing modes and rates of abrasive tooth wear, but their analysis and interpretation is complicated by the fact that microwear is influenced by many factors. Three of these factors were here tested under conditions of compressive loading: (1) species differences in enamel structure, (2) abrasive particle size and (3) magnitude of force. Teeth of four species (Homo sapiens, Lemur fulvus, Ovis aries and Crocodylus rhombifer) were abraded in vitro using three sizes of abrasive silicon-carbide grit (average diameters 73, 23 and 14 microns), at two loads (50 and 100 kg). Microwear features were assessed by scanning electron microscopy of lightly etched enamel surfaces and epoxy replicas. Microwear pits (length:width < 4:1) were the predominant feature type. Factorial analysis of variance of rank-transformed, feature-area measurements demonstrated that, under conditions of compressive loading, the size of abrasive particles was the primary determinant of microwear size. These results contrast with previous experimental tests of abrasion by predominantly shearing loads, where feature size was influenced by interaction among experimental factors, including the microscopic orientation of enamel crystallites. Although magnitude of compressive force was not a factor in microwear size variation, it may be a critical factor in explaining the presence or absence of microwear on tooth surfaces. The relatively small compressive bite force generated during typical chewing may not consistently produce abrasive pitting. These experiments demonstrate that, as the same abrasive regime can produce both large and small pits, the mechanism by which wear features are formed (i.e. compression or adhesion) cannot be determined from the size of features alone. Nevertheless, the dependence of pit size on abrasive particle size demonstrates that metrical variation in wear features can elucidate important attributes of

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Critical evaluation of cysteamine as a tool to deplete somatostatin in the rat central nervous system

    SciTech Connect

    Cook, L.L.; Bissette, G.; Dole, K.; Nemeroff, C.B.

    1989-02-01

    The wide central nervous system (CNS) distribution of somatostatin (SRIF) as well as the well documented reduction in SRIF concentration in the cerebral cortex in patients with Alzheimer's disease have served as an impetus for studies of this peptide's neurobiological role in the brain. These studies were designed to evaluate the efficacy of centrally administered cysteamine (CYS) as a tool to deplete SRIF in the hypothalamus (HYP) and extrahypothalamic brain areas. Somatostatin was measured by RIA in the frontal cortex (COR), hippocampus (HIP), and HYP in rats after seven daily infusions of CYS into unilateral cannulae stereotaxically positioned into either the lateral ventricle (LV; 300 micrograms/2 microliters) or the dorsal HIP (100 micrograms/2 microliters), and after single (300 mg/kg) or daily (100 mg/kg) sc injections; rats were killed 4 or 24 h after the last injection. After LV infusions, the SRIF concentration was significantly reduced only in the HYP (35% at 4 h and 27% at 24 h). After HIP infusions, the SRIF concentration was significantly reduced only in the HYP at 4 h (23%); no reductions were observed at 24 h. Both a single and repeated sc administrations of CYS reduced SRIF in the HYP only 24 h after treatment (54% and 50%, respectively). Acute sc CYS reduced SRIF in the COR (23%) and the HYP (29%) 4 h after treatment; repeated sc CYS reduced SRIF in the COR (25%) and the HYP (63%). Although the reduction of SRIF in the HYP was increased by repeated sc dosing, the reduction of extrahypothalamic SRIF by sc CYS was relatively small in magnitude and was not enhanced by repeated dosing. These results suggest that CYS is not an ideal tool for depletion of extrahypothalamic SRIF after sc or CNS administration and, moreover, raise serious questions about studies in which behavioral or endocrine alterations after CYS treatment were attributed to specific actions on SRIF-containing neurons.

  8. Micro topography of different material surface by solid abrasive lapped at high speed

    NASA Astrophysics Data System (ADS)

    Tian, Chunlin; Yang, Jiandong; Fan, Jingfeng; Zhou, Huawen

    2007-12-01

    The principle of solid abrasives lapping is that the abrasives are fixed and made into a special lapping tool; the workpiece is lapped in high speed lapping machine tool. It possesses many advantages compared with traditional low speed lapping with particulate abrasives, e.g. high machining efficiency, low machining cost, high and stable machining accuracy. So the highly efficient lapping method has been paid close attention to. This paper made a study on surface micro topography of different material by solid abrasive lapped at high speed. In experiments the lapping technique parameter is fixed, and different workpiece which are made by T10 steel, carbide, ceramic glass and alumina ceramics are lapped. The surface micro topography is measured by SEM, from the measuring result, it can be known that there is some shallow scribe on the surface of T10 steel, and the obvious plastic deformation can be observed. The SEM pictures show that there is some scribe on the surface of ceramics glass after lapped, with more magnification times many micro cracking and some plastic hump can be observed on the scribe. These scribes and humps are first cause of depressing surface quality, and these micro cracking can result in a lot of diffuse reflection on workpiece surface, it decreases the glossiness of mirror surface. On the surface of alumina ceramics there are a lot of defects, the size of such defect is more than the scribe of abrasive, it can be sure that the defect is not produced by lapping, so the material quality is an important effect fact to surface macro topography. On the surface of carbide there are a little of scribe and air cavity, and the scribe is very shallow; the defect of powder metallurgy martial is the primary reason.

  9. Raman study of diamond-based abrasives, and possible artefacts in detecting UHP microdiamond

    NASA Astrophysics Data System (ADS)

    Nasdala, Lutz; Steger, Simon; Reissner, Claudia

    2016-11-01

    Raman spectral characteristics of a range of diamond-based abrasives (powders and sprays) and drilling and cutting tools, originating from preparation laboratories worldwide, are presented. Some abrasives show strong broadening of the main diamond band [FWHM (full width at half band-maximum) > 5 cm- 1] accompanied by strong band-downshift (ν˜ = 1316-1330 cm- 1). Others are characterised by moderate band broadening (FWHM = 1.8-5 cm- 1) at rather regular band position (ν˜ = 1331-1333 cm- 1). In addition we found that a ;fresh; abrasive and its used analogue may in some cases show vast differences in their Raman spectra. The Raman parameters of diamond-based abrasives overlap widely with Raman parameters of UHP (ultra-high pressure) microdiamond. It is hence impossible to assign diamond detected in a geological specimen to either an introduced artefact or a genuine UHP relict, from the Raman spectrum alone. Raman is an excellent technique for the detection of minute amounts of diamond; however it does not provide conclusive evidence for the identification of UHP microdiamond. The latter requires thorough verification, for instance by optical microscopy or, if doubts cannot be dispelled, transmission electron microscopy.

  10. 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.

  11. 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

  12. 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.

  13. Low stress abrasive wear behavior of a hardfaced steel

    NASA Astrophysics Data System (ADS)

    Dasgupta, R.; Prasad, B. K.; Jha, A. K.; Modi, O. P.; Das, S.; Yegneswaran, A. H.

    1998-04-01

    A plain carbon steel was overlayed with a wear-resistant hardfacing alloy by manual arc welding. Low stress abrasive wear tests were conducted with an ASTM rubber wheel abrasion tester using crushed silica and as the abrasive medium. The wear rate decreased with sliding distance, and there was an overall improvement in the abrasive wear resistance as a result of overlaying. The wear behavior of the samples has been discussed in terms of microstructural features while the examination of wear surface and subsurface regions provides insight into the wear mechanisms.

  14. Opportunity Leaves a Trail of 'Rat' Holes

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA's Mars Exploration Rover Opportunity's rock abrasion tool, known informally as the 'Rat,' has nibbled seven holes into the slope of 'Endurance Crater.' This image from the rover's navigation camera was released previously (PIA06716) without the Rat holes labeled so that viewers could try to find the holes themselves. Here, the holes have been identified. Starting from the uppermost pictured (closest to the crater rim) to the lowest, the Rat hole targets are: 'Tennessee,' 'Cobblehill,' 'Virginia,' 'London,' 'Grindstone,' 'Kettlestone,' and 'Drammensfjorden.' These holes were drilled on sols 138 (June 13, 2004), 143 (June 18), 145 (June 20), 148 (June 23), 151 (June 26), 153 (June 28) and 161 (July 7), respectively. Each hole is 4.5 centimeters (1.8 inches) in diameter.

  15. Robot Tools

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Mecanotron, now division of Robotics and Automation Corporation, developed a quick-change welding method called the Automatic Robotics Tool-change System (ARTS) under Marshall Space Flight Center and Rockwell International contracts. The ARTS system has six tool positions ranging from coarse sanding disks and abrasive wheels to cloth polishing wheels with motors of various horsepower. The system is used by fabricators of plastic body parts for the auto industry, by Texas Instruments for making radar domes, and for advanced composites at Aerospatiale in France.

  16. Controlled toothbrush abrasion of softened human enamel.

    PubMed

    Voronets, J; Jaeggi, T; Buergin, W; Lussi, A

    2008-01-01

    The aim of this in vitro study was to compare toothbrush abrasion of softened enamel after brushing with two (soft and hard) toothbrushes. One hundred and fifty-six human enamel specimens were indented with a Knoop diamond. Salivary pellicle was formed in vitro over a period of 3 h. Erosive lesions were produced by means of 1% citric acid. A force-measuring device allowed a controlled toothbrushing force of 1.5 N. The specimens were brushed either in toothpaste slurry or with toothpaste in artificial saliva for 15 s. Enamel loss was calculated from the change in indentation depth of the same indent before and after abrasion. Mean surface losses (95% CI) were recorded in ten treatment groups: (1) soft toothbrush only [28 (17-39) nm]; (2) hard toothbrush only [25 (16-34) nm]; (3) soft toothbrush in Sensodyne MultiCare slurry [46 (27-65) nm]; (4) hard toothbrush in Sensodyne MultiCare slurry [45 (24-66) nm]; (5) soft toothbrush in Colgate sensation white slurry [71 (55-87) nm]; (6) hard toothbrush in Colgate sensation white slurry [85 (60-110) nm]; (7) soft toothbrush with Sensodyne MultiCare [48 (39-57) nm]; (8) hard toothbrush with Sensodyne MultiCare [40 (29-51) nm]; (9) soft toothbrush with Colgate sensation white [51 (37-65) nm]; (10) hard toothbrush with Colgate sensation white [52 (36-68) nm]. Neither soft nor hard toothbrushes produced significantly different toothbrush abrasion of softened human enamel in this model (p > 0.05).

  17. [Temperature measurements during abrasive water jet osteotomy].

    PubMed

    Schmolke, S; Pude, F; Kirsch, L; Honl, M; Schwieger, K; Krömer, S

    2004-01-01

    Working on bone is a major aspect of orthopaedic surgery. Despite its well-known appreciable thermal effects on the edges of the bone cut, the oscillating bone saw blade the oscillating saw remains the standard instrument both for cutting long bones and creating a bed for an endoprosthesis. The application of abrasive water jets offers the possibility of achieving an extremely precise curved cut in bone with no accompanying thermal effect. The thermographically measured absolute temperature increase at the cut edges seen with the water jet was 13 K maximum. The small process forces permit the application in automated handling systems.

  18. 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.

  19. Color View of a 'Rat' Hole Trail Inside 'Endurance'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This view from the Mars Exploration Rover Opportunity's panoramic camera is an approximately true color rendering of the first seven holes that the rover's rock abrasion tool dug on the inner slope of 'Endurance Crater.' The rover was about 12 meters (about 39 feet) down into the crater when it acquired the images combined into this mosaic. The view is looking back toward the rim of the crater, with the rover's tracks visible. The tailings around the holes drilled by the rock abrasion tool, or 'Rat,' show evidence for fine-grained red hematite similar to what was observed months earlier in 'Eagle Crater' outcrop holes.

    Starting from the uppermost pictured (closest to the crater rim) to the lowest, the rock abrasion tool hole targets are called 'Tennessee,' 'Cobblehill,' 'Virginia,' 'London,' 'Grindstone,' 'Kettlestone,' and 'Drammensfjorden.' Opportunity drilled these holes on sols 138 (June 13, 2004), 143 (June 18), 145 (June 20), 148 (June 23), 151 (June 26), 153 (June 28) and 161 (July 7), respectively. Each hole is 4.5 centimeters (1.8 inches) in diameter.

    This image was generated using the panoramic camera's 750-, 530-, and 430-nanometer filters. It was taken on sol 173 (July 19).

  20. Stochastic simplified modelling of abrasive waterjet footprints

    PubMed Central

    Torrubia, P. Lozano; Axinte, D. A.

    2016-01-01

    Abrasive micro-waterjet processing is a non-conventional machining method that can be used to manufacture complex shapes in difficult-to-cut materials. Predicting the effect of the jet on the surface for a given set of machine parameters is a key element of controlling the process. However, the noise of the process is significant, making it difficult to design reliable jet-path strategies that produce good quality parts via controlled-depth milling. The process is highly unstable and has a strong random component that can affect the quality of the workpiece, especially in the case of controlled-depth milling. This study describes a method to predict the variability of the jet footprint for different jet feed speeds. A stochastic partial differential equation is used to describe the etched surface as the jet is moved over it, assuming that the erosion process can be divided into two main components: a deterministic part that corresponds to the average erosion of the jet and a stochastic part that accounts for the noise generated at different stages of the process. The model predicts the variability of the trench profiles to within less than 8%. These advances could enable abrasive micro-waterjet technology to be a suitable technology for controlled-depth milling. PMID:27118905

  1. 2-D protein maps of rat gastrocnemius and soleus muscles: a tool for muscle plasticity assessment.

    PubMed

    Gelfi, Cecilia; Viganò, Agnese; De Palma, Sara; Ripamonti, Marilena; Begum, Shajna; Cerretelli, Paolo; Wait, Robin

    2006-01-01

    Functional characterization of muscle fibers relies on ATPase activity and on differential measurements of metabolic proteins, including mitochondrial and glycolytic enzymes, glucose, lactate and lactic acid transporters, calcium cycling proteins and components of the contractile machinery. The recent introduction of microarray technology has enabled detailed gene expression studies under different physiological and pathological conditions, thus generating novel hypotheses on muscle function. However, microarray approaches are limited by the incomplete genome coverage of currently available chips, and by poor correlation between mRNA concentration and protein expression level. We have used 2-DE and MS to build a reference map of proteins from rat mixed gastrocnemius and soleus muscle, and to assess qualitative and quantitative differences in protein distribution between these two functionally dissimilar muscles. More than 800 spots on each gel were detected by silver staining, of which 167 were excised, digested in-gel with trypsin and analyzed by ESI-MS/MS. One hundred and twenty eight distinct gene products were identified, including metabolic, transport and contractile proteins. Forty one spots displayed differences in relative expression level between mixed gastrocnemius and soleus samples. These data not only enable differentiation of functionally distinct slow-twitch and fast-twitch fiber types, but also provide tools for investigating muscle plasticity in response to physiological and environmental conditions such as aging or hypoxia.

  2. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.215 Abrasive wheel machinery. (a) General requirements—(1) Machine guarding. Abrasive wheels shall be used only on machines provided with... omitted; and (ii) The spindle end, nut, and outer flange may be exposed on machines designed as...

  3. 7 CFR 3201.66 - Cuts, burns, and abrasions ointments.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Cuts, burns, and abrasions ointments. 3201.66 Section... PROCUREMENT Designated Items § 3201.66 Cuts, burns, and abrasions ointments. (a) Definition. Products designed..., in accordance with this part, will give a procurement preference for qualifying biobased cuts,...

  4. 7 CFR 3201.66 - Cuts, burns, and abrasions ointments.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Cuts, burns, and abrasions ointments. 3201.66 Section... PROCUREMENT Designated Items § 3201.66 Cuts, burns, and abrasions ointments. (a) Definition. Products designed..., in accordance with this part, will give a procurement preference for qualifying biobased cuts,...

  5. 7 CFR 3201.66 - Cuts, burns, and abrasions ointments.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Cuts, burns, and abrasions ointments. 3201.66 Section... PROCUREMENT Designated Items § 3201.66 Cuts, burns, and abrasions ointments. (a) Definition. Products designed..., in accordance with this part, will give a procurement preference for qualifying biobased cuts,...

  6. 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.

  7. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Section 872.6030 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... that contains an abrasive material, such as silica pumice, intended to remove debris from the teeth. The abrasive polish is applied to the teeth by a handpiece attachment (prophylaxis cup)....

  8. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Section 872.6030 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... that contains an abrasive material, such as silica pumice, intended to remove debris from the teeth. The abrasive polish is applied to the teeth by a handpiece attachment (prophylaxis cup)....

  9. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Section 872.6030 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... that contains an abrasive material, such as silica pumice, intended to remove debris from the teeth. The abrasive polish is applied to the teeth by a handpiece attachment (prophylaxis cup)....

  10. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Section 872.6030 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... that contains an abrasive material, such as silica pumice, intended to remove debris from the teeth. The abrasive polish is applied to the teeth by a handpiece attachment (prophylaxis cup)....

  11. LANL12-RS-107J PYTHON Radiography Analysis Tool (PyRAT). Mid-Year Deliverable Report for FY15

    SciTech Connect

    Temple, Brian Allen; Armstrong, Jerawan Chudoung

    2015-04-14

    This document is a mid-year report on a deliverable for the PYTHON Radiography Analysis Tool (PyRAT) for project LANL12-RS-107J in FY15. The deliverable is deliverable number 2 in the work package and is titled “Add the ability to read in more types of image file formats in PyRAT”. Right now PyRAT can only read in uncompressed TIF files (tiff files). It is planned to expand the file formats that can be read by PyRAT, making it easier to use in more situations. A summary of the file formats added include jpeg, jpg, png and formatted ASCII files.

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

    NASA Astrophysics Data System (ADS)

    Doğan, Ö. N.; Hawk, J. A.; Laird, G.

    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.

  13. Cerebral salt wasting in subarachnoid hemorrhage rats: model, mechanism, and tool.

    PubMed

    Kojima, Jun; Katayama, Yoichi; Moro, Nobuhiro; Kawai, Hiroyuki; Yoneko, Maki; Mori, Tatsuro

    2005-04-01

    Cerebral salt wasting (CSW) frequently occurs concomitantly with aneurysmal subarachnoid hemorrhage (SAH). CSW induces excessive natriuresis and osmotic diuresis, and reduces total blood volume. As a result, the risk of symptomatic cerebral vasospasm may be elevated. Therefore, it is important to determine the mechanism of CSW. The purpose of this study was to evaluate whether the rat SAH model exhibits CSW and to investigate the relationship between CSW and natriuretic peptides. A SAH model was produced in 24 rats by perforating a cerebral artery with a nylon thread up through the common carotid artery. To evaluate CSW, urine was cumulatively collected from SAH onset to 12 hours and sodium (Na) excretion was analyzed. Body weight and hematocrit were analyzed before and after SAH onset. Concentrations of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in plasma were also analyzed. Urine volume and total Na excretion of SAH rats were significantly higher than those of sham rats (p<0.05). Body weight of SAH rats significantly decreased and hematocrit significantly increased (p < 0.05). ANP concentration was significantly decreased in SAH rats (p<0.05). However, BNP concentrations did not change. This study demonstrated for the first time that a rat SAH model exhibited CSW. It was suggested that the cause of CSW was neither ANP nor BNP. In addition, this rat SAH model will be useful for study of CSW after SAH.

  14. 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.

  15. Transgenic rats with green, red, and blue fluorescence: powerful tools for bioimaging, cell trafficking, and differentiation

    NASA Astrophysics Data System (ADS)

    Murakami, Takashi; Kobayashi, Eiji

    2005-04-01

    The rat represents a perfect animal for broadening medical experiments, because its physiology has been well understood in the history of experimental animals. In addition, its larger body size takes enough advantage for surgical manipulation, compared to the mouse. Many rat models mimicking human diseases, therefore, have been used in a variety of biomedical studies including physiology, pharmacology, transplantation, and immunology. In an effort to create the specifically designed rats for biomedical research and regenerative medicine, we have developed the engineered rat system on the basis of transgenic technology and succeeded in establishing various transgenic rat strains. The transgenic rats with green fluorescent protein (GFP) were generated in the two different strains (Wistar and Lewis), in which GFP is driven under the chicken beta-actin promoter and cytomegalovirus enhancer (CAG promoter). Their GFP expression levels were different in each organ, but the Lewis line expressed GFP strongly and ubiquitously in most of the organs compared with that of Wistar. For red fluorescence, DsRed2 was transduced to the Wistar rats: one line specifically expresses DsRed2 in the liver under the mouse albumin promoter, another is designed for the Cre/LoxP system as the double reporter rat (the initial DsRed2 expression turns on GFP in the presence of Cre recombinase). LacZ-transgenic rats represent blue color, and LacZ is driven the CAG (DA) or ROSA26 promoter (Lewis). Our unique transgenic rats" system highlights the powerful performance for the elucidation of many cellular processes in regenerative medicine, leading to innovative medical treatments.

  16. 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.

  17. Abrasive Wear Performance of Aluminium Modified Epoxy-Glass Fiber Composites

    NASA Astrophysics Data System (ADS)

    Kamble, Vikram G.; Mishra, Punyapriya; Al Dabbas, Hassan A.; Panda, H. S.; Fernandez, Johnathan Bruce

    2015-07-01

    For a long time, Aluminum filled epoxies molds have been used in rapid tooling process. These molds are very economical when applied in manufacturing of low volume of plastic parts. To improve the thermal conductivity of the material, the metallic filler material is added to it and the glass fiber improves the wear resistance of the material. These two important parameters establish the life of composites. The present work reports on abrasive wear behavior of Aluminum modified epoxy and glass fiber composite with 5 wt.% and 10 wt.% of aluminum particles. Through pin on disc wear testing machine, we studied the wear behaviors of composites, and all these samples were fabricated by using hand layup process. Epoxy resin was used as matrix material which was reinforced with Glass fiber and Aluminum as filler. The composite with 5 wt.% and 10 wt.% of Al was cast with dimensions 100 × 100 × 6 mm. The specimens were machined to a size of 6 × 6 × 4 mm for abrasive testing. Abrasive tests were carried out for different grit paper sizes, i.e., 150, 320, 600 at different sliding distance, i.e., 20, 40, 60 m at different loads of 5, 10 and 15 N and at constant speed. The weight loss due to wear was calculated along with coefficient of friction. Hardness was found using Rockwell hardness machine. The SEM morphology of the worn out surface wear was analyzed to understand the wear mechanism. Results showed that the addition of Aluminum particles was beneficial for low abrasive conditions.

  18. Performance analysis of cutting graphite-epoxy composite using a 90,000psi abrasive waterjet

    NASA Astrophysics Data System (ADS)

    Choppali, Aiswarya

    Graphite-epoxy composites are being widely used in many aerospace and structural applications because of their properties: which include lighter weight, higher strength to weight ratio and a greater flexibility in design. However, the inherent anisotropy of these composites makes it difficult to machine them using conventional methods. To overcome the major issues that develop with conventional machining such as fiber pull out, delamination, heat generation and high tooling costs, an effort is herein made to study abrasive waterjet machining of composites. An abrasive waterjet is used to cut 1" thick graphite epoxy composites based on baseline data obtained from the cutting of ¼" thick material. The objective of this project is to study the surface roughness of the cut surface with a focus on demonstrating the benefits of using higher pressures for cutting composites. The effects of major cutting parameters: jet pressure, traverse speed, abrasive feed rate and cutting head size are studied at different levels. Statistical analysis of the experimental data provides an understanding of the effect of the process parameters on surface roughness. Additionally, the effect of these parameters on the taper angle of the cut is studied. The data is analyzed to obtain a set of process parameters that optimize the cutting of 1" thick graphite-epoxy composite. The statistical analysis is used to validate the experimental data. Costs involved in the cutting process are investigated in term of abrasive consumed to better understand and illustrate the practical benefits of using higher pressures. It is demonstrated that, as pressure increased, ultra-high pressure waterjets produced a better surface quality at a faster traverse rate with lower costs.

  19. 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.

  20. Interaction between attrition,abrasion and erosion in tooth wear.

    PubMed

    Addy, M; Shellis, R P

    2006-01-01

    Tooth wear is the result of three processes: abrasion (wear produced by interaction between teeth and other materials), attrition (wear through tooth-tooth contact) and erosion (dissolution of hard tissue by acidic substances). A further process (abfraction) might potentiate wear by abrasion and/or erosion. Both clinical and experimental observations show that individual wear mechanisms rarely act alone but interact with each other. The most important interaction is the potentiation of abrasion by erosive damage to the dental hard tissues. This interaction seems to be the major factor in occlusal and cervical wear. The available evidence seems insufficient to establish whether abfraction is an important contributor to tooth wear in vivo. Saliva can modulate erosive/abrasive tooth wear through formation of pellicle and by remineralisation but cannot prevent it.

  1. The interactions between attrition, abrasion and erosion in tooth wear.

    PubMed

    Shellis, R Peter; Addy, Martin

    2014-01-01

    Tooth wear is the result of three processes: abrasion (wear produced by interaction between teeth and other materials), attrition (wear through tooth-tooth contact) and erosion (dissolution of hard tissue by acidic substances). A further process (abfraction) might potentiate wear by abrasion and/or erosion. Knowledge of these tooth wear processes and their interactions is reviewed. Both clinical and experimental observations show that individual wear mechanisms rarely act alone but interact with each other. The most important interaction is the potentiation of abrasion by erosive damage to the dental hard tissues. This interaction seems to be the major factor in occlusal and cervical wear. The available evidence is insufficient to establish whether abfraction is an important contributor to tooth wear in vivo. Saliva can modulate erosive/abrasive tooth wear, especially through formation of pellicle, but cannot prevent it.

  2. 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... excessive restorative materials, such as gold, and to smooth rough surfaces from oral restorations, such...

  3. 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... excessive restorative materials, such as gold, and to smooth rough surfaces from oral restorations, such...

  4. Application of Mathematical Modelling as a Tool to Analyze the EEG Signals in Rat Model of Focal Cerebral Ischemia

    NASA Astrophysics Data System (ADS)

    Paul, S.; Bhattacharya, P.; Pandey, A. K.; Patnaik, R.

    2014-01-01

    The present paper envisages the application of mathematical modelling with the autoregressive (AR) model method as a tool to analyze electroencephalogram data in rat subjects of transient focal cerebral ischemia. This modelling method was used to determine the frequencies and characteristic changes in brain waveforms which occur as a result of disorders or fluctuating physiological states. This method of analysis was utilized to ensure actual correlation of the different mathematical paradigms. The EEG data was obtained from different regions of the rat brain and was modelled by AR method in a MATLAB platform. AR modelling was utilized to study the long-term functional outcomes of a stroke and also is preferable for EEG signal analysis because the signals consist of discrete frequency intervals. Modern spectral analysis, namely AR spectrum analysis, was used to correlate the conditional and prevalent changes in brain function in response to a stroke.

  5. 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.

  6. Surface quality control in diamond abrasive finishing

    NASA Astrophysics Data System (ADS)

    Filatov, Yuriy D.; Sidorko, Volodymyr I.; Filatov, Olexandr Yu.; Yaschuk, Vasil P.; Heisel, Uwe; Storchak, Michael

    2009-06-01

    The paper presents a procedure for measuring laser radiation reflection and scattering coefficients of polished surface. A relation between the scattered light intensity and the polished surface roughness is studied. It is demonstrated that colorimetric characteristics of non-metallic materials can be determined from the light scattering and reflection coefficients. This work has demonstrated a possibility of and created prerequisites for the development of an express method for tentative assessment of polished surface roughness. Of interest is the use of the β(Rz) function for the purposes of quality inspection of polished surfaces of natural and synthetic stone and other non-metallic materials. It was established that the most relevant parameter of roughness, which can be defined by the light reflection is Rz. The Dependency of the reflection factor from parameter of roughness Rz was approximated by formula with inaccuracy 5-10%. Inaccuracy of the determination of roughness Rz has formed 1%. It was shown that method of the surface roughness control using the light reflection factor is the most efficient for surfaces with roughness Rz <0.3 microns, typical for finish diamond-abrasive machining.

  7. Abrasive-waterjet machining of isogrid structures

    NASA Astrophysics Data System (ADS)

    Hashish, Mohamed; Marvin, Mark; Monserud, David

    1990-12-01

    An experimental investigation was conducted to determine the feasibility of machining isogrid structures with abrasive-waterjets (AWJs). The main objective was to mill isogrid patterns in surfaces with accurate depth control using an AWJ. Three different approaches using AWJs were tested: linear cutting of isogrid patterns for diffusion bonding, milling with conventional AWJ nozzles, and milling with a single-angled rotary AWJ nozzle. It was shown that pocket milling with conventional AWJs is the most feasible of those tested. The milling can be done internally on preformed aluminum tubes, and the AWJ can also be used on materials other than aluminum. Accurate depth control can be achieved at high productivity rates. As an example, it is projected that a 48-inch-diameter skirt 12 inches high could be milled with an isogrid pattern in 6.3 hours. Milled isogrid patterns can be controlled to 0.001 inch, and thin walls of less than 0.025 inch are achievable. Milling isogrid patterns with conventional AWJs could be very economical, but additional development efforts are required to optimize the milling process and to demonstrate the milling of prototype parts.

  8. Dynamical simulation of an abrasive wear process

    NASA Astrophysics Data System (ADS)

    Elalem, Khaled; Li, D. Y.

    1999-05-01

    A dynamic computer model was developed to simulate wear behavior of materials on micro-scales. In this model, a material system is discretized and mapped onto a lattice or grid. Each lattice site represents a small volume of the material. During a wear process, a lattice site may move under the influence of external force and the interaction between the site and its adjacent sites. The site-site interaction is a function of mechanical properties of the material such as the elastic modulus, yield strength, work hardening and the fracture strain. Newton's law of motion is used to determine the movement of lattice sites during a wear process. The strain between a pair of sites is recoverable if it is within the elastic deformation range; otherwise plastic deformation takes place. A bond between two adjacent sites is broken when its strain exceeds a critical value. A site or a cluster of sites is worn away if all bonds connecting the site or the cluster to its nearest neighbors are broken. The model well describes the strain distribution in a contact region, in consistence with a finite element analysis. This model was applied to several metallic materials abraded under the ASTM G65 abrasion condition, and the results were compared to experimental observations. Good agreement between the modeling and the experiment was found.

  9. 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.

  10. 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.

  11. Draft De Novo Transcriptome of the Rat Kangaroo Potorous tridactylus as a Tool for Cell Biology

    PubMed Central

    Udy, Dylan B.; Voorhies, Mark; Chan, Patricia P.; Lowe, Todd M.; Dumont, Sophie

    2015-01-01

    The rat kangaroo (long-nosed potoroo, Potorous tridactylus) is a marsupial native to Australia. Cultured rat kangaroo kidney epithelial cells (PtK) are commonly used to study cell biological processes. These mammalian cells are large, adherent, and flat, and contain large and few chromosomes—and are thus ideal for imaging intra-cellular dynamics such as those of mitosis. Despite this, neither the rat kangaroo genome nor transcriptome have been sequenced, creating a challenge for probing the molecular basis of these cellular dynamics. Here, we present the sequencing, assembly and annotation of the draft rat kangaroo de novo transcriptome. We sequenced 679 million reads that mapped to 347,323 Trinity transcripts and 20,079 Unigenes. We present statistics emerging from transcriptome-wide analyses, and analyses suggesting that the transcriptome covers full-length sequences of most genes, many with multiple isoforms. We also validate our findings with a proof-of-concept gene knockdown experiment. We expect that this high quality transcriptome will make rat kangaroo cells a more tractable system for linking molecular-scale function and cellular-scale dynamics. PMID:26252667

  12. Draft De Novo Transcriptome of the Rat Kangaroo Potorous tridactylus as a Tool for Cell Biology.

    PubMed

    Udy, Dylan B; Voorhies, Mark; Chan, Patricia P; Lowe, Todd M; Dumont, Sophie

    2015-01-01

    The rat kangaroo (long-nosed potoroo, Potorous tridactylus) is a marsupial native to Australia. Cultured rat kangaroo kidney epithelial cells (PtK) are commonly used to study cell biological processes. These mammalian cells are large, adherent, and flat, and contain large and few chromosomes-and are thus ideal for imaging intra-cellular dynamics such as those of mitosis. Despite this, neither the rat kangaroo genome nor transcriptome have been sequenced, creating a challenge for probing the molecular basis of these cellular dynamics. Here, we present the sequencing, assembly and annotation of the draft rat kangaroo de novo transcriptome. We sequenced 679 million reads that mapped to 347,323 Trinity transcripts and 20,079 Unigenes. We present statistics emerging from transcriptome-wide analyses, and analyses suggesting that the transcriptome covers full-length sequences of most genes, many with multiple isoforms. We also validate our findings with a proof-of-concept gene knockdown experiment. We expect that this high quality transcriptome will make rat kangaroo cells a more tractable system for linking molecular-scale function and cellular-scale dynamics.

  13. 3D He-3 diffusion MRI as a local in vivo morphometric tool to evaluate emphysematous rat lungs

    SciTech Connect

    Jacob, Rick E.; Minard, Kevin R.; Laicher, Gernot J.; Timchalk, Charles

    2008-08-21

    In this work, we validate 3He magnetic resonance imaging as a non-invasive morphometric tool to assess emphysematous disease state on a local level. Emphysema was induced intratracheally in rats with 25U/100g body weight of porcine pancreatic elastase dissolved in 200 μL saline. Rats were then paired with saline-dosed controls. Nine three-dimensional 3He diffusion-weighted images were acquired at one-, two-, or three-weeks post-dose, after which the lungs were harvested and prepared for histological analysis. Recently introduced indices sensitive to the heterogeneity of the airspace size distribution were calculated. These indices, D1 and D2, were derived from the moments of the mean equivalent airway diameters. Averaged over the entire lung, it is shown that the 3He diffusivity (Dave) and anisotropy (Dan) both correlate with histology (R = 0.85, p < 0.0001 and R = 0.88, p < 0.0001, respectively). By matching small (0.046 cm2) regions in 3He images with corresponding regions in histological slices, Dave and Dan each correlate significantly with both D1 and D2 (R = 0.93, p < 0.0001). It is concluded that 3He MRI is a viable non-invasive morphometric tool for localized in vivo emphysema assessment.

  14. Pebble and bedrock abrasion during fluvial transport in active orogenic setting : experimental study and application to natural hydrographic networks.

    NASA Astrophysics Data System (ADS)

    Attal, M.; Lavé, J.

    2003-04-01

    At mountain range scale, rivers play an important role in shaping the landscape : in response to active uplift, they incise into bedrock and ensure base level lowering for hillslopes erosion. At the same time, they ensure evacuation of erosion products out of the range as suspended- or bedload. Incision rates are commonly equated with a stream power law, assuming that river incision depends only on hydrodynamic variables. However, this simplification is not mechanically satisfying : in many settings, river bedload fluxes exert an important control on incision rates, by limiting bedrock exposure or by providing an efficient tool for river mechanical abrasion. It is therefore important to better quantify the abrasion processes during bedload transport both to deduce pebble size reduction that controls carrying capacity and bedrock exposure, and to derive bedrock incision laws. Such characterization can be constrained through experimental studies or field measurements. Experimental studies on pebble and bedrock abrasion have been conducted for a long time [e.g. Daubree, 1879]. They generally provide incision rates around two orders of magnitude below natural downstream fining rates. Previous authors have suggested that this discrepancy could be explained by the fact that experimental device doesn’t reproduce really the abrasion phenomena effective in natural rivers, like saltation and following impacts. In this way, we have built an experimental device in order to reproduce these abrasion phenomena. It consists of a circular flume of 30 cm width and of 60 cm curvature radius. Water is injected tangentially on four points ; it generates a flow that produce sediment motion. Velocity vertical profile is roughly similar to what could be observed in natural rivers. The bottom and the sides of the device are interchangeable, in order to measure distinctly pebble abrasion or the interactions between sediment load and substratum. The aim of this experimental study is to

  15. 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.

  16. 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.

  17. Aeolian abrasion on Venus: Preliminary results from the Venus simulator

    NASA Technical Reports Server (NTRS)

    Marshall, J. R.; Greeley, Ronald; Tucker, D. W.; Pollack, J. B.

    1987-01-01

    The role of atmospheric pressure on aeolian abrasion was examined in the Venus Simulator with a constant temperature of 737 K. Both the rock target and the impactor were fine-grained basalt. The impactor was a 3 mm diameter angular particle chosen to represent a size of material that is entrainable by the dense Venusian atmosphere and potentially abrasive by virtue of its mass. It was projected at the target 10 to the 5 power times at a velocity of 0.7 m/s. The impactor showed a weight loss of approximately 1.2 x 10 to the -9 power gm per impact with the attrition occurring only at the edges. Results from scanning electron microscope analysis, profilometry, and weight measurement are summarized. It is concluded that particles can incur abrasion at Venusian temperatures even with low impact velocities expected for Venus.

  18. Antibacterial photodynamic therapy with 808-nm laser and indocyanine green on abrasion wound models

    NASA Astrophysics Data System (ADS)

    Topaloglu, Nermin; Güney, Melike; Yuksel, Sahru; Gülsoy, Murat

    2015-02-01

    Infections with pathogens could cause serious health problems, such as septicemia and subsequent death. Some of these deaths are caused by nosocomial, chronic, or burn-related wound infections. Photodynamic therapy (PDT) can be useful for the treatment of these infections. Our aim was to investigate the antibacterial effect of indocyanine green (ICG) and 808-nm laser on a rat abrasion wound model infected with the multidrug resistant Staphylococcus aureus strain. Abrasion wounds were infected with a multidrug resistant clinical isolate of S. aureus. ICG concentrations of 500, 1000, and 2000 μg/ml were applied with a 450 J/cm2 energy dose. Temperature change was monitored by a thermocouple system. The remaining bacterial burden was determined by the serial dilution method after each application. Wounds were observed for 11 days posttreatment. The recovery process was assessed macroscopically. Tissue samples were also examined histologically by hematoxylin-eosin staining. Around a 90% reduction in bacterial burden was observed after PDT applications. In positive control groups (ICG-only and laser-only groups), there was no significant reduction. The applied energy dose did not cause any thermal damage to the target tissue or host environment. Results showed that ICG together with a 808-nm laser might be a promising antibacterial method to eliminate infections in animals and accelerate the wound-healing process.

  19. 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.

  20. Results from the RAT Magnet Experiment on Spirit and Opportunity

    NASA Astrophysics Data System (ADS)

    Goetz, Walter; Hviid, S. F.; Madsen, M. B.; Kinch, K. M.; Leer, K.; Gunnlauggson, H. P.

    2006-09-01

    The Rock Abrasion Tool (RAT) is one of the four payload elements that are mounted to the end of the robotic arm onboard the Mars Exploration Rovers (MER). The RAT is a mechanism that can grind circular depressions several millimeters into the Martian rocks. The RAT magnet experiment is composed of four permanent magnets of different strengths built into the revolve housing cap plate of the RAT. Magnetic material liberated by the grinding process will be attracted by these magnets. At Gusev crater 14 different grindings were performed over 416 sols. During grinding into rocks in the plains (Adirondack, Humphrey, Mazatzal) a substantial amount of homogeneous, dark-gray material accumulated on the magnets. Based on data from the Mössbauer (MB) spectrometer the rocks are known to contain the magnetic material (Ti) magnetite. During grindings into the Eagle crater outcrop at Meridiani Planum strongly magnetic material was captured by the RAT magnets. The material is reddish and appears to be largely homogeneous. The total amount of collected material is slightly smaller as compared to the RAT magnet experiment on Spirit. Also no strongly magnetic, iron containing mineral phase has been identified by MB spectroscopy. Based on Pancam observations of the RAT magnets as well as other data we suggest that the Meridiani outcrops contains < 0.5 wt.% of a ferrimagnetic phase, possibly partly oxidized magnetite.

  1. A semi-automated software tool to study treadmill locomotion in the rat: from experiment videos to statistical gait analysis.

    PubMed

    Gravel, P; Tremblay, M; Leblond, H; Rossignol, S; de Guise, J A

    2010-07-15

    A computer-aided method for the tracking of morphological markers in fluoroscopic images of a rat walking on a treadmill is presented and validated. The markers correspond to bone articulations in a hind leg and are used to define the hip, knee, ankle and metatarsophalangeal joints. The method allows a user to identify, using a computer mouse, about 20% of the marker positions in a video and interpolate their trajectories from frame-to-frame. This results in a seven-fold speed improvement in detecting markers. This also eliminates confusion problems due to legs crossing and blurred images. The video images are corrected for geometric distortions from the X-ray camera, wavelet denoised, to preserve the sharpness of minute bone structures, and contrast enhanced. From those images, the marker positions across video frames are extracted, corrected for rat "solid body" motions on the treadmill, and used to compute the positional and angular gait patterns. Robust Bootstrap estimates of those gait patterns and their prediction and confidence bands are finally generated. The gait patterns are invaluable tools to study the locomotion of healthy animals or the complex process of locomotion recovery in animals with injuries. The method could, in principle, be adapted to analyze the locomotion of other animals as long as a fluoroscopic imager and a treadmill are available.

  2. The Sea of Azov: Recent abrasion processes and problems of coastal protection

    NASA Astrophysics Data System (ADS)

    Matishov, G. G.; Bespalova, L. A.; Ivlieva, O. V.; Tsygankova, A. E.; Kropyanko, L. V.

    2016-12-01

    The abrasion processes of the Sea of Azov have been assessed on the basis of long-term monitoring. The coast has been zoned by the degree of abrasion. The current condition of coast protection measures has been studied.

  3. Polishing is made cheaper by disposable diamond-impregnated abrasive cloth

    NASA Technical Reports Server (NTRS)

    Harper, F. J.

    1972-01-01

    Diamond impregnated abrasive cloth eliminated expensive diamond pastes and was economically disposed of to avoid contamination. Cloth was spunbonded nylon, but any napless fabric could be used. Cloth was sprayed with diamond abrasive gel.

  4. The influence of aluminum and carbon on the abrasion resistance of high manganese steels

    NASA Astrophysics Data System (ADS)

    Buckholz, Samuel August

    Abrasive wear testing of lightweight, austenitic Fe-Mn-Al-C cast steel has been performed in accordance with ASTM G65 using a dry sand, rubber wheel, abrasion testing apparatus. Testing was conducted on a series of Fe-30Mn-XAl-YC-1Si-0.5Mo chemistries containing aluminum levels from 2.9 to 9.5 wt.% and carbon levels from 0.9 to 1.83 wt.%. Solution treated materials having an austenitic microstructure produced the highest wear resistance. Wear resistance decreased with higher aluminum, lower carbon, and higher hardness after age hardening. In the solution treated condition the wear rate was a strong function of the aluminum to carbon ratio and the wear rate increased with a parabolic dependence on the Al/C ratio, which ranged from 1.8 to 10.2. Examination of the surface wear scar revealed a mechanism of plowing during abrasion testing and this method of material removal is sensitive to work hardening rate. Work hardening behavior was determined from tensile tests and also decreased with increasing Al/C ratio and after aging hardening. The loss of wear resistance is related to short range ordering of Al and C in the solution treated materials and kappa-carbide precipitation in age hardened materials and both contribute to planar slip and lower work hardening rates. A high carbon tool steel (W1) and a bainitic low alloy steel (SAE 8620) were also tested for comparison. A lightweight steel containing 6.5 wt.% Al and 1.2 wt.% C has wear resistance comparable to within 5% of the bainitic SAE 8620 steel forging currently used for the Bradley Fighting Vehicle track shoe and this cast Fe-Mn-Al-C steel, at equivalent tensile properties, would be 10% lighter.

  5. 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)

  6. Review of Artificial Abrasion Test Methods for PV Module Technology

    SciTech Connect

    Miller, David C.; Muller, Matt T.; Simpson, Lin J.

    2016-08-01

    This review is intended to identify the method or methods--and the basic details of those methods--that might be used to develop an artificial abrasion test. Methods used in the PV literature were compared with their closest implementation in existing standards. Also, meetings of the International PV Quality Assurance Task Force Task Group 12-3 (TG12-3, which is concerned with coated glass) were used to identify established test methods. Feedback from the group, which included many of the authors from the PV literature, included insights not explored within the literature itself. The combined experience and examples from the literature are intended to provide an assessment of the present industry practices and an informed path forward. Recommendations toward artificial abrasion test methods are then identified based on the experiences in the literature and feedback from the PV community. The review here is strictly focused on abrasion. Assessment methods, including optical performance (e.g., transmittance or reflectance), surface energy, and verification of chemical composition were not examined. Methods of artificially soiling PV modules or other specimens were not examined. The weathering of artificial or naturally soiled specimens (which may ultimately include combined temperature and humidity, thermal cycling and ultraviolet light) were also not examined. A sense of the purpose or application of an abrasion test method within the PV industry should, however, be evident from the literature.

  7. False-Color View of a 'Rat' Hole Trail

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This view from the Mars Exploration Rover Opportunity's panoramic camera is a false-color composite rendering of the first seven holes that the rover's rock abrasion tool dug on the inner slope of 'Endurance Crater.' The rover was about 12 meters (about 39 feet) down into the crater when it acquired the images combined into this mosaic. The view is looking back toward the rim of the crater, with the rover's tracks visible. The tailings around the holes drilled by the rock abrasion tool, or 'Rat,' show evidence for fine-grained red hematite similar to what was observed months earlier in 'Eagle Crater' outcrop holes.

    Last week, viewers were asked to try seeing as many holes as they could from a black-and-white, navigation-camera image (PIA06716). Most viewers will find it far easier to see the seven holes in this exaggerated color image; the same is true for scientists who are studying the holes from millions of miles away.

    Starting from the uppermost pictured (closest to the crater rim) to the lowest, the rock abrasion tool hole targets are called 'Tennessee,' 'Cobblehill,' 'Virginia,' 'London,' 'Grindstone,' 'Kettlestone,' and 'Drammensfjorden.' Opportunity drilled these holes on sols 138 (June 13, 2004), 143 (June 18), 145 (June 20), 148 (June 23), 151 (June 26), 153 (June 28) and 161 (July 7), respectively. Each hole is 4.5 centimeters (1.8 inches) in diameter.

    This image was generated using the panoramic camera's 750-, 530-, and 430-nanometer filters. It was taken on sol 173 (July 19).

  8. Brushing abrasion of luting cements under neutral and acidic conditions.

    PubMed

    Buchalla, W; Attin, T; Hellwig, E

    2000-01-01

    Four resin based materials (Compolute Aplicap, ESPE; Variolink Ultra, Vivadent; C&B Metabond, Parkell and Panavia 21, Kuraray), two carboxylate cements (Poly-F Plus, Dentsply DeTrey and Durelon Maxicap, ESPE), two glass-ionomer cements (Fuji I, GC and Ketac-Cem Aplicap, ESPE), one resin-modified glass ionomer cement (Vitremer, 3M) one polyacid-modified resin composite (Dyract Cem, Dentsply DeTrey) and one zinc phosphate cement (Harvard, Richter & Hoffmann) were investigated according to their brushing resistance after storage in neutral and acidic buffer solutions. For this purpose 24 cylindrical acrylic molds were each filled with the materials. After hardening, the samples were stored for seven days in 100% relative humidity and at 37 degrees C. Subsequently, they were ground flat and polished. Then each specimen was covered with an adhesive tape leaving a 4 mm wide window on the cement surface. Twelve samples of each material were stored for 24 hours in a buffer solution with a pH of 6.8. The remaining 12 samples were placed in a buffer with a pH of 3.0. All specimens were then subjected to a three media brushing abrasion (2,000 strokes) in an automatic brushing machine. Storage and brushing were performed three times. After 6,000 brushing strokes per specimen, the tape was removed. Brushing abrasion was measured with a computerized laser profilometer and statistically analyzed with ANOVA and Tukey's Standardized Range Test (p < or = 0.05). The highest brushing abrasion was found for the two carboxylate cements. The lowest brushing abrasion was found for one resin based material, Compolute Aplicap. With the exception of three resin-based materials, a lower pH led to a higher brushing abrasion.

  9. Brushing abrasion of eroded bovine enamel pretreated with topical fluorides.

    PubMed

    Vieira, A; Lugtenborg, M; Ruben, J L; Huysmans, M C D N J M

    2006-01-01

    Topical fluorides have been proposed for the prevention of erosive dental wear. This study evaluated the in vitro effect of a single professional application of 4% titanium tetrafluoride (TiF4), 1% amine fluoride (AmF) and 0.1% difluorosilane varnish (FV) in preventing wear due to combined erosion and brushing abrasion. One hundred and eight bovine enamel samples were used. Control groups were not pretreated with any product (C), pretreated with a fluoride-free varnish (FV-bl) or pretreated with fluoride varnish and subsequently submitted to varnish removal (FV-r). Wear was modeled by submitting the fluoride-treated and control groups to 3 cycles of the following regimens: erosion/remineralization (er/remin), abrasion/remineralization (abr/remin) or erosion/abrasion/remineralization (er/abr/remin). Erosion was simulated by immersion of the samples for 10 min in citric acid 50 mM (pH 3). Abrasion was carried out for 1 min (200 strokes, load 150 g) in a wear device. Remineralization (2 h artificial saliva) took place between the cycles. Two-way ANOVA showed that there was a significant interaction (pabrasion in vitro.

  10. Wear characterization of abrasive waterjet nozzles and nozzle materials

    NASA Astrophysics Data System (ADS)

    Nanduri, Madhusarathi

    Parameters that influence nozzle wear in the abrasive water jet (AWJ) environment were identified and classified into nozzle geometric, AWJ system, and nozzle material categories. Regular and accelerated wear test procedures were developed to study nozzle wear under actual and simulated conditions, respectively. Long term tests, using garnet abrasive, were conducted to validate the accelerated test procedure. In addition to exit diameter growth, two new measures of wear, nozzle weight loss and nozzle bore profiles were shown to be invaluable in characterizing and explaining the phenomena of nozzle wear. By conducting nozzle wear tests, the effects of nozzle geometric, and AWJ system parameters on nozzle wear were systematically investigated. An empirical model was developed for nozzle weight loss rate. To understand the response of nozzle materials under varying AWJ system conditions, erosion tests were conducted on samples of typical nozzle materials. The effect of factors such as jet impingement angle, abrasive type, abrasive size, abrasive flow rate, water pressure, traverse speed, and target material was evaluated. Scanning electron microscopy was performed on eroded samples as well as worn nozzles to understand the wear mechanisms. The dominant wear mechanism observed was grain pullout. Erosion models were reviewed and along the lines of classical erosion theories a semi-empirical model, suitable for erosion of nozzle materials under AWJ impact, was developed. The erosion data correlated very well with the developed model. Finally, the cutting efficiency of AWJ nozzles was investigated in conjunction with nozzle wear. The cutting efficiency of a nozzle deteriorates as it wears. There is a direct correlation between nozzle wear and cutting efficiency. The operating conditions that produce the most efficient jets also cause the most wear in the nozzle.

  11. Loose abrasive lapping hardness of optical glasses and its interpretation.

    PubMed

    Lambropoulos, J C; Xu, S; Fang, T

    1997-03-01

    We present an interpretation of the lapping hardness of commercially available optical glasses in terms of a micromechanics model of material removal by subsurface lateral cracking. We analyze data on loose abrasive microgrinding, or lapping at fixed nominal pressure, for many commercially available optical glasses in terms of this model. The Schott and Hoya data on lapping hardness are correlated with the results of such a model. Lapping hardness is a function of the mechanical properties of the glass: The volume removal rate increases approximately linearly with Young's modulus, and it decreases with fracture toughness and (approximately) the square of the Knoop hardness. The microroughness induced by lapping depends on the plastic and elastic properties of the glass, depending on abrasive shape. This is in contrast to deterministic microgrinding (fixed infeed rate), where it is determined from the plastic and fracture properties of the glass. We also show that Preston's coefficient has a similar dependence as lapping hardness on glass mechanical properties, as well as a linear dependence on abrasive size for the case of brittle material removal. These observations lead to the definition of an augmented Preston coefficient during brittle material removal. The augmented Preston coefficient does not depend on glass material properties or abrasive size and thus describes the interaction of the glass surface with the coolant-immersed abrasive grain and the backing plate. Numerical simulations of indentation are used to locate the origin of subsurface cracks and the distribution of residual surface and subsurface stresses, known to cause surface (radial) and subsurface (median, lateral) cracks.

  12. Vee-notch tool cuts specimens

    NASA Technical Reports Server (NTRS)

    Spier, R. A.

    1970-01-01

    Triangular cutting tool uses carbide tips for notching heat-treated or abrasive materials, and alloys subjected to high structural stresses. The tool is rigidly mounted in a slot of mating contour to prevent deflection during cutting of tensile specimens. No other expensive machine equipment is required.

  13. 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.

  14. The Development of Surface Profile Models in Abrasive Slurry Jet Micro-machining of Brittle and Ductile materials

    NASA Astrophysics Data System (ADS)

    Nouraei, Hooman

    In low-pressure abrasive slurry jet micro-machining (ASJM), a slurry jet of fine abrasive particles is used to erode micro-sized features such as holes and channels in a variety of brittle and ductile materials with a high degree of accuracy and repeatability without the need for a patterned mask. ASJM causes no tool wear and thermal damage, applies small forces on the workpiece, allows multilevel etching on a single substrate and is relatively quick and inexpensive. In this study for the first time, the mechanics of micro-slurry jet erosion and its relation to the fluid flow of the impinging jet was investigated using a newly developed ASJM system. Existing surface evolution models, previously developed for abrasive air jet machining (AJM), were evaluated and modified through the use of computational fluid dynamic (CFD) models for profile modeling of micro-channels and micro-holes machined with ASJM in brittle materials. A novel numerical-empirical model was also developed in order to compensate for the shortcoming of existing surface evolution models and provide a higher degree of accuracy in predicting the profiles of features in ductile materials machined with ASJM. In addition, the effect of process parameters on the minimum feature size attainable with ASJM as a maskless process was also examined and it was shown that the size of machined features could be further reduced.

  15. Performance Potential of Grinding Tools on Flexible Backing Produced of Grains with the Controlled Form

    NASA Astrophysics Data System (ADS)

    Shatko, D. B.; Lyukshin, V. S.; Bakumenko, V. N.

    2016-08-01

    The paper provides consideration to the approaches to designing new grinding tools on flexible backing - flap grinding wheels and grinding belts having abrasive grains with certain form and orientation in their structure. Methods to estimate the shape of abrasive grains have been analyzed. Experimental data has been presented how the form of a grain affects characteristics of tools on flexible backing. Recommendations on practical application of new tools have been given

  16. Proper bit design improves penetration rate in abrasive horizontal wells

    SciTech Connect

    Gentges, R.J. )

    1993-08-09

    Overall drilling penetration rates nearly tripled, and drill bit life nearly doubled compared to conventional bits when specially designed natural diamond and polycrystalline diamond compact (PDC) bits were used during a seven-well horizontal drilling program. The improvement in drilling performance from better-designed bits lowered drilling costs at ANR Pipeline Co.'s Reed City gas storage field in Michigan. Laboratory tests with scaled down bits used on abrasive cores helped determine the optimum design for drilling the gas storage wells. The laboratory test results and actual field data were used to develop a matrix-body natural diamond bit, which was later modified to become a matrix-body, blade-type polycrystalline diamond compact bit. This bit had excellent penetration rates and abrasion resistance. The paper describes the background to the project, bit selection, natural diamond bits, field results, new bit designs, and field results from the new design.

  17. 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.

  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. Abrasive blast material utilization in asphalt roadbed material

    SciTech Connect

    Means, J.L.; Nehring, K.W.; Heath, J.C.

    1996-12-31

    The State of California has promulgated rules on California-only hazardous wastes that offer the potential for some of these wastes to be recycled or reused. Abrasive blast material (ABM) from military and commercial operations such as sandblasting may fall into the category of waste that can be reused. Experiments were conducted on spent sandblasting grit to determine whether the grit could be incorporated into asphalt concrete for use as roadbed material, and a test roadbed was laid to evaluate the long-term stability of the metals found in the grit. Incorporation of the ABM in asphalt helps reduce the mobility of metal contaminants making the material suitable for reuse. The results of the initial characterization, treatability testing, and follow-up measurements of core samples taken from the test roadbed are presented to show that the use of abrasive blast material in asphalt roadbed material is a viable option under the proposed California regulatory standards.

  20. Abrasion resistance of muscovite in aeolian and subaqueous transport experiments

    NASA Astrophysics Data System (ADS)

    Anderson, Calvin J.; Struble, Alexander; Whitmore, John H.

    2017-02-01

    Complementary aeolian and subaqueous transport experiments showed a trend in muscovite abrasion that may be useful for identifying ancient sandstones as aeolian or subaqueous in origin. We found that our experimental aeolian processes pulverized the micas quickly, while our subaqueous processes did not. In a pair of abrasion resistance experiments conducted with micaceous quartz sand, it was found that large muscovite grains were (1) reduced by aeolian processes to less than 500 μm in just 4 days, and (2) preserved by subaqueous processes to 610 ± 90 μm even after 356 days. At 20 days of aeolian transport no loose micas could be found even under the microscope, but after a year of subaqueous transport loose muscovite grains could still be seen with the naked eye. Thus, the occurrence and character of micas in a sandstone, particularly muscovite, may be helpful in determining the ancient depositional process.

  1. 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.

  2. 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

  3. 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.

  4. Dental abrasion as a cutting process.

    PubMed

    Lucas, Peter W; Wagner, Mark; Al-Fadhalah, Khaled; Almusallam, Abdulwahab S; Michael, Shaji; Thai, Lidia A; Strait, David S; Swain, Michael V; van Casteren, Adam; Renno, Waleed M; Shekeban, Ali; Philip, Swapna M; Saji, Sreeja; Atkins, Anthony G

    2016-06-06

    A mammalian tooth is abraded when a sliding contact between a particle and the tooth surface leads to an immediate loss of tooth tissue. Over time, these contacts can lead to wear serious enough to impair the oral processing of food. Both anatomical and physiological mechanisms have evolved in mammals to try to prevent wear, indicating its evolutionary importance, but it is still an established survival threat. Here we consider that many wear marks result from a cutting action whereby the contacting tip(s) of such wear particles acts akin to a tool tip. Recent theoretical developments show that it is possible to estimate the toughness of abraded materials via cutting tests. Here, we report experiments intended to establish the wear resistance of enamel in terms of its toughness and how friction varies. Imaging via atomic force microscopy (AFM) was used to assess the damage involved. Damage ranged from pure plastic deformation to fracture with and without lateral microcracks. Grooves cut with a Berkovich diamond were the most consistent, suggesting that the toughness of enamel in cutting is 244 J m(-2), which is very high. Friction was higher in the presence of a polyphenolic compound, indicating that this could increase wear potential.

  5. Development of underwater cutting system by abrasive water-jet

    NASA Astrophysics Data System (ADS)

    Demura, Kenji; Yamaguchi, Hitoshi

    1993-09-01

    The technology to cut objects in the ocean's depths with abrasive water jets was examined for possible application in view of the greater water depths and sophistication involved in work on the ocean floor today. A test model was developed to study this technology's safety and practicability. The test model was designed for use at great water depths and has functions and a configuration that are unlike equipment used on land. A continuous, stable supply of abrasive is a distinctive design feature. In land applications, there had been problems with plugged tubes and an uneven supply. For this reason, the abrasive was converted to slurry form, and a continuous pressurized tube pump system was adopted for supply to the nozzle head. Also, a hydraulic motor that does not employ oil or electric power was used to provide an underwater drive that is environment-friendly. The report outlines the technology's general design concept including its distinctive functions and its configuration for use at great depths, and the report provides great detail on the equipment.

  6. Correlation Between Particle Velocities and Conditions of Abrasive Waterjet Formation

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Long

    1990-01-01

    The velocities of water and abrasive particles in abrasive waterjet(AWJ) were measured by the use of Laser Transit Anemometer(LTA). A setup for the velocity measurement was constructed and a statistical technique was used to improve the accuracy of the velocity determination. A comparison of the magnitude of velocities determined by LTA, Piezoelectric Force Transducer and Schlieren Photograph clearly indicates the feasibility of the use of LTA. The velocities of water and particles were measured for different diameters of water and slurry nozzles, abrasive mass flow rates and particle sizes. The performed experiments enabled us to evaluate the effects of conditions of jet formation on the particles velocities. An empirical equation for the prediction of particles velocities was constructed by the use of obtained results. The coefficient of correlation between experimental and computed results is equal to 0.93. The acquired information can be used to select the operational parameters in AWJ cutting. The obtained results also provide information on the acceleration mechanism of entrained particles, which may be used to improve the design of slurry nozzle.

  7. Characterization of Effective Parameters in Abrasive Waterjet Rock Cutting

    NASA Astrophysics Data System (ADS)

    Oh, Tae-Min; Cho, Gye-Chun

    2014-03-01

    The rock cutting performance of an abrasive waterjet is affected by various parameters. In this study, rock cutting tests are conducted with different energy (i.e., water pressure, traverse speed, and abrasive feed rate), geometry (i.e., standoff distance), and material parameters [i.e., uniaxial compressive strength (UCS)]. In particular, experimental tests are carried out at a long standoff distance (up to 60 cm) to consider field application. The effective parameters of the rock cutting process are identified based on the relationships between the cutting performance indices (depth, width, and volume) and parameters. In addition, the cutting efficiency is analyzed with effective parameters as well as different pump types and the number of cutting passes considering the concept of kinetic jet energy. Efficiency analysis reveals that the cutting depth efficiency tends to increase with an increase in the water pressure and traverse speed and with a decrease in the standoff distance and UCS. Cutting volume efficiency strongly depends on standoff distance. High efficiency of cutting volume is obtained at a long standoff distance regardless of the pump type. The efficiency analysis provides a realistic way to optimize parameters for abrasive waterjet rock excavation.

  8. 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.

  9. Characterization of the resistance of pyrolytic carbon to abrasive wear.

    PubMed

    Vitale, E; Giusti, P

    1995-12-01

    Si-alloyed pyrolitic carbon (PyC) is currently employed in many biomedical devices, due to its fairly good biological compatibility and non biodegradeability. For prosthetic heart valve applications, required to operate safely for many years, the resistance to abrasive wear is one of the limiting factors which must be accurately evaluated. The present study reports on abrasive wear testing of Ti/PyC and PyC/PyC sliding couples. For both couples it was found that the wear behaviour can be shifted from a low wear regime, characterised by very small wear rates and reduced scatter, to a high wear regime, characterised by high wear rates and high scatter, due to the presence of particle contamination coming from the environment and/or from the specimen polishing process. Actual biomedical devices, particularly heart valves, should not experience the high wear regime, due to the absence of any hard particle contamination source. The wear observed in these items is in fact minimal and may depend on mechanisms other than abrasive wear. In these conditions the experimental evaluation of the wear behaviour should definetely be performed by tests on actual devices.

  10. Surface characterization of current composites after toothbrush abrasion.

    PubMed

    Takahashi, Rena; Jin, Jian; Nikaido, Toru; Tagami, Junji; Hickel, Reinhard; Kunzelmann, Karl-Heinz

    2013-01-01

    The present study was designed to evaluate the surface roughness and the gloss of current composites before and after toothbrush abrasion. We assessed forty dimensionally standardized composite specimens (n=8/group) from five composites: two nanohybrids (i. e., IPS Empress Direct Enamel and IPS Empress Direct Dentin), two microhybrids (i. e., Clearfil AP-X and Filtek Z250) and one organically modified ceramics (Admira). All of the specimens were polished with 4000-grid silicon carbide papers. Surface roughness was measured with a profilometer and gloss was measured with a glossmeter before and after powered toothbrush abrasion with a 1:1 slurry (dentifrice/tap water) at 12,000 strokes in a toothbrush simulator. There was a significant increase in the surface roughness and a reduction in gloss after toothbrush abrasion in all of the composites except Clearfil AP-X (p<0.05). Simple regression analysis showed that there was not an association between the surface roughness and the gloss (R(2)=0.191, p<0.001).

  11. Abrasive water jet cutting as a new procedure for cutting cancellous bone--in vitro testing in comparison with the oscillating saw.

    PubMed

    Schwieger, Karsten; Carrero, Volker; Rentzsch, Reemt; Becker, Axel; Bishop, Nick; Hille, Ekkehard; Louis, Hartmut; Morlock, Michael; Honl, Matthias

    2004-11-15

    The quality of bone cuts is assessed by the accuracy and biological potency of the cut surfaces. Conventional tools (such as saws and milling machines) can cause thermal damage to bone tissue. Water jet cutting is nonthermal; that is, it does not generate heat. This study investigates whether the abrasive jet cutting quality in cancellous bone with a biocompatible abrasive is sufficient for the implantation of endoprostheses or for osteotomies. Sixty porcine femoral condyles were cut with an abrasive water jet and with an oscillating saw. alpha-lactose-monohydrate was used as a biocompatible abrasive. Water pressure (pW = 35 and 70 MPa) and abrasive feed rate (m = 0.5, 1, and 2 g/s) were varied. As a measure of the quality of the cut surface the cutting gap angle (delta) and the surface roughness (Ra) were determined. The surface roughness was lowest for an abrasive feed rate of m = 2 g/s (jet direction: 39 +/- 16 microm, advance direction: 54 +/- 22 microm). However, this was still significantly higher than the surface roughness for the saw group (jet direction: 28 +/- 12 microm, advance direction: 36 +/- 19 microm) (p < 0.001 for both directions). At both pressure levels the greatest cutting gap angle was observed for a mass flow rate of m = 1 g/s (pW = 35 MPa: delta = 2.40 +/- 4.67 degrees ; pW = 70 MPa: delta = 4.13 +/- 4.65 degrees), which was greater than for m = 0.5 g/s (pW = 35 MPa: delta = 1.63 +/- 3.89 degrees ; pW = 70 MPa: delta = 0.36 +/- 1.70 degrees) and m = 2 g/s (pW =70 MPa: delta = 0.06 +/- 2.40 degrees). Abrasive water jets are suitable for cutting cancellous bone. The large variation of the cutting gap angle is, however, unfavorable, as the jet direction cannot be adjusted by a predefined value. If it is possible to improve the cutting quality by a further parameter optimization, the abrasive water jet may be the cutting technique of the future for robotic usage.

  12. 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.

  13. 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

  14. Microstructural effects in abrasive wear: Final report for period September 15, 1981--March 14, 1986

    SciTech Connect

    Kosel, T.H.

    1988-03-08

    This report summarizes research performed on abrasion of metallic alloys. The work was designed to improve our understanding of the factors affecting abrasion rates in two-phase alloys containing large, hard second-phase particles (SPPs) such as carbides, since this class of alloys generally has very high abrasion resistance owing to the presence of such carbides. The project was divided into sections dealing with material removal in the carbide and matrix phases. The materials studied included Stellite and high Cr-Mo white cast irons and a set of specially prepared model alloys containing one of six types of artificial SPPs dispersed in a sintered matrix of pure Cu. Scratch tests were employed to simulate abrasion mechanisms, and specially designed scratch test systems were fabricated to permit scratch testing in-situ in the scanning electron microscope (SEM) and to permit scratches to be made at fixed depths of cut rather than fixed loads. Three types of abrasion tests were employed; a dry-sand rubber wheel abrasion test; a low-speed ''gouging'' abrasion test employing a special low-speed Al/sub 2/O/sub 3/ grinding wheel; and a pin-on-disc abrasion test using abrasive paper. Abrasive type and size was varied in the rubber wheel and the pin-on-disc tests. 27 refs., 10 figs., 5 tabs.

  15. 2,2'-Azobis (2-Amidinopropane) Dihydrochloride Is a Useful Tool to Impair Lung Function in Rats.

    PubMed

    Moreira Gomes, Maria D; Carvalho, Giovanna M C; Casquilho, Natalia V; Araújo, Andressa C P; Valença, Samuel S; Leal-Cardoso, Jose H; Zin, Walter A

    2016-01-01

    Recently, several studies have reported that respiratory disease may be associated with an increased production of free radicals. In this context, 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) is a free radical-generating compound widely used to mimic the oxidative stress state. We aimed to investigate whether AAPH can generate lung functional, inflammatory, histological and biochemical impairments in the lung. Wistar rats were divided into five groups and instilled with saline solution (714 μL/kg, CTRL group) or different amounts of AAPH (25, 50, 100, and 200 mg/kg, 714 μL/kg, AAPH groups). Seventy-two hours later the animals were anesthetized, paralyzed, intubated and static elastance (Est), viscoelastic component of elastance (ΔE), resistive (ΔP1) and viscoelastic (ΔP2) pressures were measured. Oxidative damage, inflammatory markers and lung morphometry were analyzed. ΔP1 and Est were significantly higher in AAPH100 and AAPH200 than in the other groups. The bronchoconstriction indexes were larger in AAPH groups than in CTRL. The area occupied by collagen and elastic fibers, polymorpho- and mononuclear cells, malondialdehyde and carbonyl groups levels were significantly higher in AAPH200 than in CTRL. In comparison to CTRL, AAPH200 showed significant decrease and increase in the activities of superoxide dismutase and catalase, respectively. AAPH augmented the release of pro-inflammatory cytokines IL-1β, IL-6 e TNF-α. Hence, exposure to AAPH caused significant inflammatory alterations and redox imbalance accompanied by altered lung mechanics and histology. Furthermore, we disclosed that exposure to AAPH may represent a useful in vivo tool to trigger lung lesions.

  16. 2,2′-Azobis (2-Amidinopropane) Dihydrochloride Is a Useful Tool to Impair Lung Function in Rats

    PubMed Central

    Moreira Gomes, Maria D.; Carvalho, Giovanna M. C.; Casquilho, Natalia V.; Araújo, Andressa C. P.; Valença, Samuel S.; Leal-Cardoso, Jose H.; Zin, Walter A.

    2016-01-01

    Recently, several studies have reported that respiratory disease may be associated with an increased production of free radicals. In this context, 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) is a free radical-generating compound widely used to mimic the oxidative stress state. We aimed to investigate whether AAPH can generate lung functional, inflammatory, histological and biochemical impairments in the lung. Wistar rats were divided into five groups and instilled with saline solution (714 μL/kg, CTRL group) or different amounts of AAPH (25, 50, 100, and 200 mg/kg, 714 μL/kg, AAPH groups). Seventy-two hours later the animals were anesthetized, paralyzed, intubated and static elastance (Est), viscoelastic component of elastance (ΔE), resistive (ΔP1) and viscoelastic (ΔP2) pressures were measured. Oxidative damage, inflammatory markers and lung morphometry were analyzed. ΔP1 and Est were significantly higher in AAPH100 and AAPH200 than in the other groups. The bronchoconstriction indexes were larger in AAPH groups than in CTRL. The area occupied by collagen and elastic fibers, polymorpho- and mononuclear cells, malondialdehyde and carbonyl groups levels were significantly higher in AAPH200 than in CTRL. In comparison to CTRL, AAPH200 showed significant decrease and increase in the activities of superoxide dismutase and catalase, respectively. AAPH augmented the release of pro-inflammatory cytokines IL-1β, IL-6 e TNF-α. Hence, exposure to AAPH caused significant inflammatory alterations and redox imbalance accompanied by altered lung mechanics and histology. Furthermore, we disclosed that exposure to AAPH may represent a useful in vivo tool to trigger lung lesions. PMID:27812337

  17. 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

  18. 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

  19. Mechanical issues in laser and abrasive water jet cutting

    NASA Astrophysics Data System (ADS)

    Singh, Jogender; Jain, Sulekh C.

    1995-01-01

    In forging and other metal-working industries, lasers and abrasive water jets are being applied to cut a variety of metal products to improve productivity and reduce costs. As described in the following, both the processes have their unique cutting capabilities and characteristics. Before selecting one, however, users must be aware of how each technique influences the end product as well as its performance (e.g., high-cycle fatigue life). For this article, we examined the mechanics of these two cutting processes by studying their effects on Ti-6Al-4Vand A286 steel.

  20. Mechanical issues in laser and abrasive water jet cutting

    NASA Astrophysics Data System (ADS)

    Singh, Jogender; Jain, Sulekh C.

    1995-01-01

    In forging and other metal-working industries, lasers and abrasive water jets are being applied to cut a variety of metal products to improve productivity and reduce costs. As described, both the processes have their unique cutting capabilities and characteristics. Before selecting one, however, users must be aware of how each technique influences the end product as well as its performance (e.g., high-cycle fatigue life). For this article, we examined the mechanics of these two cutting processes by studying their effects on Ti-6Al-4V and A286 steel.

  1. 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.

  2. Solution of the Roth-Marques-Durian rotational abrasion model

    NASA Astrophysics Data System (ADS)

    Chen, Bryan Gin-Ge

    2011-03-01

    We solve the rotational abrasion model of Roth, Marques, and Durian [Phys. Rev. EPRLTAO1539-375510.1103/PhysRevE.83.031303 83, 031303 (2011)], a one-dimensional quasilinear partial differential equation resembling the inviscid Burgers equation with the unusual feature of a step function factor as a coefficient. The complexity of the solution is primarily in keeping track of the cases in the piecewise function that results from certain amputation and interpolation processes, so we also extract from it a model of an evolving planar tree graph that tracks the evolution of the coarse features of the contour.

  3. Diffuse corneal abrasion after ocular exposure to laundry detergent pod.

    PubMed

    Whitney, Rachel E; Baum, Carl R; Aronson, Paul L

    2015-02-01

    Although ocular injury from alkaline household cleaning products is well described, there is less known about the significance and extent of injury with ocular exposure to detergent pods. We report a 12-month-old with diffuse corneal abrasion caused by ocular contact with a laundry detergent pod. In addition to the known risks with aspiration with detergent pods, the potential for severe ocular injury is important for parents and clinicians to recognize. Children with ocular exposure to detergent pods should seek immediate medical care.

  4. The "plantar test" apparatus (Ugo Basile Biological Apparatus), a controlled infrared noxious radiant heat stimulus for precise withdrawal latency measurement in the rat, as a tool for humans?

    PubMed

    Montagne-Clavel, J; Oliveras, J L

    1996-01-01

    In the present study, we precisely and automatically measured the withdrawal latency to noxious radiant heat application in unrestrained male rats and in human subjects of both sexes, by means of the "plantar test" apparatus (Ugo Basile Biological Apparatus). The infrared light stimulus of this tool was applied underneath the hindpaws of rats and the middle fingers of human subjects. With one right and one left stimulation every 10 min, we observed a decrease in latency over a 40-min testing period in rats; the latency reached a mean value of 5.08 +/- 0.25 sec after 40 min with a 36-W stimulus, which corresponded to 46.5 degrees C. In pilot experiments, also performed on rats, we showed that the opiate morphine (10 mg/kg, i.p.) produced remarkable increases of the withdrawal latency only in "naive" animals (i.e., ones that had never experienced the plantar test stimulus) and not in animals "habituated" to it. Among humans, we noted gender differences, such as less sensitivity to the infrared noxious radiant heat for women, particularly during the menstrual period. A difference from rats was that there was no significant latency modification along the 40-min testing period for either women or men, with a mean latency of 5.61 +/- 0.18 sec (47.5 degrees C) for the women and 4.39 +/- 0.10 sec (45.5 degrees C) for the men. These data confirm the reliability of the plantar test in rats, and demonstrate the possible use of an infrared source in human subjects as a noxious heat stimulus; the withdrawal reaction to this stimulus is emphasized as a good index of nociception in humans.

  5. Evidence for Martian electrostatic charging and abrasive wheel wear from the Wheel Abrasion Experiment on the Pathfinder Sojourner rover

    NASA Astrophysics Data System (ADS)

    Ferguson, Dale C.; Kolecki, Joseph C.; Siebert, Mark W.; Wilt, David M.; Matijevic, Jacob R.

    1999-04-01

    The Wheel Abrasion Experiment (WAE) on the Mars Pathfinder rover was designed to find out how abrasive the Martian dust would be on strips of pure metals attached to one of the wheels. A specially modified wheel, with 15 thin film samples (five each of three different metals), specularly reflected sunlight to a photovoltaic sensor. When the wheel was rotated to present the different sample surfaces to the sensor, the resulting signal was interpreted in terms of dust adhesion and abrasive wear. Many data sequences were obtained. Ground tests of similar wheels in a simulated Martian environment showed that static charging levels of 100-300 V could be expected. To prevent the possibility of Paschen discharge in the low-pressure Martian atmosphere, charge dissipation points were added to the Sojourner rover and were shown in ground tests to keep charging levels at 80 V or less. Nevertheless, significant dust accumulations on Sojourner's wheels may be interpreted as evidence for electrostatic charging. Simple considerations of the expected maximum level of charging and electrostatic dust adhesion lead to an estimate for the size of the adhering dust grains. From the WAE data, it is hypothesized that the photoelectric effect is the most important mechanism for slow discharge in Martian daylight. Sensor signals obtained late in the Pathfinder mission show that significant wheel wear was seen on the metal wheel strips, with the most wear on the thinnest aluminum samples and the least on the thickest nickel and platinum samples. An estimate is made of the reflectance of the adhering Martian dust. The depth of dig of the WAE wheel shows that the dust is in some places very loose and in others tightly packed. Finally, comparison of the WAE results with ground test results makes possible a comparison of the Martian soil with mineral grain types and sizes found on Earth and show that the Martian dust is fine-grained and of limited hardness.

  6. The serum D-xylose test as a useful tool to identify malabsorption in rats with antigen specific gut inflammatory reaction

    PubMed Central

    Antunes, Danielle Mota Fontes; da Costa, Janilda Pacheco; Campos, Sylvia Maria Nicolau; Paschoal, Patrícia Olaya; Garrido, Valéria; Siqueira, Munique; Teixeira, Gerlinde Agate Platais Brasil; Cardoso, Gilberto Perez

    2009-01-01

    The inappropriate immune response to foods, such as peanut, wheat and milk may be the basis in the pathogenesis of enteropathies like coeliac and Crohn disease, which present small intestinal malabsorption. A number of recent studies have utilized d-xylose absorption as an investigative tool to study small intestinal function in a variety of clinical settings. Thus, the aim of this experimental study was to evaluate the intestinal absorption of d-xylose in an antigen-specific gut inflammatory reaction rat model. Animals of the experimental group were inoculated with peanut protein extract before their exposure to a challenge diet containing exclusively peanut seeds to induce the gut inflammatory reaction caused by peanut allergy. Our results show that systemic inoculation with peanut protein extract renders significantly higher antibody titres (5.085 ± 0.126 units) (P < 0.0001) than control rats (0.905 ± 0.053 units) and that the antibody titres correlate positively to an inflammatory alteration of the gut morphology (P < 0.0001). Animals pertaining to the experimental group showed an intestinal absorption of d-xylose lower than control rats (P < 0.0001). We also observed that d-xylose absorption correlates negatively with IgG titres and positively with morphometric parameters (Pearson correlation). In conclusion, the use of serum d-xylose test was useful to identify the presence of small intestinal malabsorption in our antigen specific gut inflammatory reaction rat model. PMID:19335552

  7. Cutting meat with bone using an ultrahigh pressure abrasive waterjet.

    PubMed

    Wang, J; Shanmugam, D K

    2009-04-01

    An experimental study of abrasive waterjet (AWJ) cutting of beef, pork and lamb meat with and without bone is presented. Salt particles were used as the abrasives. It has been found that an AWJ could significantly increase the depth of cut with much improved cut quality in cutting pure meat as compared to plain (or pure) waterjet cutting, while a plain waterjet was incapable of cutting bone satisfactorily. The study shows that AWJ cutting produced a very narrow kerf of less than 1mm and hence resulted in mush less meat loss than the traditional cutting processes, and meat can be cut at room temperature to eliminate the freezing or chilling costs. It is shown that a traverses speed of 20mm/s can be used to cut through 44mm thick beef rib bones with good cut quality. When slicing pure meat of 150mm thickness, the traverse speed of 66.67mm/s can yield very good cut quality. It is suggested that AWJ cutting is a viable technology for meat cutting. Plausible trends for the depth of cut, cutting rate and cut quality with respect to the process variables are discussed. Recommendations are finally made for the selection of the most appropriate process parameters for cutting meat of a given thickness.

  8. 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.

  9. 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.

  10. 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.

  11. Abrasive-assisted Nickel Electroforming Process with Moving Cathode

    NASA Astrophysics Data System (ADS)

    REN, Jianhua; ZHU, Zengwei; XIA, Chunqiu; QU, Ningsong; ZHU, Di

    2017-03-01

    In traditional electroforming process for revolving parts with complex profiles, the drawbacks on surface of deposits, such as pinholes and nodules, will lead to varying physical and mechanical properties on different parts of electroformed components. To solve the problem, compositely moving cathode is employed in abrasive-assisted electroforming of revolving parts with complicated profiles. The cathode translates and rotates simultaneously to achieve uniform friction effect on deposits without drawbacks. The influences of current density and translation speed on the microstructure and properties of the electroformed nickel layers are investigated. It is found that abrasive-assisted electroforming with compound cathode motion can effectively remove the pinholes and nodules, positively affect the crystal nucleation, and refine the grains of layer. The increase of current density will lead to coarse microstructure and lower micro hardness, from 325 HV down to 189 HV. While, faster translational linear speed produces better surface quality and higher micro hardness, from 236 HV up to 283 HV. The weld-ability of the electroformed layers are also studied through the metallurgical analysis of welded joints between nickel layer and 304 stainless steel. The electrodeposited nickel layer shows fine performance in welding. The novel compound motion of cathode promotes the mechanical properties and refines the microstructure of deposited layer.

  12. 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.

  13. 'RAT' Hole on 'Pilbara' (pre-RAT)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The Mars Exploration Rover Opportunity broke its own record for the deepest hole ground into a rock on another planet with a 7.2-millimeter (about 0.28-inch) grind on the rock 'Pilbara,' on the rover's 86th sol on Mars.

    This image is from the rover's panoramic camera and features Pilbara before the rover ground into it with its rock abrasion tool. After careful examination of the rock, the rock abrasion tool engineers determined that the upper left portion (visible in this image) of Pilbara was the safest area to grind. The now familiar 'blueberries,' or spherules, are present in this rock, however, they do not appear in the same manner as other berries examined during this mission. Reminiscent of a golf tee, the blueberries sit atop a 'stem,' thus making them even more of an obstacle through which to grind. The left side of the rock is relatively berry-free and proved to be an ideal spot for the procedure.

    The team has developed a new approach to commanding the rock abrasion tool that allows for more aggressive grinding parameters. The tool is now programmed, in the event of a stall, to retreat from its target and attempt to grind again. This allows the grinder to essentially reset itself instead of aborting its sequence altogether and waiting for further commands from rover planners.

  14. Millwright Apprenticeship. Related Training Modules. 4.1-4.6 Tools.

    ERIC Educational Resources Information Center

    Lane Community Coll., Eugene, OR.

    This packet, part of the instructional materials for the Oregon apprenticeship program for millwright training, contains six modules covering tools. The modules provide information on the following topics: boring and drilling tools; cutting tools, files and abrasives; holding and fastening tools; fastening devices; basic science--simple mechanics;…

  15. Process monitoring evaluation and implementation for the wood abrasive machining process.

    PubMed

    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.

  16. Solidification/stabilization of spent abrasives and use as nonstructural concrete

    SciTech Connect

    Brabrand, D.J.; Loehr, R.C. )

    1993-01-01

    Tons of spent abrasives result each year from the removal of old paint from bridges. Because the spent abrasives contain metals from the paint, some spent abrasives may be considered hazardous by the Toxicity Characteristic (TC) criteria. Incorporation of the spent blasting abrasives in nonstructural concrete (rip-rap, dolphins) offers an opportunity to recycle the spent abrasives while immobilizing potentially leachable metals. This study focused on the Portland Cement Solidification/Stabilization (S/S) of spent blasting abrasives taken from a bridge located in Southeast Texas. The study examined (a) the cadmium, chromium, and lead concentrations in extracts obtained by using the Toxicity Characteristic Leaching Procedure (TCLP) and (b) the compressive strengths of Portland Cement mixes that contained different amounts of the spent abrasives. Performance was measured by meeting the TC criteria as well as the requirements for compressive strength. Study results indicated that considerable quantities of these spent abrasives can be solidified/stabilized while reducing the leachability of cadmium, chromium, and lead and producing compressive strengths over 6,895 kN/m[sup 2] (1,000 psi).

  17. Monitoring of the Abrasion Processes (by the Example of Alakol Lake, Republic of Kazakhstan)

    ERIC Educational Resources Information Center

    Abitbayeva, Ainagul; Valeyev, Adilet; Yegemberdiyeva, Kamshat; Assylbekova, Aizhan; Ryskeldieva, Aizhan

    2016-01-01

    The purpose of the study is to analyze the abrasion processes in the regions of dynamically changing Alakol lake shores. Using the field method, methods of positioning by the GPS receiver and interpretation of remote sensing data, the authors determined that abrasion processes actively contributed to the formation the modern landscape, causing the…

  18. 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.

  19. Abrasivity of toothpastes. An in vitro study of toothpastes marketed in Norway.

    PubMed

    Svinnseth, P N; Gjerdet, N R; Lie, T

    1987-06-01

    The purpose of this study was to measure the abrasivity of 23 toothpastes available on the Norwegian market. Additionally, the pH was registered. The testing was based on The British Standards Institution's specification for toothpastes, using a profilometer technique to evaluate the abrasion. The results showed that the abrasivity ranged from 0.049 to 1.367 relative to a standard reference paste. The products were classified as having 'none/slight', 'medium', or 'high' abrasivity. The pH varied between 3.7 and 10.1. Products with low pH showed evidence of a combined erosive/abrasive effect. For some brands there were statistically significant differences between the fluoride and the nonfluoride version.

  20. 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.

  1. 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.

  2. Thickness-Independent Ultrasonic Imaging Applied to Abrasive Cut-Off Wheels: An Advanced Aerospace Materials Characterization Method for the Abrasives Industry. A NASA Lewis Research Center Technology Transfer Case History

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Farmer, Donald A.

    1998-01-01

    Abrasive cut-off wheels are at times unintentionally manufactured with nonuniformity that is difficult to identify and sufficiently characterize without time-consuming, destructive examination. One particular nonuniformity is a density variation condition occurring around the wheel circumference or along the radius, or both. This density variation, depending on its severity, can cause wheel warpage and wheel vibration resulting in unacceptable performance and perhaps premature failure of the wheel. Conventional nondestructive evaluation methods such as ultrasonic c-scan imaging and film radiography are inaccurate in their attempts at characterizing the density variation because a superimposing thickness variation exists as well in the wheel. In this article, the single transducer thickness-independent ultrasonic imaging method, developed specifically to allow more accurate characterization of aerospace components, is shown to precisely characterize the extent of the density variation in a cut-off wheel having a superimposing thickness variation. The method thereby has potential as an effective quality control tool in the abrasives industry for the wheel manufacturer.

  3. 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.

  4. Video-Tracking-Box linked to Smart software as a tool for evaluation of locomotor activity and orientation in brain-injured rats.

    PubMed

    Otero, Laura; Zurita, Mercedes; Aguayo, Concepción; Bonilla, Celia; Rodríguez, Alicia; Vaquero, Jesús

    2010-04-30

    Injuries of the Central Nervous System (CNS) cause devastating and irreversible losses of function. In order to analyze the deficits subsequent to brain injury it is necessary to use behavioral tests which evaluate cerebral dysfunction. In this study, we describe a new tool, the Video-Tracking-Box (VTB) linked to Smart software. This new method adequately quantifies parameters related to locomotor activity and orientation in brain-injured rats. This method has been used in our laboratory in order to measure behavioral outcome after brain injury caused by intracerebral hemorrhage (ICH) in adult Wistar rats. In our experimental model, ICH was induced by stereotactic injection of 0.5U of collagenase type IV in striatum. ICH injured rats decreased its motor coordination and presented deficits in cognitive memory. VTB-Smart test was sensitive to chronic locomotor and orientation dysfunction, and it was performed between 1 and 5 months after ICH. Our results revealed a significant increase in motor latency and loss of spatial orientation in the damaged-animals compared with intact animals. The data demonstrate that our VTB, joined to Smart software, offers a reliable measure to assess motor dysfunction and orientation after brain injury.

  5. In vitro and ex vivo binding to uterine progestin receptors of the rat as a tool to assay progestational activity of glucocorticoids.

    PubMed

    Luzzani, F; Gallico, L; Glässer, A

    1982-01-01

    The competition of some widely employed glucocorticoids with the binding of [3H]-promegestone, a highly potent synthetic progestagen, to uterine cytosol progestin receptors of the immature rat has been studied both in in vitro and ex vivo experiments. The relative binding affinities (RBA's) to progesterone were determined in vitro: fluocinolone acetonide greater than triamcinolone acetonide greater than betamethasone 17-valerate greater than prednisolone, betamethasone, triamcinolone and cortisol. After pretreating rats in vivo with progesterone or chlormadinone acetate (subcutaneously), a dose-dependent decrease in in vitro binding of [3H]-promegestone to uterine cytosol was evident. Similar decreases were obtained after pretreatment with some of the other glucocorticoids tested. Potency ratios to progesterone, arbitrarily set at 1.0, were: fluocinolone acetonide 86.7, triamcinolone acetonide 5.6, betamethasone valerate 4.1, chlormadinone acetate 2.6. Prednisolone, betamethasone, triamcinolone and cortisol were inactive. Both the in vitro and the ex vivo results clearly indicate that glucocorticoids interact with the uterine cytosol progestin receptor system, depending on their chemical structures; this interaction may account for some of their unwanted side-effects in the endocrine system. Moreover, this experimental system may prove to be a useful tool for evaluation of the progestational activities of glucocorticoids and other steroids, using the rat as an animal model.

  6. An Investigation of Abrasive Wear Behaviour of Al 2014-SiC Composites

    NASA Astrophysics Data System (ADS)

    Çalin, Recep; Cilasun, Niyazi Selçuk

    2015-04-01

    In this study, the effects of SiC reinforcement volume fractions on hardness, porosity and abrasive wear behaviour were examined in Al 2014-SiC (<92.3 μm) reinforced metal matrix composites (MMCs) of 3%, 6% and 12% reinforcement-volume (R-V) ratios produced by melt-stirring. Abrasive wear tests were carried out by 320 mesh Al2O3 abrasive paper and a pin-on-disc wear test apparatus, under 10N, 20N and 30N load, and at 0.2 ms-1 sliding speed. The same specimens were tested by 150, 240 and 320 mesh abrasive paper at 0.2 ms-1 sliding speed, under 10N, 20N and 30N load. After the tests, the microstructures of the worn surfaces were examined with scanning electron microscope (SEM) studies and EDS analyses. Besides, the amount of hardness and porosity of the specimens were identified. It was recorded that the amounts of hardness and porosity increases as the SiC reinforcement in the composite increases. The highest amount of abrasive wear was recorded in the specimens with 3% reinforcements. It was identified that the amount of abrasive wear decreases while the SiC reinforcement in the composite structure increases by volume, and that the amount of porosity and reinforcement volume (R-V) ratio are important parameters in abrasive wear.

  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. 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.

  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. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. Study on planarization machining of sapphire wafer with soft-hard mixed abrasive through mechanical chemical polishing

    NASA Astrophysics Data System (ADS)

    Xu, Yongchao; Lu, Jing; Xu, Xipeng

    2016-12-01

    This study investigated the material removal mechanism of sapphire wafer with soft-hard mixed abrasives through mechanical chemical polishing (MCP). The polishing film, which contains diamond as hard abrasives and high reactivity silica as soft abrasives, is prepared through sol-gel technology. Silica abrasives with regular spherical shape and high reactivity are prepared through hydrolysis-precipitation. Diamond grits with three different particle sizes are used as abrasives. Results show that the rate of material removal of mixed abrasives during MCP is more than 52.6% of that of single hard abrasives and the decrease in surface roughness is more than 21.6% of that of single hard abrasives. These results demonstrate that the ideal planarization of sapphire wafer with high removal rate and good surface quality can be achieved when the effect of mechanical removal of hard abrasives and the chemical corrosion effect of soft abrasives are in dynamic equilibrium. A model that describes the material removal mechanism of sapphire with mixed abrasives during MCP is proposed. The results of thermodynamic calculation and polishing residue analysis are used to demonstrate the rationality of the model.

  16. 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

  17. You Dirty Rat!

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image taken by the Mars Exploration Rover Opportunity's panoramic camera shows the rover's rock abrasion tool before and after it ground into a rock at Meridiani Planum, Mars. The red dust coating on the instrument is thought to be a form of the mineral hematite. The image on the left was taken on the 29th martian day, or sol, of the rover's mission, and the image on the right on the 31st sol.

  18. Studies on polishing of Ti and Ag-Pd-Cu-Au alloy with five dental abrasives.

    PubMed

    Hirata, T; Nakamura, T; Takashima, F; Maruyama, T; Taira, M; Takahashi, J

    2001-08-01

    Titanium (Ti) and Ag-Pd-Cu-Au alloy were examined for their polishing behaviour by conducting manually controlled polishing tests using five dental abrasives [carborundum point (CR) and silicone points (R1 and R2)] driven by a high torque micromotor with rotational speeds ranging from 2000 to 15 000 r.p.m. Polishing of Ti resulted in less volume of removal upon polishing, a rougher surface and larger loss of abrasives, compared with polishing of Ag-Pd-Cu-Au alloy. Polishing of Ti with a rotational speed of 15 000 r.p.m. led to the largest volume of removal upon polishing, whilst that of 10 000 r.p.m. produced the optimal volume for Ag-Pd-Cu-Au alloy. It was concluded that Ti was much more difficult to polish, requiring special care (e.g. frequent exchange of abrasives). Development of new abrasives for polishing Ti is required.

  19. 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.

  20. 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.

  1. Hardness and Abrasion Resistance of Nanocrystalline Nickel Alloys Near the Hall-Petch Breakdown Regime

    DTIC Science & Technology

    2003-01-01

    for structural applications. In this work we discuss the hardness and scratch resistance of nanocrystalline nickel and nickel-tungsten solid solution alloys...hardness and abrasion data. The role of solid solution alloying on this breakdown is also discussed.

  2. The effect on cast post dimensions of casting investment and airborne particle abrasion.

    PubMed

    Hashem, Danya; German, Matthew J; Wassell, Robert W

    2011-09-01

    Cast posts can sometimes prove difficult to seat fully during fitting. This study compared two different liquid/water dilutions for phosphate bonded investment and the effect of controlled airborne particle abrasion on resulting post diameter. After measuring polymeric post patterns (n = 18), 3 groups were invested using concentrated solution and 3 groups using dilute solution. After casting they were weighed and remeasured then exposed to airborne particle abrasion. Both solutions produced oversized cast posts. Mean diameter reduction during airborne particle abrasion was 8 microm/10s taking an average of 41s to reach precast size. Where a post pattern fits tightly, airborne particle abrasion for 70s should reduce the casting sufficiently to accommodate the cement lute.

  3. Three-body abrasive wear characteristics under reciprocating motion of CFRP in vibrating environment

    SciTech Connect

    Teraoka, Sadakazu; Ishikawa, Ken-ichi; Nakagawa, Tatsuo

    1996-12-31

    Carbon fiber reinforced plastics (CFRP) has been widely used in industry because of their attractive mechanical characteristics. Such CFRP parts are invariably subjected to three-body wear due to small indentations and machine vibrations. In this study, the wear characteristics under the three-body condition and the abrasive wear of CFRP were investigated by using a vibrating environment and silicon carbide abrasive grains.

  4. Laboratory Measurements of Particulate Matter Concentrations from Asphalt Pavement Abrasion

    NASA Astrophysics Data System (ADS)

    Fullová, Daša; Đurčanská, Daniela

    2016-12-01

    The issue of emissions from road traffic is compounded by the fact that the number of vehicles and driven kilometres increase each year. Road traffic is one of the main sources of particulate matter and traffic volume is still increasing and has unpleasant impact on longevity of the pavements and the environment. Vehicle motions cause mechanical wearing of the asphalt pavement surface - wearing course by vehicle tyres. The contribution deals with abrasion of bituminous wearing courses of pavements. The asphalt mixtures of wearing courses are compared in terms of mechanically separated particulate matter. The samples of asphalt mixtures were rutted in wheel tracking machine. The particulate matter measurements were performed in laboratory conditions. The experimental laboratory measurements make it possible to sample particulates without contamination from exhaust emissions, abraded particles from vehicles, resuspension of road dust and climate affects. The contribution offers partial results of measurements on six trial samples of asphalt mixtures with different composition. It presents particulate matter morphology and the comparison of rutted asphalt samples in terms of PM mass concentrations and chemical composition.

  5. Is bovine dentine an appropriate substitute in abrasion studies?

    PubMed

    Wegehaupt, Florian J; Widmer, Raffaella; Attin, Thomas

    2010-04-01

    The study aimed to compare the wear behaviour of human and bovine dentine due to toothbrushing with different relative dentin abrasivity (RDA) toothpastes. Forty human and 40 bovine dentine samples were prepared from bovine lower incisors or human premolars roots, and baseline surface profiles were recorded. The samples were distributed to four groups (each group n = 10 human and 10 bovine samples) and brushed with fluoridated experimental toothpastes with different RDAs (group A: RDA 10, B: RDA 20, C: RDA 50, and D: RDA 100). Toothbrushing was performed in an automatic brushing machine with a brushing frequency of 60 strokes per minute and a brushing force of 2.5 N. After 2, 5, 10, and 25 min of toothbrushing, new surface profiles were recorded, and the dentine wear was calculated with a customized computer programme. The dentine wear of human and bovine dentine within the four groups was compared with unpaired t tests. No statistically significant difference was recorded for the dentine wear of human and bovine samples within the different groups.

  6. Neutralization of potential land mine hazards by abrasive waterjet use

    NASA Astrophysics Data System (ADS)

    Summers, David A.; Fossey, Robert D.; Thompson, S. J.

    1998-09-01

    A method of neutralizing landmines in which the integrity of the surrounding terrain is retained is herein described. High pressure waterjets which can be used to detect the presence of landmines can then be used to remove the soil and other cover in a plane immediately adjacent to and around the mine so that the side of the mine can be visually inspected through a remote television camera. At that time the flow of water is channeled through a line in which small particles of sand are added to the waterjet which is at a pressure of between 3,000 and 10,000 psi depending on the device which is used. Jet flow rates are on the order of 5 gpm depending on the nozzle configuration used. By bringing this abrasive stream in along a lateral plane through the mine it is possible to intersect, and neutralize, the fusing systems most likely to be used to initiate the charge, in a single pass. At higher flow rates, as the cut is made the jet will generate significant turbulence in the mine body, sufficient to remove a considerable quantity of the explosive which is resident within the mine at the same time as the mine is being dissected. The precision of cut achievable is shown by the longitudinal cutting into two parts of live detonators, as well as representative mine bodies.

  7. Abrasive waterjet cutting of high purity uranium metal: Topical report

    SciTech Connect

    Dravland, D.J.

    1988-01-01

    The Abrasive Waterjet Cutting process was evaluated to determine if the equivalent could be utilized for cutting uranium metal at the Feed Materials Production Center (FMPC). In the process, a thin stream of ultrahigh pressure water carried grit material through a designated piecepart. In order to be acceptable for use at the FMPC, the equipment must be cost effective, minimize waste, and be adaptableto operating in an enclosure, and improve health and safety conditions. Observation of the cutting process showed that health and safety aspects could be optimized with an enclosed ventilated system. Also the equipment can be easily automated. The cutting action produced sparks similar to the sparks caused by a grinding operation. The sparks are captured in a water container under the workpiece that not only catches the sparks, but also serves to dissipiate the stream of water and residues produced by the cut. Metallographic tests performed on the cut surface of the block of depleted uranium showed no contamination of the uranium metal and the surface finish. 2 figs.

  8. Relationships Between Abrasion Index and Shape Properties of Progressively Abraded Dolerite Railway Ballasts

    NASA Astrophysics Data System (ADS)

    Okonta, F. N.

    2014-07-01

    Sub-angular-shaped aggregates are used as rail foundation ballasts and must remain sub-angular during their service life time to maintain particle-particle interlocking, in order to ensure the stability of the rail line and prevent accidents by derailment. Here, the screening of dolerite quarry aggregates for use as railway foundation ballasts was investigated by employing simple digital image and chart methods. The average particle size ( d 50), flakiness index (FI), Los Angeles abrasion index (LAAI), sphericity (SPH) and roundness (RND) were determined for two batches of dolerite ballasts from the Rooikraal quarry in Johannesburg and Ngagane quarry in Newcastle. Thirty samples from each of the two batches of ballast were analysed. The ballasts were progressively abraded using a Los Angeles abrasion device and were analysed after each cycle of abrasion. A decrease in d 50 and an increase in FI with increased number of abrasion cycles were observed for both batches of dolerite ballast. The difference in the chart and digital image values of RND and SPH were marginal before abrasion; however, these differences increased with each abrasion cycle. The LAAI, d 50, mean RND and mean SPH correlated significantly and were found to have high regression coefficients. Thus, statistical models are proposed for the non-destructive routine screening of in-place ballasts in order to track marginal changes in aggregate shapes, facilitate ballast replacement programmes and avoid rail line instability.

  9. 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.

  10. [Grinding of titanium. 2. Commercial vitrified wheels made of alumina 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 vitrified wheels made of alumina abrasives, and their grinding performance was investigated. For cutting, the appropriate circumferential speed of the alumina wheels was about 700 m/min. A speed lower or higher than this yielded unfavorable grinding results, which were attributed to wheel loading or chemical attrition of the abrasive, respectively. The hard wheel made of the A abrasive was suitable for grinding of titanium, and moreover, the wheel of the WA abrasive was more suitable than that made of the A abrasive. Generally, the cutting rate of the alumina wheels was inferior to that of the silicon carbide ones investigated previously. Depression of the wheel against the work yielded unfavorable grinding results; the manner in which the wheel was moved over the work during grinding was very important, compared with the silicon carbide wheels. Although the wheel was moved over the work, the high circumferential speed of the wheel resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn. The grinding burn layer mainly consisted of a few microns-thick titanium oxide.

  11. Kinetic energy density and agglomerate abrasion rate during blending of agglomerates into powders.

    PubMed

    Willemsz, Tofan A; Hooijmaijers, Ricardo; Rubingh, Carina M; Tran, Thanh N; Frijlink, Henderik W; Vromans, Herman; van der Voort Maarschalk, Kees

    2012-01-23

    Problems related to the blending of a cohesive powder with a free flowing bulk powder are frequently encountered in the pharmaceutical industry. The cohesive powder often forms lumps or agglomerates which are not dispersed during the mixing process and are therefore detrimental to blend uniformity. Achieving sufficient blend uniformity requires that the blending conditions are able to break up agglomerates, which is often an abrasion process. This study was based on the assumption that the abrasion rate of agglomerates determines the required blending time. It is shown that the kinetic energy density of the moving powder bed is a relevant parameter which correlates with the abrasion rate of agglomerates. However, aspects related to the strength of agglomerates should also be considered. For this reason the Stokes abrasion number (St(Abr)) has been defined. This parameter describes the ratio between the kinetic energy density of the moving powder bed and the work of fracture of the agglomerate. The St(Abr) number is shown to predict the abrasion potential of agglomerates in the dry-mixing process. It appeared possible to include effects of filler particle size and impeller rotational rate into this concept. A clear relationship between abrasion rate of agglomerates and the value of St(Abr) was demonstrated.

  12. Bending and abrasion fatigue of common suture materials used in arthroscopic and open orthopedic surgery.

    PubMed

    Savage, Earle; Hurren, Christopher J; Slader, Simon; Khan, Lukman A K; Sutti, Alessandra; Page, Richard S

    2013-01-01

    In orthopedic surgery, the reattachment of tendon to bone requires suture materials that have stable and durable properties to allow time for healing at the tendon-bone interface. The suture, not rigidly restrained within the anchor eyelet, is free to move during surgery and potentially after surgery with limb motion. During such movement, the suture is subjected to bending and frictional forces that can lead to fatigue-induced failure. We investigated some common contemporary commercial number-two-grade suture materials and evaluated their resistance to bending abrasion fatigue and the consequent failure. Sutures were oscillated over a stainless steel wire at low frequency under load. Number of abrasion cycles to failure, changes in suture morphology, and fatigue-failure method was recorded for each material. Suture structure had a significant effect on abrasion resistance, with braided sutures containing large numbers of fine high tenacity core filaments performing 15-20 times better than other braided suture structures. Ultra high molecular weight polyethylene (UHMWPE) core filaments resisted bending abrasion failure better than other core materials due to the load spreading and abrasion resistance of these filaments. Sutures with UHMWPE cores also had high resistance to tensile failure. Limited correlation was observed between tensile strength and abrasion resistance.

  13. Gait Analysis and the Cumulative Gait Index (CGI): Translational Tools to Assess Impairments Exhibited by Rats with Olivocerebellar Ataxia

    PubMed Central

    Lambert, C.S.; Philpot, R.M.; Engberg, M.E.; Johns, B.E.; Kim, S.H.; Wecker, L.

    2014-01-01

    Deviations from ‘normal’ locomotion exhibited by humans and laboratory animals may be determined using automated systems that capture both temporal and spatial gait parameters. Although many measures generated by these systems are unrelated and independent, some may be related and dependent, representing redundant assessments of function. To investigate this possibility, a treadmill-based system was used to capture gait parameters from normal and ataxic rats, and a multivariate analysis was conducted to determine deviations from normal. Rats were trained on the treadmill at two speeds, and gait parameters were generated prior to and following lesions of the olivocerebellar pathway. Control (non-lesioned) animals exhibited stable hindlimb gait parameters across assessments at each speed. Lesioned animals exhibited alterations in multiple hindlimb gait parameters, characterized by significant increases in stride frequency, braking duration, stance width, step angle, and paw angle and decreases in stride, stance, swing and propulsion durations, stride length and paw area. A principal component analysis of initial hindlimb measures indicated 3 uncorrelated factors mediating performance, termed rhythmicity, thrust and contact. Deviation in the performance of each animal from the group mean was determined for each factor and values summed to yield the Cumulative Gait Index (CGI), a single value reflecting variation within the group. The CGI for lesioned animals increased 2.3-fold relative to unlesioned animals. This study characterizes gait alterations in laboratory rats rendered ataxic by destruction of the climbing fiber pathway innervating Purkinje cells and demonstrates that a single index can be used to describe overall gait impairments. PMID:25116252

  14. Tools and Technologies Needed for Conducting Planetary Field Geology While On EVA: Insights from the 2010 Desert RATS Geologist Crewmembers

    NASA Technical Reports Server (NTRS)

    Young, Kelsey; Hurtado, Jose M., Jr.; Bleacher, Jacob E.; Garry, W. Brent; Bleisath, Scott; Buffington, Jesse; Rice, James W., Jr.

    2011-01-01

    Observation is the primary role of all field geologists, and geologic observations put into an evolving conceptual context will be the most important data stream that will be relayed to Earth during a planetary exploration mission. Sample collection is also an important planetary field activity, and its success is closely tied to the quality of contextual observations. To test protocols for doing effective planetary geologic fieldwork, the Desert RATS (Research and Technology Studies) project deployed two prototype rovers for two weeks of simulated exploratory traverses in the San Francisco volcanic field of northern Arizona. The authors of this paper represent the geologist crewmembers who participated in the 2010 field test. We document the procedures adopted for Desert RATS 2010 and report on our experiences regarding these protocols. Careful consideration must be made of various issues that impact the interplay between field geologic observations and sample collection, including time management; strategies related to duplication of samples and observations; logistical constraints on the volume and mass of samples and the volume/transfer of data collected; and paradigms for evaluation of mission success. We find that the 2010 field protocols brought to light important aspects of each of these issues, and we recommend best practices and modifications to training and operational protocols to address them. Underlying our recommendations is the recognition that the capacity of the crew to "flexibly execute" their activities is paramount. Careful design of mission parameters, especially field geologic protocols, is critical for enabling the crews to successfully meet their science objectives.

  15. Mechanics of the pad-abrasive-wafer contact in chemical mechanical polishing

    NASA Astrophysics Data System (ADS)

    Bozkaya, Dincer

    2009-12-01

    In chemical mechanical polishing (CMP), a rigid wafer is forced on a rough, elastomeric polishing pad, while a slurry containing abrasive particles flows through the interface. The applied pressure on the wafer is carried partially by the 2-body pad-wafer contact (direct contact) and partially by the 3-body contact of pad, wafer and abrasive particles ( particle contact). The fraction of the applied pressure carried by particle contacts is an important factor affecting the material removal rate (MRR) as the majority of the material is removed by the abrasive particles trapped between the pad asperities and the wafer. In this thesis, the contact of a rough, deformable pad and a smooth, rigid wafer in the presence of rigid abrasive particles at the contact interface is investigated by using contact mechanics and finite element (FE) modeling. The interactions between the pad, the wafer and the abrasive particles are modeled at different scales of contact, starting from particle level interactions, and gradually expanding the contact scale to the multi-asperity contact of pad and wafer. The effect of surface forces consisting of van der Waals and electrical double layer forces acting between the wafer and the abrasive particles are also investigated in this work. The wear rate due to each abrasive particle is calculated based on the wafer-abrasive particle contact force, and by considering adhesive and abrasive wear mechanisms. A passivated layer on the wafer surface with a hardness and thickness determined by the chemical effects is modeled, in order to characterize the effect of chemical reactions between slurry and wafer on the MRR. The model provides accurate predictions for the MRR as a function of pad related parameters; pad elastic modulus, pad porosity and pad topography, particle related parameters; particle size and concentration, and slurry related parameters; slurry pH, thickness and hardness of the passivated surface layer of wafer. A good qualitative

  16. Influence of Diamond Sono-Abrasion, Air-Abrasion and Er:YAG Laser Irradiation on Bonding of Different Adhesive Systems to Dentin

    PubMed Central

    de Oliveira, Marcelo Tavares; de Freitas, Patrícia Moreira; de Paula Eduardo, Carlos; Ambrosano, Glaucia Maria Bovi; Giannini, Marcelo

    2007-01-01

    Objectives Different surface treatments may affect bonding performance of adhesive systems to dentin. This study evaluated the influence of different methods of surface treatment on adhesion of bonding agents to dentin. Methods Dentin surfaces abraded with #600-grit SiC paper were used as control. Three methods of surface treatment (sono-abrasion, air-abrasion and Er:YAG laser irradiation) were used under specific parameters. Four adhesive systems (Tyrian, Clearfil SE Bond, Unifil Bond and Single Bond) were applied to treated surfaces, according to the manufacturers’ instructions. Composite blocks were built on bonded surfaces, then restored teeth were vertically and serially sectioned to obtain bonded slices for interfacial micromorphologic analysis or to produce beam specimens for μ-TBS bond test. Data were analyzed with two-way ANOVA and Tukey test at a significance level of 5%. Results The results indicated that the preparation of dentin with sono-abrasion or laser did not affect the bond strength, while the preparation of dentin with SiC paper and air-abrasion influenced the bond strength for some systems. A clear difference of the preparation of dentin surfaces and formation of hybrid layer and resin tags were noted. Conclusion Bonding effectiveness of both the etch-and-rinse and the self-etch adhesives can be influenced by different methods of dentin preparation. PMID:19212560

  17. Head mounted DLP for visual stimulation in freely moving rats: a novel tool for visual neuroscience research

    NASA Astrophysics Data System (ADS)

    Mandel, Yossi; Arens-Arad, Tamar; Farah, Nairouz; Zlotnik, Alex; Zalevsky, Zeev

    2015-03-01

    Novel technologies are constantly under development for vision restoration in blind patients. In some of these techniques, such as photodiode implants or optogenetics based treatment, a glasses mounted optical projection system projects the visual scene onto the retina. The desired projection system is characterized by a relatively high power density, a localized retinal stimulation area and compatibility for wavelengths that are specific for the technology at hand. The challenges of obtaining such a projection system are not only limited by developing the tools and the apparatus for testing the visual performance of artificial retina, but also devising the technique and the methodology for training and testing the behaving animals using this tool. Current research techniques used for evaluation of visual function in behaving animals utilize computer screens for retinal stimulation, and therefore do not fulfill the requirements of the evaluation of retinal implant performance or optogenetics based treatment (inefficient power and no wavelength flexibility). In the following work we will present and evaluate a novel projection system that is suited for behavioral animal studies and meet the requirements for artificial retinal stimulation. The proposed system is based on a miniature Digital Mirror Device (DMD) for pattern projection and a telescope for relaying the pattern directly onto the animal eye. This system facilitates the projection of patterns with high spatial resolution at high light intensities with the desired wavelength and may prove to be a vital tool in natural and artificial vision performance research in behaving animals.

  18. Behavior of HVOF WC-10Co4Cr Coatings with Different Carbide Size in Fine and Coarse Particle Abrasion

    NASA Astrophysics Data System (ADS)

    Ghabchi, Arash; Varis, Tommi; Turunen, Erja; Suhonen, Tomi; Liu, Xuwen; Hannula, S.-P.

    2010-01-01

    A modified ASTM G 65 rubber wheel test was employed in wet and dry conditions using 220 nm titania particles and 368 μm sand particles, respectively. Both tests were conducted on WC-CoCr coatings produced with two powders with different carbide grain sizes (conventional and sub-micron) to address the effect of carbide size and abrasive medium characteristics on the wear performance. The same spot before and after the wet abrasion wear testing was analyzed in detail using SEM to visualize wear mechanisms. It was shown that the wear mechanism depends on the relative size of the carbide and abrasive particles. Wear mechanisms in dry sand abrasion were studied by analyzing the single scratches formed by individual abrasive particles. Interaction of surface open porosity with moving abrasive particles causes formation of single scratches. By tailoring the carbide size, the wear performance can be improved.

  19. Performance of Flame Sprayed Ni-WC Coating under Abrasive Wear Conditions

    NASA Astrophysics Data System (ADS)

    Harsha, S.; Dwivedi, D. K.; Agarwal, A.

    2008-02-01

    This paper describes the influence of a post spray heat treatment on the microstructure, microhardness and abrasive wear behavior of the flame sprayed Ni-WC (EWAC 1002 ET) coating deposited on the mild steel. Coatings were deposited by using an oxy-acetylene flame spraying torch (Superjet Eutalloy L & T, India). The wear behavior of the coating was evaluated using a pin on disc wear system against SiC abrasive medium of 120 and 600 grades at 5, 10, 15, and 20 N normal load. Results revealed that the influence of normal load on wear is governed by the microstructure, hardness and abrasive grit size. The heat treatment increased average microhardness of the coating. However, it was found that the hardness does not correctly indicate the abrasive wear resistance of Ni-WC coating in an as sprayed and heat treated condition. The heat treatment of the coating improved its abrasive wear resistance against fine abrasive medium while the wear resistance against coarse abrasive was found to be a function of a normal load. At low-normal load (5 and 10 N) the heat treated coating showed lower-wear rate than as spayed coating while at high-normal loads (15 and 20 N) heat treated coating was subjected to higher-wear rate than as sprayed coating. In general, an increase in normal load increased the wear rate. The scanning electron microscopy study indicated that the wear largely takes place by groove formation and scoring of eutectic matrix and the fragmentation of the carbide particles.

  20. Investigating selective transport and abrasion on an alluvial fan using quantitative grain size and shape analysis

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Selective sorting and abrasion are the two major fluvial processes that are attributed to the downstream fining of sediments in rivers and alluvial fans. Selective transport is the process by which smaller grains are preferentially transported downstream while larger grains are deposited closer to the source. Abrasion is defined by the production of fine sediments and sand that occurs by saltation of gravel, where particle-to-particle collisions supply the energy required to break apart grains. We hypothesize that abrasion results in the gradual fining of large grains and the production of fine sands and silts, while sorting accounts for the differences in transport of these two grain-size fractions produced from abrasion, thereby creating the abrupt gravel-sand transition observed in many channel systems. In this research, we explore both selective transport and abrasion processes on the Dog Canyon alluvial fan near Alamogordo, New Mexico. We complete an extensive grain size analysis down the main channel of the fan employing an image-based technique that utilizes an autocorrelation process. We also characterize changes in grain shape using standard shape parameters, as well as Fourier analysis, which allows the study of contributions of grain roughness on a variety of length scales. Sorting appears to dominate the upper portion of the fan; the grain-size distribution narrows moving downstream until reaching a point of equal mobility, at which point sorting ceases. Abrasion exerts a subtle but persistent effect on grains during transport down the fan. Shape analysis reveals that particles become more rounded by the removal of small-scale textural features, a process that is expected to only modestly influence grain size of gravel, but should produce significant quantities of sand. This study provides a better understanding of the importance of grain abrasion and sorting on the downstream fining of channel grains in an alluvial fan, as well as an improved knowledge

  1. 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

  2. A Study of Soil Tillage Tools from Boronized Sintered Iron

    NASA Astrophysics Data System (ADS)

    Yazici, A.; Çavdar, U.

    2017-03-01

    Acomparative analysis of the properties of boronized sintered iron and quenched steels 30MnB5, 28MnCrB5 used for making soil tillage tools is performed. The microstructure, phase composition, hardness and strength characteristics of the materials are studied. The composition of the boride phase formed in the sintered iron after boronizing is determined by an x-ray method. The losses to abrasive wear are evaluated with the help of a device containing a special bin with a sample of abrasive soil.

  3. 'RAT' Hole on 'Pilbara' (post-RAT)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The Mars Exploration Rover Opportunity broke its own record for the deepest hole ground into a rock on another planet with a 7.2-millimeter (about 0.28-inch) grind on the rock 'Pilbara,' on the rover's 86th sol on Mars.

    This image is a panoramic camera picture highlighting the hole left by the rock abrasion tool after two hours and 16 minutes of grinding. The hole is 7.2 millimeters (about 0.28 inches) deep and 4.5 centimeters (about 1.8 inches) in diameter. The tool swept the hole clean after grinding, leaving the ring of cuttings around the hole. When this image was taken, the abraded area was mostly shaded by the rover, with the sun peeking through the joint that connects the front solar panel to the body of the rover.

    The team has developed a new approach to commanding the rock abrasion tool that allows for more aggressive grinding parameters. The tool is now programmed, in the event of a stall, to retreat from its target and attempt to grind again. This allows the grinder to essentially reset itself instead of aborting its sequence altogether and waiting for further commands from rover planners.

  4. Infrared Spectroscopy as a Tool to Study the Antioxidant Activity of Polyphenolic Compounds in Isolated Rat Enterocytes

    PubMed Central

    Barraza-Garza, Guillermo; Castillo-Michel, Hiram; de la Rosa, Laura A.; Martinez-Martinez, Alejandro; Pérez-León, Jorge A.; Cotte, Marine; Alvarez-Parrilla, Emilio

    2016-01-01

    The protective effect of different polyphenols, catechin (Cat), quercetin (Qc) (flavonoids), gallic acid (GA), caffeic acid (CfA), chlorogenic acid (ChA) (phenolic acids), and capsaicin (Cap), against H2O2-induced oxidative stress was evaluated in rat enterocytes using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) Spectroscopy and Fourier Transform Infrared Microspectroscopy (FTIRM), and results were compared to standard lipid peroxidation techniques: conjugated dienes (CD) and Thiobarbituric Acid Reactive Substances (TBARS). Analysis of ATR-FTIR and FTIRM spectral data allowed the simultaneous evaluation of the effects of H2O2 and polyphenols on lipid and protein oxidation. All polyphenols showed a protective effect against H2O2-induced oxidative stress in enterocytes, when administered before or after H2O2. Cat and capsaicin showed the highest protective effect, while phenolic acids had weaker effects and Qc presented a mild prooxidative effect (IR spectral profile of biomolecules between control and H2O2-treated cells) according to FTIR analyses. These results demonstrated the viability to use infrared spectroscopy to evaluate the oxidant and antioxidant effect of molecules in cell systems assays. PMID:27213031

  5. Is bovine dentine an appropriate substitute for human dentine in erosion/abrasion tests?

    PubMed

    Wegehaupt, F; Gries, D; Wiegand, A; Attin, T

    2008-05-01

    The study aimed to compare the dentine wear of primary and permanent human and bovine teeth because of erosion/abrasion and evaluate if bovine dentine is an appropriate substitute for human dentine in further erosion/abrasions tests. Dentine samples from deciduous molars and human third molars as well as from calves' and cattle's lower incisors were prepared and baseline surface profiles were recorded. Each day all samples were demineralized in 1% citric acid, tooth brushed with 100 brushing strokes with toothpaste slurry and stored in artificial saliva for the rest of the day. This cycle was run for 20 days. Afterwards, new surface profiles were recorded and dentine wear was calculated by a customized computer program. Dentine wear because of erosion/abrasion was not statistically, significantly different for human third molars and cattle's lower incisors (P = 0.7002). The dentine wear because of erosion/abrasion of deciduous molars and calves' lower incisors was significantly different (P < 0.0000). No statistically significant difference in the dentine wear of human third molars and cattle's lower incisors was observed, so that the use of cattle's lower incisors as substitute for adult human teeth for further investigations in erosion/abrasion studies could be accepted.

  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.

  7. Finishing of display glass for mobile electronics using 3M Trizact diamond tile abrasive pads

    NASA Astrophysics Data System (ADS)

    Zheng, Lianbin; Fletcher, Tim; Na, Tee Koon; Sventek, Bruce; Romero, Vince; Lugg, Paul S.; Kim, Don

    2010-10-01

    This paper will describe a new method being used during the finishing of glass displays for mobile electronics including mobile hand held devices and notebook computers. The new method consists of using 3M TrizactTM Diamond Tile Abrasive Pads. TrizactTM Diamond Tile is a structured fixed abrasive grinding technology developed by 3M Company. The TrizactTM Diamond Tile structured abrasive pad consists of an organic (polymeric binder) - inorganic (abrasive mineral, i.e., diamond) composite that is used with a water-based coolant. TrizactTM Diamond Tile technology can be applied in both double and single side grinding applications. A unique advantage of TrizactTM Diamond Tile technology is the combination of high stock removal and low sub-surface damage. Grinding results will be presented for both 9 micron and 20 micron grades of TrizactTM Diamond Tile abrasive pads used to finish several common display glasses including Corning GorillaTM glass and Soda Lime glass.

  8. 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.

  9. Assessment of the abrasion potential of pesticide-treated seeds using the Heubach test

    PubMed Central

    Zwertvaegher, Ingrid K. A.; Foqué, Dieter; Devarrewaere, Wouter; Verboven, Pieter; Nuyttens, David

    2016-01-01

    ABSTRACT During sowing of pesticide-treated seeds, pesticide-laden dust and abraded seed particles may be emitted to the environment, possibly leading to environmental contamination and posing health risks. In many countries there is currently no legislation concerning the acceptable amount of dust of treated seeds. This study aimed to gain insight in the abrasion potential of available pesticide-treated seeds and its associated factors. The abrasion potential of 45 seed samples of 7 different species (viz. sugar beet, oat, barley, wheat, spelt, pea, and maize) was determined using the Heubach test and amounts of dust were expressed as g 100 kgseeds −1, g 100,000 seeds−1, and g ha−1. The abrasion potential fell generally within the boundaries of maximum permissible values adopted by different countries. Species, seed treatment company, number of active ingredient (AIs) and combination of AIs had significant effects on the abrasion potential, whereas little or no effect of agitation and conservation was found. However, species were situated differently with respect to each other depending on the unit in which the abrasion potential was expressed. A standard unit that takes into account the species’ seed rate is suggested to give the fairest assessment of dust drift risk and would allow international comparison. PMID:27812241

  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. Assessment of the abrasion potential of pesticide-treated seeds using the Heubach test.

    PubMed

    Zwertvaegher, Ingrid K A; Foqué, Dieter; Devarrewaere, Wouter; Verboven, Pieter; Nuyttens, David

    2016-10-01

    During sowing of pesticide-treated seeds, pesticide-laden dust and abraded seed particles may be emitted to the environment, possibly leading to environmental contamination and posing health risks. In many countries there is currently no legislation concerning the acceptable amount of dust of treated seeds. This study aimed to gain insight in the abrasion potential of available pesticide-treated seeds and its associated factors. The abrasion potential of 45 seed samples of 7 different species (viz. sugar beet, oat, barley, wheat, spelt, pea, and maize) was determined using the Heubach test and amounts of dust were expressed as g 100 kgseeds(-1), g 100,000 seeds(-1), and g ha(-1). The abrasion potential fell generally within the boundaries of maximum permissible values adopted by different countries. Species, seed treatment company, number of active ingredient (AIs) and combination of AIs had significant effects on the abrasion potential, whereas little or no effect of agitation and conservation was found. However, species were situated differently with respect to each other depending on the unit in which the abrasion potential was expressed. A standard unit that takes into account the species' seed rate is suggested to give the fairest assessment of dust drift risk and would allow international comparison.

  12. 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.

  13. 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.; 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.

  14. 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.

  15. Estimation of the abrasive wear coefficient in Lillehei-Kaster cardiac valve prostheses.

    PubMed

    Reif, T H; Silver, M D; Koppenhoefer, H; Huffstutler, M C

    1986-01-01

    An approximate hemodynamic theory, which predicts the opening dynamics of the Lillehei-Kaster heart valve, is used in conjunction with an abrasive wear model to predict the wear process on the shields. The hemodynamic theory predicts markedly different opening dynamics between the mitral and aortic positions and is shown to give excellent correlation with the experimental results of other investigations. The abrasive wear model is also shown to give excellent correlation with the experiments of others when the abrasive wear coefficient is taken as k = 6.4 X 10(-6). The theoretical results of this effort and the experimental data from clinical explants of other investigators is used to predict that occluder dislodgement is unlikely in less than 90 yr for either the mitral or aortic positions (for a mean cardiac output of 3.8 l.min-1 and a mean heart rate of 70 beats min-1).

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Understanding Characteristic of Abrasion of Refractory Lining Caused by Bath Oscillation in BOF Steelmaking

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Li, Mingming; Kuang, S. B.; Zou, Zongshu

    2016-12-01

    This paper presents a numerical study of the refractory abrasion occurring widely inside basic oxygen furnace (BOF) steelmaking. The mechanism of refractory abrasion is examined numerically referring to the bath oscillation with regard to flows, turbulence and wall shear stress inside a BOF. The simulation results reveal that the refractory abrasion tends to occur on the wall region between the slag/atmosphere and slag/metal interfaces due to the oscillation of the bath in the blowing process, which generally promotes slag-line erosion. The decreased nozzle angle, and either increased lance height or operation pressure can lead to more serious refractory erosion that occurs more likely during the slag-making period in the operation of BOF.

  2. A study of the abrasive resistance of metal alloys with applications in dental prosthetic fixators.

    PubMed

    Gil, F J; Fernández, E; Manero, J M; Planell, J A; Sabrià, J; Cortada, M; Giner, L

    1995-01-01

    Wear is one of the main surface failure mechanisms in materials and it will play a leading role in substitutive dental biomaterials. The aim of the present study is to compare the abrasive wear of different metallic materials used in dental applications. The results show that the abrasive wear of alloys based on precious metals such as Pt, Pd, Au and Ag is higher than for Ti and Ti based alloys. The alloy with the highest wear resistance is the Co-Cr which exhibits as well the highest hardness and Young's modulus. Since the method corresponds to a well-established abrasive wear standard, the behaviour of the different materials can be easily compared.

  3. 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.

  4. Design of erosion/abrasion studies--insights and rational concepts.

    PubMed

    Wiegand, Annette; Attin, Thomas

    2011-01-01

    In vitro and in situ studies modelling the wear of dental hard tissues due to erosion and abrasion are characterised by a high variation in study designs and experimental parameters. Based on a summary of the existing protocols, the present review aimed to describe and discuss the parameters which must be carefully considered in erosion-abrasion research, especially when it is intended to simulate clinical conditions. Experimental characteristics and parameters were retrieved from a total of 42 in vitro and 20 in situ studies. The key experimental characteristics included parameters of erosion (duration and pH) and abrasion (duration, kinds of toothbrush and toothpaste, brushing force, and time point) as well as co-factors (e.g. dental hard tissue). The majority of studies used models with alternating erosion/abrasion treatments intended to simulate clinical conditions, while other studies exaggerated clinical conditions intentionally, often using only a single erosion/abrasion treatment. Both in vitro and in situ models shared a high level of standardisation, but several studies showed a trend to severe erosion (e.g. >5 min/cycle) or extensive brushing (e.g. >100 brushing strokes/cycle) at a high frequency and repetition rate. Thus, studies often tend to produce a higher amount of wear than in the clinical situation, especially as modifying biological factors (e.g. the dilution of the erosive solution by saliva and the protective effect of the pellicle) cannot be simulated adequately. With respect to the existing models, it seems advisable to diminish duration and frequency of erosion and abrasion to more realistic clinical conditions when the everyday situation is to be simulated. Experimental parameters must be chosen with care to ensure that the problem is investigated in an appropriate mode at standardised conditions and with adequate measuring systems to allow prediction of clinical outcomes.

  5. 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.

  6. Microstructure Evolution and Abrasive Wear Behavior of Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Hadke, Shreyash; Khatirkar, Rajesh K.; Shekhawat, Satish K.; Jain, Shreyans; Sapate, Sanjay G.

    2015-10-01

    This paper investigates the effect of quenching and aging treatment on microstructure and abrasive wear of Ti-6Al-4V alloy. The as-received alloy was solution treated at 1339 K, then oil quenched, followed by aging at 823 K for 4 h (14,400 s). The microstructures of as-received and quench-aged specimens were characterized by using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and electron backscattered diffraction techniques. The as-received specimen consisted of very fine α grains (average grain size 2 μm) with β phase uniformly dispersed throughout. The microstructure of the quench-aged specimen showed α plates (formed by the decomposition of α' during aging). The β phase precipitated out of α' martensite during aging and hence was dispersed uniformly in the α matrix. Ti-6Al-4V alloy was quench-aged to achieve maximum hardness with a view that the increased hardness would lead to an improvement in abrasive wear behavior. Two-body abrasive wear tests were carried out on the as-received and quench-aged specimens using pin-on-disk apparatus with SiC as abrasive media (150-grit size). The effect of sliding distance and normal load on the abrasive wear behavior was studied. The wear resistance of the as-received specimen was greater than that of quench-aged specimen, while hardness of the as-received specimen was lower than that of quench-aged specimen. The abrasive wear behavior of Ti-6Al-4V alloy has been explained based on morphology/microstructure of the alloy and the associated wear mechanism(s).

  7. Methods for atomistic abrasion simulations of laterally periodic polycrystalline substrates with fractal surfaces

    NASA Astrophysics Data System (ADS)

    Eder, S. J.; Bianchi, D.; Cihak-Bayr, U.; Gkagkas, K.

    2017-03-01

    In this work we discuss a method to generate laterally periodic polycrystalline samples with fractal surfaces for use in molecular dynamics simulations of abrasion. We also describe a workflow that allows us to produce random lateral distributions of simple but realistically shaped hard abrasive particles with Gaussian size distribution and random particle orientations. We evaluate some on-the-fly analysis and visualization possibilities that may be applied during a molecular dynamics simulation to considerably reduce the post-processing effort. Finally, we elaborate on a parallelizable post-processing approach to evaluating and visualizing the surface topography, the grain structure and orientation, as well as the temperature distribution in large atomistic systems.

  8. 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.

  9. Water jet and abrasive water jet cutting of unidirectional graphite/epoxy composite

    NASA Astrophysics Data System (ADS)

    Ramulu, M.; Arola, D.

    1993-06-01

    Unidirectional graphite/epoxy composite material has been machined by water jet and abrasive water jet cutting processes. Topography and morphology of the machined surfaces were evaluated with surface profilometry and scanning electron microscopy. The surface characteristics in terms of roughness and the micromechanisms of material removal for both processes were analyzed and compared. Abrasive water jet surface characteristics of graphite/epoxy were found to be significantly different from those of the water jet cutting process and micromechanical behavior of material removal was strongly dependent on the fiber orientation.

  10. Impact of Abrasion on Mass Loss and Surface Appearance of Woven Fabrics Made with Injected Slub Yarn in Weft

    NASA Astrophysics Data System (ADS)

    Ray, Nemai Chandra; Mukhopadhyay, Arunangshu; Midha, Vinay Kumar

    2016-10-01

    Fancy yarn fabrics are susceptible to abrasive damage during washing and usage but the extent of damage varies with construction and type of fabric. In the present study, effect of different slub parameters viz. slub length, slub thickness and slub frequency of single base injected slub yarn on abrasive damage of woven fabrics has been studied when injected slub yarns are used in weft only. Abrasive damage has been assessed by two ways using loss in fabric mass and deterioration in fabric appearance due to abrasion. These two techniques provide entirely different effect of injected slub yarn parameters on abrasive damage of woven fabric. Fabric abrasion damage in terms of mass loss is not affected by slub thickness and damage is least when both slub length and slub frequency are at central/medium level. Under visual assessment it is observed that all the slub parameters have significant influence on abrasive damage of woven fabric. It is possible to have lower damage in surface appearance in spite of higher mass loss of fabric due to abrasion.

  11. NK cells are necessary for recovery of corneal CD11c+ dendritic cells after epithelial abrasion injury

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mechanisms controlling CD11c(+) MHCII(+) DCs during corneal epithelial wound healing were investigated in a murine model of corneal abrasion. Selective depletion of NKp46(+) CD3- NK cells that normally migrate into the cornea after epithelial abrasion resulted in >85% reduction of the epithelial CD1...

  12. 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.

  13. 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.

  14. Core-Cutoff Tool

    NASA Technical Reports Server (NTRS)

    Gheen, Darrell

    2007-01-01

    A tool makes a cut perpendicular to the cylindrical axis of a core hole at a predetermined depth to free the core at that depth. The tool does not damage the surrounding material from which the core was cut, and it operates within the core-hole kerf. Coring usually begins with use of a hole saw or a hollow cylindrical abrasive cutting tool to make an annular hole that leaves the core (sometimes called the plug ) in place. In this approach to coring as practiced heretofore, the core is removed forcibly in a manner chosen to shear the core, preferably at or near the greatest depth of the core hole. Unfortunately, such forcible removal often damages both the core and the surrounding material (see Figure 1). In an alternative prior approach, especially applicable to toxic or fragile material, a core is formed and freed by means of milling operations that generate much material waste. In contrast, the present tool eliminates the damage associated with the hole-saw approach and reduces the extent of milling operations (and, hence, reduces the waste) associated with the milling approach. The present tool (see Figure 2) includes an inner sleeve and an outer sleeve and resembles the hollow cylindrical tool used to cut the core hole. The sleeves are thin enough that this tool fits within the kerf of the core hole. The inner sleeve is attached to a shaft that, in turn, can be attached to a drill motor or handle for turning the tool. This tool also includes a cutting wire attached to the distal ends of both sleeves. The cutting wire is long enough that with sufficient relative rotation of the inner and outer sleeves, the wire can cut all the way to the center of the core. The tool is inserted in the kerf until its distal end is seated at the full depth. The inner sleeve is then turned. During turning, frictional drag on the outer core pulls the cutting wire into contact with the core. The cutting force of the wire against the core increases with the tension in the wire and

  15. 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...

  16. 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.

  17. High stress abrasive wear behavior of some hardfaced surfaces produced by thermal spraying

    NASA Astrophysics Data System (ADS)

    Jha, A. K.; Gachake, Arati; Prasad, B. K.; Dasgupta, Rupa; Singh, M.; Yegneswaran, A. H.

    2002-02-01

    Steel surfaces were thermally sprayed with nickel chromium boron (NCB) powder (with and without tungsten carbide) using an oxy-acetylene torch. The sprayed (hard) surfaces and substrate were characterized for abrasive wear properties. Test parameters such as load and sliding distance were varied. A significant improvement in the abrasive wear resistance (inverse of wear rate) was noted for the thermally sprayed surfaces as compared to that of the substrate. Wear surfaces, subsurface regions, and debris were examined in order to ascertain the operating wear mechanisms. Substrate (mild steel), because of its low hardness, suffered severe wear through the cutting, ploughing, and wedging action of the hard abrasive (silicon carbide). Deep cuts on the worn surface, a bulky transfer layer, subsurface cracks, and large-size debris were observed. However, wear was reduced due to high hardness of the layer of NCB powder on the substrate, which resisted the penetration of abrasive into the surface. Presence of tungsten carbide in the layer of NCB powder further reduced the wear of the corresponding specimen because of very high hardness of the tungsten carbide. Shallow wear grooves and finer debris were observed for the NCB coating with and without tungsten carbide. Cutting was the predominating wear mechanism in the case of coatings.

  18. 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.

  19. 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.

  20. Rapid prototyping of silicon structures by aid of laser and abrasive-jet machining

    NASA Astrophysics Data System (ADS)

    Kruusing, Arvi; Leppaevuori, Seppo; Uusimaki, Antti; Uusimaki, Matti

    1999-03-01

    Rapid prototyping of silicon microstructures for fluidic devices using laser machining in water and abrasive-jet machining through mask is described. For laser machining a Q-switched 1-2 W 1 kHz pulsed Nd:YAG laser beam and 60 mJ XeCl excimer laser beam were used. The laser beam was scanned along the silicon surface at speeds 0.1-2 mm/s. Using excimer laser, the silicon nitride layer was patterned for subsequent chemical etching. Nd:YAG laser was used for fabrication of cavities and channels of depth down to 200 micrometers . Comparison of Nd:YAG laser machining of silicon in air and in water has been performed. Machining in water yields more even surfaces and there is no debris. By abrasive jet of velocity approximately 200 m/s and abrasive feed rate of 0.4 g/s, the silicon was eroded at speed of 40 micrometers /min. Several masking materials were compared, whereby a styrene based glue was found to have the best abrasion resistivity. The polymer masks were spun on the surface and patterned by excimer laser point or by knife. The described fabrication methods were used for making the fluid channels and chambers in silicon and for releasing silicon nitride and oxide films.

  1. 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.

  2. 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...

  3. 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.

  4. Water and abrasive jetting, and mechanical techniques expedite hard rock drilling

    SciTech Connect

    Kolle, J.J.

    1998-04-20

    Construction activities that require the placement of gas, electrical, or communication utilities in hard rock will benefit from lightweight systems capable of precisely drilling short, constant-radius arcs. Existing mechanical drilling systems are capable of drilling shallow directional holes, but the equipment is heavy, drilling rates are low, and costs are high. A comparison of approaches for rapidly drilling small-diameter (25--50 mm) and near-surface holes along a short-radius (30 m) arc, in a variety of hard rock types, is describes. Four approaches are considered: (1) rotary diamond drilling with a downhole motor; (2) ultra-high pressure (UHP) water jet drilling; (3) mechanically assisted UHP water jet drilling; and (4) abrasive jet drilling -- abrasive water jet and abrasive slurry jet. Data relating mechanical and hydraulic drilling parameters for each approach were compiled from literature and drilling tests for all four techniques. The drilling data are summarized in a common format to provide direct drilling efficiency comparisons for: jet pressure and hydraulic power, and thrust and torque requirements and abrasive feed.

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. An in vitro evaluation of selective demineralised enamel removal using bio-active glass air abrasion.

    PubMed

    Banerjee, Avijit; Pabari, Hiten; Paolinelis, George; Thompson, Ian D; Watson, Timothy F

    2011-12-01

    Unnecessary over-preparation of carious enamel often occurs clinically during operative caries management. The working hypothesis to be investigated in this study is the potential for bio-active glass air abrasion to remove selectively only demineralised enamel in artificial enamel lesions when compared to equivalent alumina air abrasion, so potentially minimising cavity over-preparation. Bisected artificial, paired smooth surface enamel lesions on ethics-approved, extracted sound human molars were created and subsequently air abraded with 27 μm alumina (n = 19) and bio-active glass (n = 19). The difference between pre-operative lesion boundary and post-operative cavity margin was calculated following optical confocal fluorescent assessment of the lesion boundary. Data indicated mean% over-preparation (sound enamel removal) of 176% with alumina and 15.2% for bio-active glass (p = 0.005). Bio-active glass abrasion removed completely the demineralised enamel from artificial lesions with clinically insignificant over-preparation of sound tissue, indicating technique selectivity towards grossly demineralised enamel. Alumina air abrasion resulted in substantial enamel removal in both sound and demineralised tissues indicating the operator selectivity required to use the techniques effectively in clinical practice.

  11. 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...

  12. Comparison of dry wear characteristics of two abrasion-resistant steels: Q/T C1095 and 15B37H

    SciTech Connect

    Sim, G.; Tandon, K.N.; Iqbal, K.; Wang, Y.

    1995-10-01

    The dry reciprocating wear characteristics of two abrasion-resistant steels, C1095 and 15B37H, against an abrasive material were studied. Results showed that abrasive wear and surface fatigue were the primary wear mechanisms. The wear failure of the steels was related to frictional softening during wear.

  13. 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

  14. Numerical modelling of tool wear in turning with cemented carbide cutting tools

    SciTech Connect

    Franco, P.; Estrems, M.; Faura, F.

    2007-04-07

    A numerical model is proposed for analysing the flank and crater wear resulting from the loss of material on cutting tool surface in turning processes due to wear mechanisms of adhesion, abrasion and fracture. By means of this model, the material loss along cutting tool surface can be analysed, and the worn surface shape during the workpiece machining can be determined. The proposed model analyses the gradual degradation of cutting tool during turning operation, and tool wear can be estimated as a function of cutting time. Wear-land width (VB) and crater depth (KT) can be obtained for description of material loss on cutting tool surface, and the effects of the distinct wear mechanisms on surface shape can be studied. The parameters required for the tool wear model are obtained from bibliography and experimental observation for AISI 4340 steel turning with WC-Co cutting tools.

  15. The potential of deciduous and permanent bovine enamel as substitute for deciduous and permanent human enamel: Erosion-abrasion experiments.

    PubMed

    Attin, Thomas; Wegehaupt, Florian; Gries, David; Wiegand, Annette

    2007-10-01

    Aim of the present study was to compare toothbrushing abrasion of eroded human and bovine enamel utilizing a toothpaste slurry. The surfaces of each 36 teeth from cattle and calves and from each 36 human wisdom teeth and deciduous teeth were polished. Each 12 specimens from the respective tooth type were used for assessing toothbrushing abrasion only (A), erosion only (E) and the combination of erosion and toothbrushing abrasion (EA). The EA samples were subjected to 20 cycles comprising a demineralization/remineralization procedure directly followed by toothbrushing abrasion (100 strokes, 300 g load, toothpaste slurry: 3 ml artificial saliva mixed with 1g dentifrice). Demineralization in form of erosion was performed with 1% citric acid (1 min), remineralization with artificial saliva (15 min). Between the cycles, the samples were stored in artificial saliva. Wear of the treated surfaces with reference to untreated areas was determined profilometrically. The samples subjected to abrasion only (A) did not show a significantly different wear between the different kinds of teeth. The comparisons of substance loss between teeth of different species revealed that hard tissue loss of the human deciduous teeth was significantly lower as compared to calves' teeth after both erosion and erosion-abrasion. Also, both erosion only and erosion-abrasion caused higher enamel loss in cattle's teeth than in human wisdom teeth. It is concluded that human eroded enamel offers better resistance against brushing than bovine enamel.

  16. Diamond Sheet: A new diamond tool material

    NASA Technical Reports Server (NTRS)

    Mackey, C. R.

    1982-01-01

    Diamond sheet is termed a diamond tool material because it is not a cutting tool, but rather a new material from which a variety of different tools may be fabricated. In appearance and properties, it resembles a sheet of copper alloy with diamond abrasive dispersed throughout it. It is capable of being cut, formed, and joined by conventional methods, and subsequently used for cutting as a metal bonded diamond tool. Diamond sheet is normally made with industrial diamond as the abrasive material. The metal matrix in diamond sheet is a medium hard copper alloy which has performed well in most applications. This alloy has the capability of being made harder or softer if specific cutting conditions require it. Other alloys have also been used including a precipitation hardened aluminum alloy with very free cutting characteristics. The material is suitable for use in a variety of cutting, surfacing, and ring type tools, as well as in such mundane items as files and sandpaper. It can also be used as a bearing surface (diamond to diamond) and in wear resistant surfaces.

  17. Validation of Proposed Metrics for Two-Body Abrasion Scratch Test Analysis Standards

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    Abrasion of mechanical components and fabrics by soil on Earth is typically minimized by the effects of atmosphere and water. Potentially abrasive particles lose sharp and pointed geometrical features through erosion. In environments where such erosion does not exist, such as the vacuum of the Moon, particles retain sharp geometries associated with fracturing of their parent particles by micrometeorite impacts. The relationship between hardness of the abrasive and that of the material being abraded is well understood, such that the abrasive ability of a material can be estimated as a function of the ratio of the hardness of the two interacting materials. Knowing the abrasive nature of an environment (abrasive)/construction material is crucial to designing durable equipment for use in such surroundings. The objective of this work was to evaluate a set of standardized metrics proposed for characterizing a surface that has been scratched from a two-body abrasion test. This is achieved by defining a new abrasion region termed Zone of Interaction (ZOI). The ZOI describes the full surface profile of all peaks and valleys, rather than just measuring a scratch width. The ZOI has been found to be at least twice the size of a standard width measurement; in some cases, considerably greater, indicating that at least half of the disturbed surface area would be neglected without this insight. The ZOI is used to calculate a more robust data set of volume measurements that can be used to computationally reconstruct a resultant profile for de tailed analysis. Documenting additional changes to various surface roughness par ameters also allows key material attributes of importance to ultimate design applications to be quantified, such as depth of penetration and final abraded surface roughness. Further - more, by investigating the use of custom scratch tips for specific needs, the usefulness of having an abrasion metric that can measure the displaced volume in this standardized

  18. Abrasion and erosion testing of materials used in power production from coal

    SciTech Connect

    Tylczak, Joseph H.; Adler, Thomas A.; Rawers, James C.

    2003-09-01

    The Albany Research Center (ARC) has a long history of studying abrasive wear, related to mineral testing, handling, and processing. The center has also been instrumental in the design and development of wear test procedures and equipment. Research capabilities at ARC include Pin-on-Drum, Pin-on-Disk, and Dry Sand/Rubber Wheel abrasion tests, Jaw Crusher gouging test, Ball-on-Ball Impact test, and Jet erosion tests. Abrasive and erosive wear studies have been used to develop both new alloys and improved heat treatments of commercial alloys. As part of ARC’s newest iteration on wear testing to evaluate materials for use in new and existing pulverized coal combustion and gasifier power systems, the ARC has designed and constructed a new High Temperature Hostile Atmosphere Erosion Wear Test (HAET). This new piece of test apparatus is designed for erosive particle velocities of 10-40 m/sec and temperatures from room temperature (23°C) to 800+°C, with special control over the gas atmosphere. A variable speed whirling arm design is used to vary the impact energy of the gravity fed erosive particles. The specimens are mounted at the edge of a disk and allow a full range of impingement angles to be selected. An electric furnace heats the specimens in an enclosed retort to the selected temperature. Tests include both oxidizing conditions and reducing conditions. A range of gases, including CO, CO2, CH4, H2, H2S, HCl, N2, O2, and SO2 can be mixed and delivered to the retort. During the erosion testing a stream of abrasive powder is delivered in front of the specimens. This apparatus is designed to use low abrasive fluxes, which simulate real operating conditions in commercial power plants. Currently ~270 μm SiO2 particles are being used to simulate the abrasive impurities typically found in coal. Since operators are always striving for longer lifetimes and higher operating temperatures, this apparatus can help elucidate mechanisms of wastage and identify superior

  19. Tool wear of a single-crystal diamond tool in nano-groove machining of a quartz glass plate

    NASA Astrophysics Data System (ADS)

    Yoshino, Masahiko; Nakajima, Satoshi; Terano, Motoki

    2015-12-01

    Tool wear characteristics of a diamond tool in ductile mode machining are presented in this paper. Nano-groove machining of a quartz glass plate was conducted to examine the tool wear rate of a single-crystal diamond tool. Effects of lubrication on the tool wear rate were also evaluated. A numerical simulation technique was developed to evaluate the tool temperature and normal stress acting on the wear surface. From the simulation results it was found that the tool temperature does not increase during the machining experiment. It is also demonstrated that tool wear is attributed to the abrasive wear mechanism, but the effect of the adhesion wear mechanism is minor in nano-groove machining. It is found that the tool wear rate is reduced by using water or kerosene as a lubricant.

  20. Influence of air abrasion tips and operation modes on enamel-cutting characteristics

    PubMed Central

    Peruchi, Cláudia; Santos-Pinto, Ary; Dias, Tereza Cristina; Oliveira, Ana Carolina Mascarenhas; Santos-Pinto, Lourdes

    2013-01-01

    Objective: To assess the influence of air abrasion tips and system operation modes on enamel cutting. Methods: Forty bovine teeth were abraded with the air abrasion system Mach 4.1 for 10 and 15 seconds, employing conventional and sonic tips of 0.45-mm inner diameter and a 90° angle, and 27.5-μm aluminum oxide at 5.51 bar air pressure in continuous and pulsed modes. The width and depth of the resulting cuts were measured in SEM. Results: The multivariate analysis of variances revealed that, compared to the sonic tip, the conventional tip produced shallower cuts independent of the operation mode and the application period. Conclusions: The cutting patterns observed in this study suggest that the pulsed mode produced deeper cuts when both the conventional and sonic tips were used, and that the sonic tip cut more dental tissue than the conventional one. PMID:23408157

  1. M"ossbauer study of corrosion and abrasion products in oil transporting pipes

    NASA Astrophysics Data System (ADS)

    Gomez, Raul W.; Perez Mazariego, Jose Luis; Marquina, Vivianne; Marquina, Ma. Luisa; Ridaura, Rosalia; Martinez, Lorenzo

    2012-02-01

    It is known that one of the main technological problems in carbon steel oleoducts is the corrosion produced by different substances, such as water, carbon dioxide, sulfur, and microorganisms. In addition, if in such mixture there is sand, aggressive sludge can be form that abrasions material from the oleoduct. A room temperature M"ossbauer study of corroded material taken from different sites of oleoducts is presented. Most of the M"ossbauer spectra reveal the presence of nanoparticles, indicating that in these pipes the abrasion problem is severe. A preliminary identification of the oxidized samples suggests the presence of magnetite, and some Iron hydroxides. Further studies are in course in order to identify unambiguously the products present in the corroded materials.

  2. An experimental modeling and acoustic emission monitoring of abrasive wear in a steel/diabase pair

    NASA Astrophysics Data System (ADS)

    Korchuganov, M. A.; Filippov, A. V.; Tarasov, S. Yu.; Podgornyh, O. A.; Shamarin, N. N.; Filippova, E. O.

    2016-11-01

    The earthmoving of permafrost soil is a critical task for excavation of minerals and construction on new territories. Failure by abrasive wear is the main reason for excavation parts of earthmoving and soil cutting machines. Therefore investigation of this type of wear is a challenge for developing efficient and wear resistant working parts. This paper is focused on conducting tribological experiments with sliding the steel samples over the surface of diabase stone sample where abrasive wear conditions of soil cutting are modeled experimentally. The worn surfaces of all samples have been examined and transfer of metal and stone particles revealed. The acoustic emission (AE) signals have been recorded and related to the results of worn surface analysis. he acoustic emission (AE) signals have been recorded and related to the results of worn surface analysis. As shown the wear intensity correlates to that of acoustic emission. Both acoustic emission signal median frequency and energy are found to be sensitive to the wear mode.

  3. Self-healing of the superhydrophobicity by ironing for the abrasion durable superhydrophobic cotton fabrics

    PubMed Central

    Wu, Jingxia; Li, Jingye; Deng, Bo; Jiang, Haiqing; Wang, Ziqiang; Yu, Ming; Li, Linfan; Xing, Chenyang; Li, Yongjin

    2013-01-01

    Self-healing of the superhydrophobic cotton fabric (SCF) obtained by the radiation-induced graft polymerization of lauryl methacrylate (LMA) and n-hexyl methacrylate (HMA), can be achieved by ironing. Through the steam ironing process, the superhydrophobicity of the SCFs will be regenerated even after the yarns are ruptured during the abrasion test under a load pressure of 44.8 kPa. SCFs made from LMA grafted cotton fabric can ultimately withstand at least 24,000 cycles of abrasion with periodic steam ironing. The FT-IR microscope results show that the migration of the polymethacrylates graft chains from the interior to the surface is responsible for the self-healing effect. PMID:24135813

  4. Erosion and abrasion on dental structures undergoing at-home bleaching

    PubMed Central

    Demarco, Flávio Fernando; Meireles, Sônia Saeger; Sarmento, Hugo Ramalho; Dantas, Raquel Venâncio Fernandes; Botero, Tatiana; Tarquinio, Sandra Beatriz Chaves

    2011-01-01

    This review investigates erosion and abrasion in dental structures undergoing at- home bleaching. Dental erosion is a multifactorial condition that may be idiopathic or caused by a known acid source. Some bleaching agents have a pH lower than the critical level, which can cause changes in the enamel mineral content. Investigations have shown that at-home tooth bleaching with low concentrations of hydrogen or carbamide peroxide have no significant damaging effects on enamel and dentin surface properties. Most studies where erosion was observed were in vitro. Even though the treatment may cause side effects like sensitivity and gingival irritation, these usually disappear at the end of treatment. Considering the literature reviewed, we conclude that tooth bleaching agents based on hydrogen or carbamide peroxide have no clinically significant influence on enamel/dentin mineral loss caused by erosion or abrasion. Furthermore, the treatment is tolerable and safe, and any adverse effects can be easily reversed and controlled. PMID:23674914

  5. Abrasion, erosion, and abfraction combined with linear enamel hypoplasia: a case report.

    PubMed

    Boston, D W; al-bargi, H; Bogert, M

    1999-10-01

    Linear enamel hypoplasia is a developmental disturbance of enamel resulting in clinically visible horizontal defects in enamel that are present on eruption of the tooth. Nondevelopmental lesions of the hard tissues of the tooth, including carious, abrasion, erosion, attrition, and abfraction lesions, require varying amounts of time after tooth eruption to develop. Because linear enamel hypoplasia lesions are present on eruption and are exposed to the factors responsible for abrasion, erosion, and abfraction, nondevelopmental lesions could occur within them in any combination. This report describes a patient with multiple teeth with linear enamel hypoplasia lesions containing nondevelopmental defects as well as nondevelopmental defects that occurred separately. Severe pain and a unique lesion morphology were associated with the linear enamel hypoplasia defects. Affected teeth were extracted because of advanced periodontitis and were sectioned to determine the nature of the enamel and dentin lesions.

  6. Relationship of cheek tooth abrasion to fluoride-induced permanent incisor lesions in livestock.

    PubMed

    Shupe, J L; Christofferson, P V; Olson, A E; Allred, E S; Hurst, R L

    1987-10-01

    Teeth from cattle, sheep, and horses that ingested various fluoride intakes and teeth from field studies of these species plus deer, elk, and bison were examined for abnormalities. Approximately 99,000 animals in 322 herds were examined for fluorosis. From field studies, 988 cattle of various ages and with different degrees of dental fluorosis were slaughtered and necropsied. The severity of fluoride-induced mottling, hypoplasia, and abnormal abrasion of paired permanent incisor teeth was correlated with abrasion of premolar and molar (cheek) teeth that form and mineralize at approximately the same age. Severe irregular wear of cheek teeth impaired mastication and resulted in poor utilization of feed and unthriftiness. Excessive amounts of fluoride during tooth formation and mineralization induce characteristic dental changes. Offspring from the fluoride-affected animals did not have discernible fluoride-induced lesions in the deciduous teeth.

  7. A study on practical use of underwater abrasive water jet cutting

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hitoshi; Demura, Kenji

    1993-09-01

    The practicality of underwater abrasive water jet cutting technology was studied in experiments. A study of abrasives in slurried form showed that optimum polymer concentration can be selected to suit underwater conditions. For the long-distance transport of slurry from the ocean surface to the ocean floor, a direct supply system by hose proved to be practical. This system takes advantage of the insolubility of the slurry in water due to a difference in specific gravity. For cutting thick steel plate at great ocean depths, a simulation with a pressurized container revealed the requirements for actual cutting. Confirmation of remote cutting operations will become the most important technology in field applications. Underwater sound vibration characteristics were found to change significantly in direct response to modifications in cutting conditions. This will be important basic data to develop an effective sensoring method.

  8. Correlating field and laboratory rates of particle abrasion, Rio Medio, Sangre de Cristo Mountains, New Mexico

    NASA Astrophysics Data System (ADS)

    Polito, P. J.; Sklar, L. S.

    2006-12-01

    River bed sediments commonly fine downstream due to a combination of particle abrasion, selective transport of finer grains, and fining of the local sediment supply from hillslopes and tributaries. Particle abrasion rates can be directly measured in the laboratory using tumbling barrels and annular flumes, however, scaling experimental particle abrasion rates to the field has proven difficult due to the confounding effects of selective transport and local supply variations. Here we attempt to correlate laboratory and field rates of particle abrasion in a field setting where these confounding effects can be controlled. The Rio Medio, which flows westward from the crest of the Sangre de Cristo Mountains in north central New Mexico, is one of several streams studied by John P. Miller in the early 1960's. Several kilometers downstream of its headwaters, the river crosses the Picuris-Pecos fault. Upstream of the fault the river receives quartzite, sandstone and shale clasts from the Ortega Formation, while downstream sediments are supplied by the Embudo Granite. Because the upstream lithologies are not resupplied downstream of the fault, any observed fining of these clasts should be due only to abrasion and selective transport. We hypothesize that we can account for the effects of selective transport by comparing relative fining rates for the different upstream lithologies from both the field and a laboratory tumbler. By correlating laboratory abrasion rates with rock strength, we can predict the relative fining rates due solely to abrasion expected in the field; differences between the predicted and observed fining rates could then be attributed to selective transport. We used point counts to measure bed surface sediment grain size distributions at 15 locations along a 25 kilometer reach of the Rio Medio, beginning just downstream of the fault and ending upstream of a developed area with disturbed channel conditions. We recorded intermediate particle diameter as well

  9. [Effect of abrasion on three types of sutures in a metallic anchor].

    PubMed

    Acosta Rodríguez, Eduardo; Almazán Díaz, Arturo

    2007-01-01

    It is necessary to slide the suture into the articulation in the arthroscopic techniques, this produce friction and abrasion of the suture, this is the principal cause of failure in the union of anchor-suture. We used a Fastak 2.4 anchor, Sawbones, No 2 Ethibond, No 2 Fiberwire and No 2 Herculine. Each suture was introduce to the anchor eyelet and was cycled in four times with 40N. The angles of traction were 0 degrees and 45 degrees at the same direction of the anchor eyelet and 45 degrees with different direction of the anchor eyelet. Five sutures were used in every test. We performed the Kolmogorov-Smirnof and "t" Student tests. In all the tests there were a significant differences. The strength of the suture is affected by the abrasion in the anchor eyelet.

  10. A Study on 3-Body Abrasive Wear Behaviour of Aluminium 8011 / Graphite Metal Matrix Composite

    NASA Astrophysics Data System (ADS)

    Latha Shankar, B.; Anil, K. C.; Patil, Rahul

    2016-09-01

    Metals and alloys have found their vital role in many applications like structural, corrosive, tribological, etc., in engineering environment. The alloys/composites having high strength to low weight ratio have gained attention of many researchers recently. In this work, graphite reinforced Aluminium 8011 metal matrix composite was prepared by conventional stir casting route, by varying the weight % of reinforcement. Uniform distribution of Graphite in matrix alloy was confirmed by optical micrographs. Prepared composite specimens were subjected to 3-body abrasive testing by varying applied load and time, the silica particles of 400 grit size were used as abrasive particles. It was observed that with the increase of weight% of Graphite the wear resistance of composite was also increasing and on comparison it was found that reinforced composite gives good wear resistance than base alloy.

  11. Process for producing a well-adhered durable optical coating on an optical plastic substrate. [abrasion resistant polymethyl methacrylate lenses

    NASA Technical Reports Server (NTRS)

    Kubacki, R. M. (Inventor)

    1978-01-01

    A low temperature plasma polymerization process is described for applying an optical plastic substrate, such as a polymethyl methacrylate lens, with a single layer abrasive resistant coating to improve the durability of the plastic.

  12. Two-body, dry abrasive wear of Fe/Cr/C experimental alloys - relationship between microstructure and mechanical properties

    SciTech Connect

    Kwok, C.K.S.

    1982-01-01

    A systematic study of abrasive wear resistance of Fe/Cr/Mn based alloys has been carried out using a two body pin-on-disc wear machine. Abrasives used were silicon carbide, alumina and quartz. The objective of this study was to evaluate the abrasive wear resistance and to investigate the relationships between microstructure, mechanical properties, and abrasive wear resistance for these experimental alloys. Several commercial alloys were also tested to provide a basis for comparison. The goal of this study was to develop information so as to improve wear resistance of these experimental alloys by means of thermal treatments. Grain-refinement by double heat treatment was carried out in this research.

  13. Abrasive Wear of Four Direct Restorative Materials by Standard and Whitening Dentifrices

    DTIC Science & Technology

    2013-06-01

    creating cervical lesions and altering tooth surface is an area of interest in the dental community . This has led to the development of a number of...study of root caries : baseline and incidenc data. Journal of Dental Restorations, 64(9), 1141-1144. Barnes, D., Blank, L., Gingell, J., & Gilner, P... Community Dental Oral Epidemiology, 7(1), 57-64. Bull, W. H., Callender, R. M., Pugh, B. R., & Wood, G. D. (1968). The abrasion and cleaning

  14. Abrasive stripping square-wave voltammetry of blackberry, raspberry, strawberry, pomegranate, and sweet and blue potatoes.

    PubMed

    Komorsky-Lovrić, Šebojka; Novak, Ivana

    2011-08-01

    Electro-oxidation potentials of 7 fruits and vegetables were determined by abrasive stripping voltammetry. The responses were characterized by 2 peaks with maxima at 0.45 and 0.55 V compared with Ag/AgCl, respectively. Both electrode reactions appear reversible at a frequency of 8 Hz. They can be ascribed to anthocyanidins and ellagic acid as electroactive compounds. By this method, an antioxidative capacity of a certain plant can be quickly estimated without extraction of active components.

  15. Validation of Proposed Metrics for Two-Body Abrasion Scratch Test Analysis Standards

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    The objective of this work was to evaluate a set of standardized metrics proposed for characterizing a surface that has been scratched from a two-body abrasion test. This is achieved by defining a new abrasion region termed Zone of Interaction (ZOI). The ZOI describes the full surface profile of all peaks and valleys, rather than just measuring a scratch width as currently defined by the ASTM G 171 Standard. The ZOI has been found to be at least twice the size of a standard width measurement, in some cases considerably greater, indicating that at least half of the disturbed surface area would be neglected without this insight. The ZOI is used to calculate a more robust data set of volume measurements that can be used to computationally reconstruct a resultant profile for detailed analysis. Documenting additional changes to various surface roughness parameters also allows key material attributes of importance to ultimate design applications to be quantified, such as depth of penetration and final abraded surface roughness. Data are presented to show that different combinations of scratch tips and abraded materials can actually yield the same scratch width, but result in different volume displacement or removal measurements and therefore, the ZOI method is more discriminating than the ASTM method scratch width. Furthermore, by investigating the use of custom scratch tips for our specific needs, the usefulness of having an abrasion metric that can measure the displaced volume in this standardized manner, and not just by scratch width alone, is reinforced. This benefit is made apparent when a tip creates an intricate contour having multiple peaks and valleys within a single scratch. This work lays the foundation for updating scratch measurement standards to improve modeling and characterization of three-body abrasion test results.

  16. Development of intermetallic-hardened abrasion-resistant weld hardfacing alloys

    SciTech Connect

    School, M.R.

    1986-01-01

    Chromium and cobalt are strategic materials in the US and both are major constituents in many weld hardfacing alloys. Substitution for these materials or alternatives to their use was a primary direction of this investigation which was conducted in conjunction with the US Bureau of Mines. Minimization of the use of strategic materials was the criteria guiding the development of intermetallic-hardened abrasion resistant weld hardfacing materials. Other criteria were that the new alloy contain a hard intermetallic compound in an FCC matrix, and that these intermetallic compounds be stable at room temperature. A survey of ternary systems was made and the Fe-Mo-Ni system was selected to provide a basis for alloy development. Fe-Mo-Ni alloys synthesized by arc-melting and similar alloys made by welding possessed similar microstructures, a (Fe, Ni){sub 7}Mo{sub 6} intermetallic plus austenite eutectic in an austenitic matrix. These materials exhibited poor abrasive resistance. Silicon additions to the alloy promoted formation of a Laves phase FeMoSi intermetallic which helped increase the abrasive wear resistance. Through a series of alloy chemistry iterations a final composition of Fe-20Mo-15Ni-5Si was selected. Heat treatment of this alloy at 550 to 650 C caused second phase precipitation in the matrix and raised the hardness about 14 points HRC to 50 HRC. The alloy's wear rate, measured with the pin-on-drum abrasive wear test, was 6.3 to 6.5 mg/m. However this was twice the wear rate observed in commercial high-carbon high-chromium alloys. Based on examination of the alloy microstructures, their chemistry, and an analysis of the Fe-Mo-Si phase system; directions for further research are to increase the molybdenum and silicon content to produce a Fe-20Mo-10Ni-15Si composition.

  17. Heat sealable, flame and abrasion resistant coated fabric. [clothing and containers for space exploration

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    Flame retardant, abrasion resistant elastomeric compositions 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. Coated fabrics employing such elastomeric compositions as coating film are flexible, lightweight, and air impermeable and can be made using heat or dielectric sealing procedures.

  18. Shear bond strength of enamel surface treated with air-abrasive system.

    PubMed

    Borsatto, Maria Cristina; Catirse, Alma Blásida Elisaur Benitez; Palma Dibb, Regina Guenka; Nascimento, Telma Nunes do; Rocha, Renata Andréa Salvitti de Sá; Corona, Silmara Aparecida Milori

    2002-01-01

    The aim of this study was to evaluate the shear bond strength of a composite resin to dental enamel, using three different surface treatments. Fifteen sound third molars were randomly assigned to three groups. The mesial and distal surfaces were flattened and covered using adhesive tape with a central orifice delimiting the adhesion area (7.07 mm2). Group I, the enamel surface was conditioned with 37% phosphoric acid for 15 s; group II, the surface was treated using air abrasion with aluminum oxide; group III, the enamel surface was treated using an association of air abrasion with aluminum oxide and 37% phosphoric acid. The Single Bond (3M) adhesive system was applied and a Teflon matrix was placed and filled with composite resin Z-100 (3M) and light-cured. The shear bond strength test was performed with a universal testing machine. The acid etching technique and air abrasion with aluminum oxide associated with acid etching had the highest shear bond strength values. Data were subjected to statistical analysis using ANOVA and the Turkey test, and no statistically significant difference in shear bond strength was observed between group I (12.49 +/- 2.85 MPa) and group III (12.59 +/- 2.68 MPa). In contrast, both groups had statistically better shear bond strengths compared to group II (0.29 +/- 0.56 MPa; p < 0.05). Air abrasion with aluminum oxide does not substitute acid etching. The association of these methods to obtain adequate adhesion to the substrate is necessary.

  19. Effects of an Air-Powder Abrasive Device When Used during Periodontal Flap Surgery in Dogs.

    DTIC Science & Technology

    1983-01-01

    some of the effects of an air- powder abrasive system when used during periodontal flap surgery in dogs. In the first part of the study, periodontal...Histologically, signi- ficantly less inflammation was found on the experimental side at four days. In the second part of the study, the possible localized...apparent histologically in all the dogs through day seven. The third part of the study examined the possible damage which might occur if a periodontal flap

  20. Defining an Abrasion Index for Lunar Surface Systems as a Function of Dust Interaction Modes and Variable Concentration Zones

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    Unexpected issues were encountered during the Apollo era of lunar exploration due to detrimental abrasion of materials upon exposure to the fine-grained, irregular shaped dust on the surface of the Moon. For critical design features involving contact with the lunar surface and for astronaut safety concerns, operational concepts and dust tolerance must be considered in the early phases of mission planning. To systematically define material selection criteria, dust interaction can be characterized by two-body or three-body abrasion testing, and subcategorically by physical interactions of compression, rolling, sliding and bending representing specific applications within the system. Two-body abrasion occurs when a single particle or asperity slides across a given surface removing or displacing material. Three-body abrasion occurs when multiple particles interact with a solid surface, or in between two surfaces, allowing the abrasives to freely rotate and interact with the material(s), leading to removal or displacement of mass. Different modes of interaction are described in this paper along with corresponding types of tests that can be utilized to evaluate each configuration. In addition to differential modes of abrasion, variable concentrations of dust in different zones can also be considered for a given system design and operational protocol. These zones include: (1) outside the habitat where extensive dust exposure occurs, (2) in a transitional zone such as an airlock or suitport, and (3) inside the habitat or spacesuit with a low particle count. These zones can be used to help define dust interaction frequencies, and corresponding risks to the systems and/or crew can be addressed by appropriate mitigation strategies. An abrasion index is introduced that includes the level of risk, R, the hardness of the mineralogy, H, the severity of the abrasion mode, S, and the frequency of particle interactions, F.

  1. Adhesion of a self-etching system to dental substrate prepared by Er:YAG laser or air abrasion.

    PubMed

    Souza-Zaroni, Wanessa C; Chinelatti, Michelle A; Delfino, Carina S; Pécora, Jesus D; Palma-Dibb, Regina G; Corona, Silmara A M

    2008-08-01

    The purpose of this study was to assess the microtensile bond strength of a self-etching adhesive system to enamel and dentin prepared by Er:YAG laser irradiation or air abrasion, as well as to evaluate the adhesive interfaces by scanning electron microscopy (SEM). For microtensile bond strength test, 80 third molars were randomly assigned to five groups: Group I, carbide bur, control (CB); II, air abrasion with standard tip (ST); III, air abrasion with supersonic tip (SP); IV, Er:YAG laser 250 mJ/4 Hz (L250); V, Er:YAG laser 300 mJ/4 Hz (L300). Each group was divided into two subgroups (n = 8) (enamel, E and dentin, D). E and D surfaces were treated with the self-etching system Adper Prompt L-Pop and composite buildups were done with Filtek Z-250. Sticks with a cross-sectional area of 0.8 mm(2) (+/-0.2 mm(2)) were obtained and the bond strength tests were performed. Data were submitted to ANOVA and Tukey's test. For morphological analysis, disks of 30 third molars were restored, sectioned and prepared for SEM. Dentin presented the highest values of adhesion, differing from enamel. Laser and air-abrasion preparations were similar to enamel. Dentin air-abrasion with standard tip group showed higher bond strength results than Er:YAG-laser groups, however, air-abrasion and Er:YAG laser groups were similar to control group. SEM micrographs revealed that, for both enamel and dentin, the air-abrasion and laser preparations presented irregular adhesive interfaces, different from the ones prepared by rotary instrument. It was concluded that cavity preparations accomplished by both Er:YAG laser energies and air abrasion tips did not positively influence the adhesion to enamel and dentin.

  2. Susceptibility of acid-softened enamel to mechanical wear--ultrasonication versus toothbrushing abrasion.

    PubMed

    Wiegand, A; Wegehaupt, F; Werner, C; Attin, T

    2007-01-01

    The study aimed to compare the amounts of softened enamel removable by ultrasonication and by toothbrushing abrasion of briefly eroded samples. Thirty bovine enamel samples were demineralized in hydrochloric acid (pH 2.1) for 60 s and were then either brushed with 350 brushing strokes in toothpaste slurry (group A) or distilled water (group B) or were ultrasonicated for 120 s (group C). Enamel loss was measured after 10, 20, 50 and then after every 50 brushing strokes or after 5, 30, 60 and 120 s ultrasonication. Samples were indented with a Knoop diamond after erosion, and enamel loss due to abrasion or wear was calculated from the change in indentation depth after mechanical treatment. Within- and between-group comparisons were performed by ANOVA or t test. Initially, enamel loss increased with increasing brushing treatment or ultrasonication time. Enamel loss did not increase after 300 brushing strokes in group A (534 +/- 169 nm) or 250 brushing strokes in group B (423 +/- 80 nm), or after 60 s ultrasonication (231 +/- 72 nm). Enamel loss was significantly higher in groups A and B than in group C. The results confirm that ultrasonication removes only the outer, more highly demineralized part of the softened enamel layer. Results also indicate that toothbrushing abrasion removes more softened enamel from briefly eroded enamel than ultrasonication, and therefore probably removes partly demineralized enamel from the deeper part of the softened layer. In vivo, excessive toothbrushing might remove the softened enamel layer almost completely.

  3. Rock Cutting Depth Model Based on Kinetic Energy of Abrasive Waterjet

    NASA Astrophysics Data System (ADS)

    Oh, Tae-Min; Cho, Gye-Chun

    2016-03-01

    Abrasive waterjets are widely used in the fields of civil and mechanical engineering for cutting a great variety of hard materials including rocks, metals, and other materials. Cutting depth is an important index to estimate operating time and cost, but it is very difficult to predict because there are a number of influential variables (e.g., energy, geometry, material, and nozzle system parameters). In this study, the cutting depth is correlated to the maximum kinetic energy expressed in terms of energy (i.e., water pressure, water flow rate, abrasive feed rate, and traverse speed), geometry (i.e., standoff distance), material (i.e., α and β), and nozzle system parameters (i.e., nozzle size, shape, and jet diffusion level). The maximum kinetic energy cutting depth model is verified with experimental test data that are obtained using one type of hard granite specimen for various parameters. The results show a unique curve for a specific rock type in a power function between cutting depth and maximum kinetic energy. The cutting depth model developed here can be very useful for estimating the process time when cutting rock using an abrasive waterjet.

  4. 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.

  5. Microstructural effects in abrasive wear. Quarterly progress report, September 15-December 15, 1979

    SciTech Connect

    Fiore, N F; Kosel, T H; Channigiri, M; Desai, V; Fulcher, J

    1980-01-15

    This is the 11th quarterly report describing research aimed at establishing quantitative relations between microstructure and wear resistance of highly alloyed materials, including high-Cr white irons and experimental Co-base and Ni-base powder metallurgy (PM) alloys. The specific types of wear under study are low-stress abrasion and gouging wear encountered in mining, coal conversion and transfer applications. The white irons range in carbide volume fracton (v/sub f/) from 10 to 45%. They are of carefully balanced composition to produce maximum carbide hardness, v/sub f/ and matrix hardenability at minimum alloy content. Effort has been devoted to metallographic characterization of these alloys and to low-stress abrasion testing against dry SiO/sub 2/. Low-stress abrasion resistance passes through a maximum at intermediate v/sub f/, a finding which corroborates wet-sand, low-stress test results from another laboratory. Low- and high-matrix alloy content Co-base alloys are also under investigation. Both types of alloys have been processed by powder metallurgy (PM) to display a uniform array of fine, medium or coarse carbides in a FCC matrix. Extensive effort has been expended to develop metallographic procedures for characterizing the microstructures of the alloys. Of particular significance is the development of a one-step electrolytic etching-staining procedure which reveals matrix, matrix grain boundaries and carbides simultaneously in high contrast.

  6. Improved Soft Abrasive Flow Finishing Method Based on Turbulent Kinetic Energy Enhancing

    NASA Astrophysics Data System (ADS)

    LI, Jun; JI, Shiming; TAN, Dapeng

    2017-03-01

    Soft abrasive flow(SAF) finishing can process the irregular geometric surfaces, but with the matter of low processing efficiency. To address the issue, an improved SAF finishing method based on turbulent kinetic energy enhancing is proposed. A constrained flow passage with serration cross-section is constructed to increase the turbulence intensity. Taking the constrained flow passage as the objective, a two-phase fluid dynamic model is set up by using particle trajectory model and standard k-ɛ turbulence model, and the flow field characteristics of the flow passage are acquired. The numerical results show that the serration flow passage can enhance the turbulence intensity, uniform the particles distribution, and increase the particle concentration near the bottom wall. The observation results by particle image velocimetry(PIV) show that the internal vortex structures are formed in flow passage, and the abrasive flow takes on turbulence concentrating phenomenon in near-wall region. The finishing experiments prove that the proposed method can obtain better surface uniformity, and the processing efficiency can be improved more 35%. This research provides an abrasive flow modeling method to reveal the particle motion regulars, and can offer references to the technical optimization of fluid-based precision processing.

  7. The surface quality of AWJ cut parts as a function of abrasive material reusing rate

    NASA Astrophysics Data System (ADS)

    Schnakovszky, C.; Herghelegiu, E.; Radu, M. C.; Tampu, N. C.

    2015-11-01

    Abrasive water jet cutting (AWJ) has been extensively used during the last years to process a large variety of materials since it offers important advantages as a good quality of the processed surface, without heat affected zones, low environmental impact (no emission of dust or other compounds that endanger the health of the user), small induced mechanical stresses etc. The main disadvantage is the high cost of processing (cost of equipment and consumables). In view of this, the effects of reusing the abrasive material on the quality of processed surface are investigated in this paper. Two steel materials were used: OL 37 (S 235) with large applicability in machine building industry and 2P armor steel used in the arms industry. The reusing rate of the garnet abrasive material was: 0%, 20%, 40%, 60%, 80% and 100%. The quality of processed surface was quantified by the following parameters: width at the jet inlet (Li), width at the jet outlet (Lo), inclination angle (α), deviation from perpendicularity (u) and roughness (Ra).

  8. Nuclear-chemical methods in a hard tooth tissue abrasion study

    NASA Astrophysics Data System (ADS)

    Gosman, A.; Spěváček, V.; Koníček, J.; Vopálka, D.; Houŝová, D.; Doležalová, L.

    1999-01-01

    The advanced method consists in implantation—labelling of the thin surface layers of the solid objects, e.g. hard tooth tissue, by atoms of suitable natural or artificial radionuclides. Nuclides from the uranium series were implanted into the surface by using nuclear recoil effect at alpha decay of 226Ra to 222Rn, alpha decay of 222Rn to RaA, alpha decay of RaA to RaB (beta-emitter) and further alpha or beta emitters. With regard to chosen alpha detection and to the half—lives of the radionuclides, there was actually measured the activity of 222Rn, RaA and RaC’ in the thin surface layer. This was followed by the laboratory simulation of the abrasion in the system of “toothbrush—various suspensions of the tooth-pastes—hard tooth tissue (or material standard—ivory)” in specially designed device—the dentoabrasionmeter. The activities of the tissue surface measured before and after abrasion were used for calculations of the relative drop of the surface activity. On this basis the influence of various tooth-pastes containing various abrasive substances was determined.

  9. Influence of air abrasion preparation on microleakage in glass ionomer cement restorations.

    PubMed

    Reis, Lucia da Silva; Chinelatti, Michelle A; Corona, Silmara A M; Palma-Dibb, Regina G; Borsatto, Maria Cristina

    2004-11-01

    The aim of this study was to assess microleakage in class V cavities prepared by air abrasion or high-speed dental bur and restored with different glass ionomer cements. Sixty bovine incisors were equally divided into 6 groups: I, II and III (preparation by high-speed) and IV, V and VI (preparation by air abrasion). Groups I and IV were restored with Fuji IX; groups II and V with Ketac Molar; and groups III and VI with Vitremer. After 24 h (37 degrees C), specimens were thermocycled, isolated with nail varnish, immersed in a 0.2% Rhodamine B solution for 24 hours, sectioned longitudinally and analyzed for microleakage using an optical microscope connected to a digital camera and a computer. The images were digitized and a software allowed the quantitative evaluation of microleakage in millimeters. Data were analyzed by Wilcoxon and Kruskal-Wallis tests. It was observed that there were significant differences (p < 0.05) between incisal (enamel) and cervical (dentine/cementum) margins, mainly for Ketac Molar; there was no difference (p > 0.05) between preparation methods, except for group II (high-speed/Ketac Molar) that showed higher infiltration; regarding the materials, Ketac Molar demonstrated the highest microleakage values (p < 0.05), and only Vitremer sealed completely both margins of restorations. It was concluded that air abrasion preparation did not influence microleakage in class V restorations with the employed glass ionomer cements.

  10. Development and Testing of Abrasion Resistant Hard Coats For Polymer Film Reflectors: Preprint

    SciTech Connect

    Jorgensen, G.; Gee, R.; DiGrazia, M.

    2010-10-01

    Reflective polymer film technology can significantly reduce the cost of solar reflectors and installed Concentrated Solar Power (CSP) plants by both reduced material cost and lower weight. One challenge of polymer reflectors in the CSP environment pertains to contact cleaning methods typically used with glass mirrors. Such contact cleaning methods can scratch the surface of polymer reflectors and thereby reduce specular reflectance. ReflecTech, Inc. (a subsidiary of SkyFuel, Inc.) and the National Renewable Energy Laboratory (NREL) initiated a cooperative research and development agreement (CRADA) to devise and develop an abrasion resistant coating (ARC) suitable for deposition onto polymer based mirror film. A number of candidate ARC products were identified as candidate formulations. Industrial collaborators prepared samples having their ARCs deposited onto ReflecTech Mirror Film pre-laminated to aluminum sheet substrates. Samples were provided for evaluation and subjected to baseline (unweathered) and accelerated exposure conditions and subsequently characterized for abrasion resistance and adhesion. An advanced ARC product has been identified that exhibits outstanding initial abrasion resistance and adhesion to ReflecTech Mirror Film. These properties were also retained after exposure to the various accelerated stress conditions. This material has been successfully manufactured as a 1.5 m wide roll-to-roll construction in a production environment.

  11. Comparison of the mechanical effects of a toothbrush and standard abrasive on human and bovine dentine in vitro.

    PubMed

    Imfeld, T

    2001-01-01

    Dentine abrasion is an important possible side effect of individually used mechanical oral hygiene products. Since human teeth are sometimes not available in sufficient numbers for research purposes, bovine teeth are often used as a substitute for in vitro tests of dentine abrasion. The aim of the present comparative study was to determine the mechanical effects of a manual toothbrush and a standard abrasive on human and bovine dentine under standardized conditions. Roots of human and bovine teeth were radioactivated and subjected to standardized machine brushing using a manual toothbrush and a standard abrasive slurry. Dentine abrasion was assessed by measuring radioactive phosphorus contained in the slurry after brushing. Non-radioactive human and bovine roots were brushed in the same machine, and the generated surface roughness was assessed using profilometry. Artificially stained human and bovine roots were brushed as described, and the cleaning effect was expressed as the extent of stain-free surfaces after different brushing times. The results for abrasion and surface roughening found with bovine and human dentine suggest that if standardized methods are used, roots of bovine mandibular front teeth can be used in place of human roots for in vitro studies of the mechanical effects of toothbrushes and toothpastes on dentine. The use of bovine dentine for measuring the cleaning effects of these products is, however, not recommended.

  12. The Contribution of Abrasion and Size-Selective Sorting to Downstream Fining in a Tropical Montane Stream

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Quantifying the effect of abrasion vs. size-selective transport on downstream diminution of grain size and mass is a long-standing question in fluvial systems. While some authors have emphasized sorting by size-selective transport as the dominant fining mechanism in various rivers, others demonstrated the effectiveness of abrasion in certain fluvial systems. We present a synthetic grain-scale model in which we combine a recently developed geometric abrasion model (the so-called 'box equations' [1]) with a simplistic selective deposition rule. Box equations are capable to describe the evolution of both the shape and the size of the particles during abrasion, as opposed to previous models which only dealt with the size (or alternatively, the mass) diminution. We adapt our synthetic model to numerically simulate the downstream grain size and shape evolution in a short tropical river in Puerto Rico where we conducted a detailed field study. By switching off abrasion and selective deposition separately in the numerical model, the individual effects of these two processes can be examined. Based on our simplistic model we deduce that 1/3 of the mass of the grains may be lost only by abrasion in the examined river system. [1] Domokos, G., and G. W. Gibbons (2012), The evolution of pebble size and shape in space and time, Proc. R. Soc. A, 468(2146), 3059-3079, doi:10.1098/rspa.2011.0562.

  13. A blue-LED-based device for selective photocoagulation of superficial abrasions: theoretical modeling and in vivo validation

    NASA Astrophysics Data System (ADS)

    Rossi, Francesca; Pini, Roberto; De Siena, Gaetano; Massi, Daniela; Pavone, Francesco S.; Alfieri, Domenico; Cannarozzo, Giovanni

    2010-02-01

    The blue light (~400 nm) emitted by high power Light Emitting Diodes (LED) is selectively absorbed by the haemoglobin content of blood and then converted into heat. This is the basic concept in setting up a compact, low-cost, and easy-to-handle photohaemostasis device for the treatment of superficial skin abrasions. Its main application is in reducing bleeding from superficial capillary vessels during laser induced aesthetic treatments, such as skin resurfacing, thus reducing the treatment time and improving aesthetic results (reduction of scar formation). In this work we firstly present the preliminary modeling study: a Finite Element Model (FEM) of the LED induced photothermal process was set up, in order to estimate the optimal wavelength and treatment time, by studying the temperature dynamics in the tissue. Then, a compact, handheld illumination device has been designed: commercially available high power LEDs emitting in the blue region were mounted in a suitable and ergonomic case. The prototype was tested in the treatment of dorsal excoriations in rats. Thermal effects were monitored by an infrared thermocamera, experimentally evidencing the modest and confined heating effects and confirming the modeling predictions. Objective observations and histopathological analysis performed in a follow-up study showed no adverse reactions and no thermal damage in the treated areas and surrounding tissues. The device was then used in human patients, in order to stop bleeding during Erbium laser skin resurfacing procedure. By inducing LED-based photocoagulation, the overall treatment time was shortened and scar formation was reduced, thus enhancing esthetic effect of the laser procedure.

  14. Abrasions and lameness in piglets born in different farrowing systems with different types of floor

    PubMed Central

    Zoric, Mate; Nilsson, Ebba; Mattsson, Sigbrit; Lundeheim, Nils; Wallgren, Per

    2008-01-01

    Background The quality of the floor is essential to the welfare of piglets as abrasions often are recorded in newborn piglets, and such lesions may lead to lameness. Apart from animal suffering, lameness contributes to losses in form of dead piglets, decreased growth, and increased use of antibiotics and manual labour. Methods In a herd with three different farrowing systems, 37 litters (390 piglets) were studied until the age of 3 weeks with respect to presence of skin wounds and abrasions. Lameness was registered until the age of 7 weeks. Eight lame piglets were sacrificed before medical treatment and subjected to necropsy including histopathological and microbiological examinations. Isolates of streptococci, staphylococci and E. coli were tested with respect to antimicrobial resistance. Mastitis was observed in ten sows. Results The most severe abrasions at carpus and soles were seen in the system with a new solid concrete floor with a slatted floor over the dunging area. The lowest magnitude was observed in the deep litter system with peat. Sole bruising was more common in the systems with concrete floor compared to the deep litter system with peat, and the differce in prevalence was significant at all examination days. The lesions decreased with time and about 75% of the treatments for lameness were performed during the first three weeks of life. The overall prevalence of lameness was highest in the system with new solid concrete floor with a slatted floor over the dunging area (9.4%) followed by the old solid concrete floor (7.5%). A lower (p < 0.05) prevalence was seen in the deep litters system with peat (3.3%). No significant relationship between mastitis and abrasions or lameness in the offspring was observed. Conclusion There were large differences in the prevalence of abrasions and lameness between the floor types. The deep litter system with peat provided a soft and good floor for piglets. The overall prevalence of lameness was only diagnosed in every

  15. Minimal alterations on the enamel surface by micro-abrasion: in vitro roughness and wear assessments

    PubMed Central

    RODRIGUES, Marcela Charantola; MONDELLI, Rafael Francisco Lia; OLIVEIRA, Gabriela Ulian; FRANCO, Eduardo Batista; BASEGGIO, Wagner; WANG, Linda

    2013-01-01

    Objective: To evaluate the in vitro changes on the enamel surface after a micro-abrasion treatment promoted by different products. Material and Methods: Fifty (50) fragments of bovine enamel (15 mm x 5 mm) were randomly assigned to five groups (n=10) according to the product utilized: G1 (control)= silicone polisher (TDV), G2= 37% phosphoric acid (3M/ESPE) + pumice stone (SS White), G3= Micropol (DMC Equipment), G4= Opalustre (Ultradent) and G5= Whiteness RM (FGM Dental Products). Roughness and wear were the responsible variables used to analyze these surfaces in four stages: baseline, 60 s and 120 s after the micro-abrasion and after polishing, using a Hommel Tester T1000 device. After the tests, a normal distribution of data was verified, with repeated ANOVA analyses (p≤0.05) which were used to compare each product in different stages. One-way ANOVA and Tukey tests were applied for individual comparisons between the products in each stage (p≤0.05). Results: Means and standard deviations of roughness and wear (mm) after all the promoted stages were: G1=7.26(1.81)/13.16(2.67), G2=2.02(0.62)/37.44(3.33), G3=1.81(0.91)/34.93(6.92), G4=1.92(0.29)/38.42(0.65) and G5=1.98(0.53)/33.45(2.66). At 60 seconds, all products tended to produce less surface roughness with a variable gradual decrease over time. After polishing, there were no statistically significant differences between the groups, except for G1. Independent of the product utilized, the enamel wear occurred after the micro-abrasion. Conclusions: In this in vitro study, enamel micro-abrasion presented itself as a conservative approach, regardless of the type of the paste compound utilized. These products promoted minor roughness alterations and minimal wear. The use of phosphoric acid and pumice stone showed similar results to commercial products for the micro-abrasion with regard to the surface roughness and wear. PMID:23739863

  16. Rock Abrasion as Seen by the MSL Curiosity Rover: Insights on Physical Weathering on Mars

    NASA Astrophysics Data System (ADS)

    Bridges, N.; Day, M. D.; Le Mouelic, S.; Martin-Torres, F. J.; Newsom, H. E.; Sullivan, R. J., Jr.; Ullan, A.; Wiens, R. C.; Zorzano, M. P.

    2014-12-01

    Mars is a dry planet, with actively blowing sand in many regions. In the absence of stable liquid water and an active hydrosphere, rates of chemical weathering are slow, such that aeolian abrasion is a dominant agent of landscape modification where sand is present and winds above threshold occur at sufficient frequency. Reflecting this activity, ventifacts, rocks that have been abraded by windborne particles, and wind-eroded outcrops, are common. They provide invaluable markers of the Martian wind record and insight into climate and landscape modification. Ventifacts are distributed along the traverse of the Mars Science Laboratory Curiosity rover. They contain one or more diagnostic features and textures: Facets, keels, basal sills, elongated pits, scallops/flutes, grooves, rock tails, and lineations. Keels at the junction of facets are sharp enough to pose a hazard MSL's wheels in some areas. Geomorphic and textural patterns on outcrops indicate retreat of windward faces. Moonlight Valley and other depressions are demarcated by undercut walls and scree boulders, with the valley interiors containing fewer rocks, most of which show evidence for significant abrasion. Together, this suggests widening and undercutting of the valley walls, and erosion of interior rocks, by windblown sand. HiRISE images do not show any dark sand dunes in the traverse so far, in contrast to the large dune field to the south that is migrating up to 2 m per year. In addition, ChemCam shows that the rock Bathurst has a rind rich in mobile elements that would be removed in an abrading environment. This indicates that rock abrasion was likely more dominant in the past, a hypothesis consistent with rapid scarp retreat as suggested by the cosmogenic noble gases in Yellowknife Bay. Ventifacts and evidence for bedrock abrasion have also been found at the Pathfinder, Spirit, and Opportunity sites, areas, like the Curiosity traverse so far, that lack evidence for current high sand fluxes. Yardangs

  17. 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

  18. Evaluation of Beryllium, Total Chromium and Nickel in the Surface Contaminant Layer Available for Dermal Exposure After Abrasive Blasting in a Shipyard

    DTIC Science & Technology

    2013-04-24

    EVALUATION OF BERYLLIUM , TOTAL CHROMIUM AND NICKEL IN THE SURFACE CONTAMINANT LAYER AVAILABLE FOR DERMAL EXPOSURE AFTER ABRASIVE BLASTING IN A...34Evaluation of Levels of Beryllium , Total Chromium and Nickel in the Surface Contaminant Layer Available for Dermal Exposure after Abrasive Blasting in a...6772 ABSTRACT EVALUATION OF BERYLLIUM , TOTAL CHROMIUM AND NICKEL IN THE SURFACE CONTAMINANT LAYER AVAILABLE FOR DERMAL EXPOSURE AFTER ABRASIVE

  19. Ultrasonic energy as a tool to overcome some drawbacks in the determination of lead in brain tissue and urine of rats.

    PubMed

    Guimarães, D; Santos, J P; Carvalho, M L; Vale, G; Santos, H M; Geraldes, V; Rocha, I; Capelo, J L

    2011-10-30

    An ultrasonic assisted solid-liquid extraction method was developed to determine the level of lead in the brain and urine of rats. Lead was determined by electrothermal atomic absorption spectrometry with longitudinal-Zeeman background correction. Several analytical drawbacks were addressed and overcome, namely small brain sample mass and the formation of precipitate in the urine samples. Utrasonication provided by an ultrasonic probe succeeded in extracting lead from brain samples. Furthermore, it was demonstrated that the formation of a precipitate lowered the lead content in the liquid phase of the urine. Lead was back extracted from the precipitate to the liquid phase with the aid of ultrasonic energy and acidifying the urine with 10% v/v nitric acid. A microwave-assisted acid digestion protocol was used to check the completeness of the lead extraction. The within bath and between bath precision was 5% (n=9) and 7% (n=3) respectively. The limit of quantification was 1.05 μg g(-1) for brain samples and 2.1 μg L(-1) for urine samples. A total of 6 samples of urine and 12 samples of brain from control rats and another 6 samples of urine and 12 samples of brain from rats fed with tap water rich in lead acetate were used in this research. Lead levels in brain and urine from exposed rats ranged from 1.9 ± 0.2 μg g(-1) to 3.5 ± 0.2 μg g(-1) and from 752 ± 56 μg L(-1) to 60.9 ± 1.2 mg L(-1) respectively. Statistically significant differences of levels of lead in brain and urine were found between exposed and non exposed rats.

  20. Simplified Abrasion Test Methodology for Candidate EVA Glove Lay-Ups

    NASA Technical Reports Server (NTRS)

    Rabel, Emily; Aitchison, Lindsay

    2015-01-01

    During the Apollo Program, space suit outer-layer fabrics were badly abraded after performing just a few extravehicular activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots that penetrated the outer-layer fabric into the thermal protection layers after less than 8 hrs of surface operations. Current plans for the exploration planetary space suits require the space suits to support hundreds of hours of EVA on a lunar or Martian surface, creating a challenge for space suit designers to utilize materials advances made over the last 40 years and improve on the space suit fabrics used in the Apollo Program. Over the past 25 years the NASA Johnson Space Center Crew and Thermal Systems Division has focused on tumble testing as means of simulating wear on the outer layer of the space suit fabric. Most recently, in 2009, testing was performed on 4 different candidate outer layers to gather baseline data for future use in design of planetary space suit outer layers. In support of the High Performance EVA Glove Element of the Next Generation Life Support Project, testing a new configuration was recently attempted in which require 10% of the fabric per replicate of that need in 2009. The smaller fabric samples allowed for reduced per sample cost and flexibility to test small samples from manufacturers without the overhead to have a production run completed. Data collected from this iteration was compared to that taken in 2009 to validate the new test method. In addition the method also evaluated the fabrics and fabric layups used in a prototype thermal micrometeoroid garment (TMG) developed for EVA gloves under the NASA High Performance EVA Glove Project. This paper provides a review of previous abrasion studies on space suit fabrics, details methodologies used for abrasion testing in this particular study, results of the validation study, and results of the TMG testing.

  1. Effects of laser and acid etching and air abrasion on mineral content of dentin.

    PubMed

    Malkoc, Meral Arslan; Taşdemir, Serife Tuba; Ozturk, A Nilgun; Ozturk, Bora; Berk, Gizem

    2011-01-01

    The aim of this study was to evaluate the mineral content of dentin prepared using an Er,Cr:YSGG laser at four different power settings, acid etching, and air abrasion. The study teeth comprised 35 molars which were randomly divided into seven equal groups. The occlusal third of the crowns were cut with a slow-speed diamond saw. The groups were as follows: group A, control group; group B, dentin etched with 35% buffered phosphoric acid for 30 s; group C, dentin abraded at 60 psi with 50-µm aluminium oxide for 1 s; groups D-G, dentin irradiated with the Er,Cr:YSGG laser at 1.50 W (group D), 2.25 W (group E), 3.00 W (group F), and 3.50 W (group G). The levels of Mg, P, Ca, K and Na in each dentin slab were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Data were analysed by one way analysis of variance and Tukey HSD tests. There were no significant differences between the groups in the levels of Ca, P and Na, and the Ca/P ratio (p>0.05); however, there were significant differences in the levels of K (p<0.001) and Mg (p=0.13). In addition, the levels of Mg in the air abrasion group were higher than in the other groups (p<0.01). Etching with the Er,Cr:YSGG laser system, air abrasion and acid etching did not affect the levels of Ca, P and Na, or the Ca/P ratio, in the dentin surface.

  2. Erosion and abrasion-inhibiting in situ effect of the Euclea natalensis plant of African regions.

    PubMed

    Sales-Peres, Silvia Helena de Carvalho; Xavier, Cheila Nilza Hamina; Mapengo, Marta Artemisa Abel; Forim, Moacir Rossi; Silva, Maria de Fatima; Sales-Peres, Arsenio

    2016-06-14

    This study evaluated the effect of Euclea natalensis gel on the reduction of erosive wear with or without abrasion, in enamel and dentin. During two five-day experimental crossover phases, volunteers (n = 10) wore palatal devices containing human enamel and dentin blocks (E = 8 and D = 8). The gel was applied in a thin layer in the experimental group, and was not applied in the control group. In the intraoral phase, volunteers used the palatal appliance for 12 h before the gel treatment, and were instructed to start the erosive challenges 6 h after the gel application. Erosion was performed with Coca-Cola® (for 5 min) 4 times/day. The appliance was then put back into the mouth and was brushed after 30 minutes. After intraoral exposure, the appliances were removed and the specimens were analyzed using profilometry (mean ± SD, μm). The Euclea natalensis gel caused less wear in enamel in the experimental group (EROS = 12.86 ± 1.75 µm; EROS + ABRAS = 12.13 ± 2.12 µm) than in the control group (EROS = 14.12 ± 7.66 µm; EROS + ABRAS = 16.29 ± 10.72 µm); however, the groups did not differ from each other significantly. A statistically significant value was found for erosion and eros + abrasion in dentin (p = 0.001). Euclea natalensis may play a role in the prevention of dentin loss under mild erosive and abrasive conditions. A clinical trial is required to confirm these promising results in a clinical situation.

  3. 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

  4. Microleakage on Class V glass ionomer restorations after cavity preparation with aluminum oxide air abrasion.

    PubMed

    Corona, Silmara Aparecida Milori; Borsatto, Maria Cristina; Rocha, Renata Andréa Salvitti de Sá; Palma-Dibb, Regina Guenka

    2005-01-01

    This in vitro study assessed the marginal microleakage on class V cavities prepared with aluminum oxide air abrasion and restored with different glass ionomer cements. The cavities were prepared on the buccal and lingual surfaces of 15 sound third molars with an air- abrasion device (Kreativ Mach 4.1; New Image) using a 27.5-microm aluminum oxide particle stream, and were assigned to 3 groups of 10 cavities each. The restorative materials were: group I, a conventional glass ionomer cement (Ketac-Fil); groups II and III, resin-modified glass ionomer cements (Vitremer R and Fuji II LC, respectively). After placement of the restorations, the teeth were stored in distilled water at 37 degrees C for 24 h, polished and then submitted to a thermocycling regimen of 500 cycles, isolated, immersed in 0.2% Rhodamine B solution for 24 h, included and serially sectioned. Microleakage was assessed by viewing the specimens under an optical microscope connected to a color video camera and a computer. The images obtained were digitized and analyzed for microleakage using software that allows for a standard quantitative assessment of dye penetration in millimeters. Statistical analysis was done using the Kruskall-Wallis and Wilcoxon tests. Means of dye penetration (%) were: occlusal - I: 25.76 +/- 34.35, II: 20.00 +/- 42.16, III: 28.25 +/- 41.67; cervical - I: 23.72 +/- 41.84; II: 44.22 +/- 49.69, III: 39.27 +/- 50.74. No statistically significant differences (p>0.05) were observed among either the glass ionomer cements or the margins. In conclusion, class V cavities restored with either conventional or resin-modified glass ionomer cements after preparation with aluminum oxide air abrasion did not show complete sealing at the enamel and dentin/cementum margins.

  5. Preparation and characterization of poly(vinylidene fluoride)/nanoclay nanocomposite flat sheet membranes for abrasion resistance.

    PubMed

    Lai, Chi Yan; Groth, Andrew; Gray, Stephen; Duke, Mikel

    2014-06-15

    Membranes with more resilience to abrasive wear are highly desired in water treatment, especially for seawater desalination. Nanocomposite poly(vinylidene fluoride) (PVDF)/nanoclay membranes were prepared by phase inversion and then tested for abrasion resistance. Their material properties were characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), tensile testing, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Nanoclay Cloisite(®) 15A was utilised as the inorganic nanoparticle incorporated into PVDF. FTIR results showed a shifting of the PVDF crystalline phase from α to β thus indicating that the nanoclay altered the PVDF host material's structure and mechanical properties in terms of stiffness and toughness. Water permeation test showed that nanoclay at low concentration tended to reduce water flux. All nanocomposite membranes, with between 1 wt% and 5 wt% initial nanoclay loading, were more abrasion resistant than the control PVDF membrane. However, the 1 wt% exhibited superior resistance, lasting two times longer than the reference PVDF membrane under the same abrasive condition. The 1 wt% nanoclay membrane appeared less abraded by SEM observation, while also having the greatest tensile strength improvement (from 4.5 MPa to 4.9 MPa). This membrane also had the smallest agglomerated nanoclay particle size and highest toughness compared to the higher nanoclay content membranes. Nanoclays are therefore useful for improving abrasion resistance of PVDF membranes, but optimal loadings are essential to avoid losing essential mechanical properties.

  6. The effect of abrasive blasting on the strength of a joint between dental porcelain and metal base.

    PubMed

    Pietnicki, Krzysztof; Wołowiec, Emilia; Klimek, Leszek

    2014-01-01

    This paper presents the effect of selected parameters of abrasive blasting on the strength of a joint between dental porcelain and metal base. Experiments were conducted for different grain sizes of abrasive material and different blasting angles, with a constant blasting pressure. InLine dental porcelain was fused on samples of cobalt-chromium alloy following abrasive blasting; they were subsequently subjected to shearing forces on a testing machine. The fractures were observed under an electron scanning microscope in order to determine the character and course of fracturing. Strength tests showed that the grain size of abrasive material was a parameter with the greatest effect on the strength. The best effects were achieved for samples subjected to abrasive blasting with material with grain size of 110 μm. No statistically significant differences were found for the strength of samples worked at different angles. The results of the fractographic examinations have shown that in all the samples, fracturing occurred mainly along the porcelain-metal boundary, with few cases of fracturing through porcelain.

  7. Peel strength of denture liner to PMMA and polyamide: laser versus air-abrasion

    PubMed Central

    Bagis, Bora; Özcan, Mutlu; Durkan, Rukiye; Turgut, Sedanur; Ates, Sabit Melih

    2013-01-01

    PURPOSE This study investigated the effect of laser parameters and air-abrasion on the peel strength of silicon-based soft denture liner to different denture resins. MATERIALS AND METHODS Specimens (N=180) were prepared out of three different denture base resins (Rodex, cross-linked denture base acrylic resin; Paladent, heat-cured acrylic resin; Deflex, Polyamide resin) (75 mm × 25 mm × 3 mm). A silicon-based soft denture liner (Molloplast B) was applied to the denture resins after the following conditioning methods: a) Air-abrasion (50 µm), b) Er,Cr:YSGG laser (Waterlase MD Turbo, Biolase Technology) at 2 W-20 Hz, c) Er,Cr:YSGG laser at 2 W-30 Hz, d) Er,Cr:YSGG laser at 3 W-20 Hz, e) Er,Cr:YSGG laser at 3 W-30 Hz. Non-conditioned group acted as the control group. Peel test was performed in a universal testing machine. Failure modes were evaluated visually. Data were analyzed using two-way ANOVA and Tukey's test (α=.05). RESULTS Denture liner tested showed increased peel strength after laser treatment with different parameters (3.9±0.4 - 5.58±0.6 MPa) compared to the control (3.64±0.5 - 4.58±0.5 MPa) and air-abraded groups (3.1±0.6 - 4.46±0.3 MPa), but the results were not statistically significant except for Paladent, with the pretreatment of Er,Cr:YSGG laser at 3 W-20 Hz. Polyamide resin after air-abrasion showed significantly lower peel strength than those of other groups (3.1±0.6 MPa). CONCLUSION Heat-cured acrylic resin, PMMA, may benefit from Er,Cr:YSGG laser treatment at 3 W-20 Hz irradiation. Air-abrasion of polyamide resins should be avoided not to impair their peel bond strengths to silicon-based soft denture liners. PMID:24049570

  8. K/Na-treated Fe-Cr-C hardfacing alloys with high-impact-abrasion resistance

    SciTech Connect

    Yang, J.H.; Wang, X.B.

    1995-03-01

    This paper deals with K/Na-containing additives in the coatings or cores of electrodes, transforming the martensitic matrix of Fe-Cr-C hardfacing alloy into an austenitic one. The austenitic matrix hardened by the fine dispersed (Cr, Fe){sub 7}C{sub 3}, together with the isolated lumpish eutectic carbide, enhance both the impact and abrasion resistance of this alloy. The authors also found that Na doubled the effectiveness of the additive, and 50% less is needed to get better results compared to the K addition.

  9. An unusual case of tooth loss, abrasion, and erosion associated with a culturally accepted habit.

    PubMed

    Johnson, Cleverick D; Shynett, Betty; Dosch, Robert; Paulson, Robyn

    2007-01-01

    Tooth structure loss is a normal part of the aging process, with generalized predictable patterns. However, when a dentist is faced with an atypical pattern of extensive structural damage, identifying the etiology responsible for the catastrophic collapse of a patient's anterior incisal guidance can be a diagnostic challenge. Clinicians who are presented with plausible medical histories juxtaposed with socially and culturally accepted eating behaviors may clarify an otherwise nebulous clinical presentation. This article presents an unusual case report involving both synergistic and synchronous habitual and culturally adopted eating practices and pica, which resulted in severe tooth abrasion, abfraction, and erosion.

  10. The effect of daily fluoride mouth rinsing on enamel erosive/abrasive wear in situ.

    PubMed

    Stenhagen, K R; Hove, L H; Holme, B; Tveit, A B

    2013-01-01

    It is not known whether application of fluoride agents on enamel results in lasting resistance to erosive/abrasive wear. We investigated if one daily mouth rinse with sodium fluoride (NaF), stannous fluoride (SnF(2)) or titanium tetrafluoride (TiF(4)) solutions protected enamel against erosive/abrasive wear in situ (a paired, randomised and blind study). Sixteen molars were cut into 4 specimens, each with one amalgam filling (measurement reference surface). Two teeth (2 × 4 specimens) were mounted bilaterally (buccal aspects) on acrylic mandibular appliances and worn for 9 days by 8 volunteers. Every morning, the specimens were brushed manually with water (30 s) extra-orally. Then fluoride solutions (0.4% SnF(2) pH 2.5; 0.15% TiF(4) pH 2.1; 0.2% NaF pH 6.5, all 0.05 M F) were applied (2 min). Three of the specimens from each tooth got different treatment, and the fourth served as control. At midday, the specimens were etched for 2 min in 300 ml fresh 0.01 M hydrochloric acid and rinsed in tap water. This etch procedure was repeated in the afternoon. Topographic measurements were performed by a white-light interferometer. Mean surface loss (±SD) for 16 teeth after 9 days was: SnF(2) 1.8 ± 1.9 µm, TiF(4) 3.1 ± 4.8 µm, NaF 26.3 ± 4.7 µm, control 32.3 ± 4.4 µm. Daily rinse with SnF(2), TiF(4) and NaF resulted in 94, 90 and 18% reduction in enamel erosive/abrasive wear, respectively, compared with control (p < 0.05). The superior protective effect of daily rinse with either stannous or titanium tetrafluoride solutions on erosive/abrasive enamel wear is promising.

  11. Cut Front Geometry Characterization in Cutting Applications of Brass with Abrasive Water Jet

    NASA Astrophysics Data System (ADS)

    Akkurt, Adnan

    2010-06-01

    Abrasive water jet (AWJ) cutting is an advanced manufacturing process for machining hard to cut materials. In this study, brass-353 samples of different thicknesses were cut by AWJ using different feed rates to identify the relationships between depth of cut (material thickness), feed rate, and deflection of cutting edge geometry. The effects of material thickness on the AWJ cut surface roughness were investigated and discussed. Deflection of cutting edge geometry in AWJ cutting process was assessed. Cutting edge geometry was characterized by analyzing the surface properties of cut samples.

  12. 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.

  13. Effect of radiation cross-linking on the abrasive wear behaviour of polyethylenes

    NASA Astrophysics Data System (ADS)

    Gul, Rizwan M.; Khan, Tahir I.

    2014-06-01

    This study explores the differences in the dry abrasive wear behavior of different polyethylenes, and compares the effect of radiation cross-linking on the wear behavior. Four different types of polyethylenes: LDPE, LLDPE, HDPE and UHMWPE were studied. Cross-linking was carried out by high energy electron beam with radiation dose of 200 kGy. The results show that in unirradiated state UHMWPE has excellent wear resistance, with HDPE showing comparable wear properties; both LDPE and LLDPE exhibit high wear rate. Cross-linking improves wear rate of LDPE and UHMWPE, however, the wear rate of HDPE and LLDPE increases with cross-linking.

  14. Study of abrasive wear rate of silicon using n-alcohols

    NASA Technical Reports Server (NTRS)

    Danyluk, S.

    1982-01-01

    The work carried out at the University of Illinois at Chicago for the Flat-Plate Solar Array Project under contract No. 956053 is summarized. The abrasion wear rate of silicon in a number of fluid environments and the parameters that influence the surface mechanical properties of silicon were determined. Three tests were carried out in this study: circular and linear multiple-scratch test, microhardness test and a three-point bend test. The pertinent parameters such as effect of surface orientation, dopant and fluid properties were sorted. A brief review and critique of previous work is presented.

  15. 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.

  16. Corneal Abrasions

    MedlinePlus

    ... particles of wood, metal or other materials to fly into the air (such as a chainsaw or ... UsCopyright & PermissionsPrivacy PolicyContact FamilyDoctor.org is powered by © 2017 American Academy of Family Physicians

  17. Corneal Abrasions

    MedlinePlus

    ... help you take these steps: If you wear contact lenses, take them out. Rinse your eye with clean ... doctor may suggest pain medications. If you wear contact lenses, your doctor may tell you not to wear ...

  18. Air Abrasion

    MedlinePlus

    ... information you need from the Academy of General Dentistry Sunday, April 9, 2017 About | Contact InfoBites Quick ... general dentist, who has been trained in restorative dentistry techniques, will perform any procedures that use air- ...

  19. Zircon U-Pb Age Distributions in Cogenetic Crystal-Rich Dacitic and Crystal-Poor Rhyolitic Members of Zoned Ignimbrites in the Southern Rocky Mountains by Chemical Abrasion Inductively-Coupled-Plasma Mass Spectrometry (CA-LA-ICP-MS).

    NASA Astrophysics Data System (ADS)

    Sliwinski, J.; Zimmerer, M. J.; Guillong, M.; Bachmann, O.; Lipman, P. W.

    2015-12-01

    The San Juan locus of the Southern Rocky Mountain Volcanic Field (SRMVF) in SW Colorado represents an erosional remnant of a mid-Tertiary (~37-23 Ma) ignimbrite flare up that produced some of the most voluminous ignimbrites on Earth. A key feature of many SRMVF ignimbrites is compositional zonation, with many volcanic units comprising both dacitic and rhyolitic horizons. Geochemical, field and petrographic evidence suggests that dacites and rhyolites are cogenetic. Here, we report U-Pb zircon ages by chemical abrasion inductively-coupled-plasma mass spectrometry (CA-LA-ICPMS) for rhyolitic and dacitic components in four units: the Bonanza, Rat Creek, Carpenter Ridge and Nelson Mountain Tuffs. All units show zircon age spectra that are either within analytical uncertainty of Ar/Ar ages or are appreciably older, indicating prolonged magma residence times (~500 ka) prior to eruption. Anomalously young Pb-loss zones in zircon have been largely removed by chemical abrasion. Older, inherited zircons and zircon cores (60-2000 Ma) are rare in all samples, suggesting limited assimilation of upper crustal Precambrian country rock or complete resorption during recharge events and magma chamber growth.

  20. In vitro evaluation of abrasion of eroded enamel by different manual, power and sonic toothbrushes.

    PubMed

    Wiegand, A; Begic, M; Attin, T

    2006-01-01

    This study aimed to evaluate the susceptibility of eroded enamel to brushing abrasion performed by manual, power or sonic toothbrushes. Bovine enamel samples were subjected to 5 cycles, each consisting of 5 min demineralisation, 15 min remineralisation and 10 min brushing in a machine. Toothbrushing with the activated electric devices was supplemented with 20 linear strokes/min. Furthermore, enamel specimens were brushed with 20 linear strokes/min or 80 linear strokes/min with the electric toothbrushes without their individual operating action. A manual brush was applied at 100, 20 or 80 linear strokes/min. Specimens of the control group were not brushed after demineralisation. Loss of enamel was determined by profilometry. For all groups, substrate loss for linear brushing treatment applying 20 or 80 strokes/min did not differ significantly from the control (4.97 +/- 1.49 microm). Three power toothbrushing treatments significantly increased abrasion compared to linear brushing treatment with 20 or 80 strokes/min in their inactivated condition. The results indicate that brushing treatment with power or sonic toothbrushes may lead to significantly higher loss of demineralised enamel compared to toothbrushing without power or sonic support.

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

    PubMed

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

    2012-07-01

    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.

  2. Application of image stitching in rail abrasion 3D online detection

    NASA Astrophysics Data System (ADS)

    Lee, Jinlong; Gao, Xiaorong; Wang, Zeyong; Zhao, Quanke; Luo, Lin

    2016-09-01

    PMP (Phase measuring Profilometry) is an excellent 3D online measurement method for its high precision. However, the measuring range is limited. While the rail is so long that far exceeds the measuring limit, the image stitching should be used to extent it. In this paper, based on the improved Stoilov algorithm, the rail shape is three-dimensionally reconstructed and the abrasion is detected combines image stitching. Two types of schemes are researched: (1)image stitching is firstly used on the deformed fringe patterns and then a larger range rail is constructed with Stoilov algorithm; (2)the three-dimensional construction of two fringe pattern is firstly performed, and then the constructed images are stitched into longer rail. In this paper, the improved Stoilov algorithm based on statistical approach and stitching algorithm are analyzed. 3D Peaks function is simulated to verify the two methods, and then three-dimensional rail shape is recovered based on these two methods and the rail abrasion is measured with the relative precision of higher than 0.1%, which is much higher than traditional methods, such as linear laser scanning.

  3. Comparative study for surface topography of bone drilling using conventional drilling and loose abrasive machining.

    PubMed

    Singh, Gurmeet; Jain, Vivek; Gupta, Dheeraj

    2015-03-01

    Drilling through the bone is a complicated process in orthopaedic surgery. It involves human as a part of the work so it needs better perfection and quality which leads to the sustainability. Different studies were carried out on this curious topic and some interesting results were obtained, which help the orthopaedic surgeon on the operation table. Major problems faced during bone drilling were crack initiation, thermal necrosis and burr formation. The surface topography of the bone is an indirect indication for the sustainability of bone joint. In this study, a comparison is made between conventional and a loose abrasive unconventional drilling technique for the surface characterization of the bone. The attempt has been made to show the feasibility of bone drilling with non-conventional technique and its aftereffect on the bone structure. The burr formation during conventional bone drilling was found to be more which leads to problems such as crack initiation and thermal necrosis. Scanning electrode microscope and surface roughness tester were used to characterize the surface of the fine drilled bone specimen and the results testified quite better surface finish and least crack formation while drilling with loose abrasive unconventional technique.

  4. Hydro-abrasive erosion of hydraulic turbines caused by sediment - a century of research and development

    NASA Astrophysics Data System (ADS)

    Felix, D.; Albayrak, I.; Abgottspon, A.; Boes, R. M.

    2016-11-01

    Hydro-abrasive erosion of hydraulic turbines is an economically important issue due to maintenance costs and production losses, in particular at high- and medium-head run-of- river hydropower plants (HPPs) on sediment laden rivers. In this paper, research and development in this field over the last century are reviewed. Facilities for sediment exclusion, typically sand traps, as well as turbine design and materials have been improved considerably. Since the 1980s, hard-coatings have been applied on Francis and Pelton turbine parts of erosion-prone HPPs and became state-of-the-art. These measures have led to increased times between overhauls and smaller efficiency reductions. Analytical, laboratory and field investigations have contributed to a better processes understanding and quantification of sediment-related effects on turbines. More recently, progress has been made in numerical modelling of turbine erosion. To calibrate, validate and further develop prediction models, more measurements from both physical model tests in laboratories and real-scale data from HPPs are required. Significant improvements to mitigate hydro-abrasive erosion have been achieved so far and development is ongoing. A good collaboration between turbine manufacturers, HPP operators, measuring equipment suppliers, engineering consultants, and research institutes is required. This contributes to the energy- and cost-efficient use of the worldwide hydropower potential.

  5. Effects of enamel abrasion, salivary pellicle, and measurement angle on the optical assessment of dental erosion

    NASA Astrophysics Data System (ADS)

    Lussi, Adrian; Bossen, Anke; Höschele, Christoph; Beyeler, Barbara; Megert, Brigitte; Meier, Christoph; Rakhmatullina, Ekaterina

    2012-09-01

    The present study assessed the effects of abrasion, salivary proteins, and measurement angle on the quantification of early dental erosion by the analysis of reflection intensities from enamel. Enamel from 184 caries-free human molars was used for in vitro erosion in citric acid (pH 3.6). Abrasion of the eroded enamel resulted in a 6% to 14% increase in the specular reflection intensity compared to only eroded enamel, and the reflection increase depended on the erosion degree. Nevertheless, monitoring of early erosion by reflection analysis was possible even in the abraded eroded teeth. The presence of the salivary pellicle induced up to 22% higher reflection intensities due to the smoothing of the eroded enamel by the adhered proteins. However, this measurement artifact could be significantly minimized (p<0.05) by removing the pellicle layer with 3% NaOCl solution. Change of the measurement angles from 45 to 60 deg did not improve the sensitivity of the analysis at late erosion stages. The applicability of the method for monitoring the remineralization of eroded enamel remained unclear in a demineralization/remineralization cycling model of early dental erosion in vitro.

  6. ICAM-1 mediates surface contact between neutrophils and keratocytes following corneal epithelial abrasion in the mouse

    PubMed Central

    Gagen, Debjani; Laubinger, Sara; Li, Zhijie; Petrescu, Matei S.; Brown, Evelyn S.; Smith, C. Wayne; Burns, Alan R.

    2010-01-01

    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 PMN contact with stromal keratocytes is CD18-dependent, while contact with collagen is CD18-independent. In the present study, we wished to extend these observations and determine if ICAM-1, a known ligand for CD18, mediates PMN contact with keratocytes during corneal wound healing. Uninjured and injured right corneas from C57Bl/6 wild type (WT) mice and ICAM-1−/− mice were processed for transmission electron microscopy and imaged for morphometric analysis. PMN migration, stromal thickness, and ICAM-1 staining were evaluated using light microscopy. Twelve hours after epithelial abrasion, PMN surface contact with paralimbal keratocytes in ICAM-1−/− corneas was reduced to ~50% of that observed in WT corneas; PMN surface contact with collagen was not affected. Stromal thickness (edema), keratocyte network surface area and keratocyte shape were similar in ICAM-1−/− and WT corneas. WT keratocyte ICAM-1 expression was detected at baseline and ICAM-1 staining intensity increased following injury. Since ICAM-1 is readily detected on mouse keratocytes and PMN-keratocyte surface contact in ICAM-1−/− mice is markedly reduced, the data suggest PMN adhesive interactions with keratocyte stromal networks is in part regulated by keratocyte ICAM-1 expression. PMID:20713042

  7. 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.

  8. Analysis of silt abrasion of the impeller ring in a centrifugal pump with J-grooves

    NASA Astrophysics Data System (ADS)

    Qian, Z. D.; Wang, Z. Y.; Guo, Z. W.; Dong, J.; Lu, J.

    2016-05-01

    The water flow and movement of silt in a prototype double-suction centrifugal pump was simulated using an Euler-Lagrange multiphase flow model. J-Grooves were adopted to protect the impeller ring from silt abrasion. The influence of J-grooves on the silt concentration and pump efficiency was analyzed. The results show that the radial component of the relative velocity around the impeller ring is too low to move the silt out of the spacing between the impeller plate and the casing. The high silt concentration around the impeller ring is the major contributor to silt abrasion of the impeller ring. The J-grooves induce two strong vortices, which increase the radial component of the relative velocity of water and reduce the silt concentration around the impeller ring, but additional friction losses are introduced and the pump efficiency is decreased. Optimization of the number and shape of J-grooves decreases losses in the efficiency of the pump, and effectively protects the impeller ring. Case 4 was found the most effective configuration in this study.

  9. Technologies and experience with monitoring sediments for protecting turbines from abrasion

    NASA Astrophysics Data System (ADS)

    Agrawal, Y.; Slade, W.; Pottsmith, C.; Dana, D.

    2016-11-01

    Abrasion of turbines by sediments is a constant threat in high head and high sediment load situations. It is widely recognized that larger grains cause abrasion, although no consensus on a critical size exists. Grain hardness plays a second key role. Thus monitoring of sediment concentration is highly desirable, particularly with attention paid to the large grains. This has recently become possible with LISST instruments that use laser diffraction (LD) technology. These in-line instruments measure multi-angle laser light scattering, which is converted to a particle size distribution in a pre-defined size range. In order to reach high concentrations, the instruments incorporate auto-dilution capability. The data are transmitted to the control room. Provided software displays concentration history in up to 4 size classes, and the software is capable of generating alarms when sufficiently high concentrations occur. Since no definition exists for this sufficiently high concentration, in this paper we propose an objective criterion based on the rate of revenue generation contrasted with rate of cost of turbine repair. This simple idea helps guide the plant operator to set shut-down thresholds during sediment transport events. We also introduce a lower cost, high-frequency pulsed acoustic sensor for sediment monitoring. The rather lower accuracy of this device is offset by its lower cost that is suitable for small plants.

  10. Simulation of abrasive flow machining process for 2D and 3D mixture models

    NASA Astrophysics Data System (ADS)

    Dash, Rupalika; Maity, Kalipada

    2015-12-01

    Improvement of surface finish and material removal has been quite a challenge in a finishing operation such as abrasive flow machining (AFM). Factors that affect the surface finish and material removal are media viscosity, extrusion pressure, piston velocity, and particle size in abrasive flow machining process. Performing experiments for all the parameters and accurately obtaining an optimized parameter in a short time are difficult to accomplish because the operation requires a precise finish. Computational fluid dynamics (CFD) simulation was employed to accurately determine optimum parameters. In the current work, a 2D model was designed, and the flow analysis, force calculation, and material removal prediction were performed and compared with the available experimental data. Another 3D model for a swaging die finishing using AFM was simulated at different viscosities of the media to study the effects on the controlling parameters. A CFD simulation was performed by using commercially available ANSYS FLUENT. Two phases were considered for the flow analysis, and multiphase mixture model was taken into account. The fluid was considered to be a

  11. Preparation of sol-gel derived microcrystalline corundum abrasives with hexagonal platelets

    NASA Astrophysics Data System (ADS)

    Li, Na; Zhu, Yu-Mei; Gao, Kai; Li, Zhi-Hong

    2013-01-01

    The effects of different additives on the mechanical properties, microstructures, and wear behavior of corundum abrasives were investigated. When the number of additive phases increases, the sintering temperature and wear rate decrease, while the densification and mechanical properties increase. The additive SiO2 is responsible for the development of equiaxed grains, whereas both CaO and MgO promote the development of platelike grains. By controlling the molar ratio of additives, it is possible to obtain different microstructures. With SiO2-MgO-CaO (molar ratio, 2:1:1) as the additives and nano α-Al2O3 powders as the seed, microcrystalline corundum abrasives with hexagonal platelets were obtained using sol-gel process by sintering at 1300°C for 0.5 h. The average diameter and thickness of hexagonal platelets are 1.38 μm and 360 nm respectively, the single-particle compressive strength is 26.44 N, and the wear rate is (3.06±0.21)×10-7 mm3/(N·m).

  12. The Effect of Thoracoscopic Pleurodesis in Primary Spontaneous Pneumothorax: Apical Parietal Pleurectomy versus Pleural Abrasion

    PubMed Central

    Huh, Up; Cho, Jeong Su; I, Hoseok; Lee, Jon Geun; Lee, Jun Ho

    2012-01-01

    Background The standard operative treatment of primary spontaneous pneumothorax (PSP) is thoracoscopic wedge resection, but necessity of pleurodesis still remains controversial. Nevertheless, pleural procedure after wedge resection such as pleurodesis has been performed in some patients who need an extremely low recurrence rate. Materials and Methods From January 2000 to July 2010, 207 patients who had undergone thoracoscopic wedge resection and pleurodesis were enrolled in this study. All patients were divided into two groups according to the methods of pleurodesis; apical parietal pleurectomy (group A) and pleural abrasion (group B). The recurrence after surgery had been checked by reviewing medical record through follow-up in ambulatory care clinic or calling to the patients, directly until January 2011. Results Of the 207 patients, the recurrence rate of group A and B was 9.1% and 12.8%, respectively and there was a significant difference (p=0.01, Cox's proportional hazard model). There was no significant difference in age, gender, smoking status, and body mass index between two groups. Conclusion This study suggests that the risk of recurrence after surgery in PSP is significantly low in patients who underwent thoracoscopic wedge resection with parietal pleurectomy than pleural abrasion. PMID:23130305

  13. Effects of enamel abrasion, salivary pellicle, and measurement angle on the optical assessment of dental erosion.

    PubMed

    Lussi, Adrian; Bossen, Anke; Höschele, Christoph; Beyeler, Barbara; Megert, Brigitte; Meier, Christoph; Rakhmatullina, Ekaterina

    2012-09-01

    The present study assessed the effects of abrasion, salivary proteins, and measurement angle on the quantification of early dental erosion by the analysis of reflection intensities from enamel. Enamel from 184 caries-free human molars was used for in vitro erosion in citric acid (pH 3.6). Abrasion of the eroded enamel resulted in a 6% to 14% increase in the specular reflection intensity compared to only eroded enamel, and the reflection increase depended on the erosion degree. Nevertheless, monitoring of early erosion by reflection analysis was possible even in the abraded eroded teeth. The presence of the salivary pellicle induced up to 22% higher reflection intensities due to the smoothing of the eroded enamel by the adhered proteins. However, this measurement artifact could be significantly minimized (p<0.05) by removing the pellicle layer with 3% NaOCl solution. Change of the measurement angles from 45 to 60 deg did not improve the sensitivity of the analysis at late erosion stages. The applicability of the method for monitoring the remineralization of eroded enamel remained unclear in a demineralization/remineralization cycling model of early dental erosion in vitro.

  14. Three-dimensional surface reconstruction for evaluation of the abrasion effects on textile fabrics

    NASA Astrophysics Data System (ADS)

    Mendes, A. O.; Fiadeiro, P. T.; Miguel, R. A. L.

    2006-02-01

    Abrasion is responsible for many surface changes that occur on garments. For this reason, the evaluation of its effects becomes very important for the textile industry. In particular, pilling formation is a phenomenon that results of the abrasion process and affects fabrics more significantly altering their surface severely. The present work presents a method based on optical triangulation that enables topographic reconstructions of textile fabric samples and consequently, makes possible the evaluation and the quantification of the pilling formation that results from their topographic changes. Specific algorithms, written in the MatLab programming language, were developed and implemented to control the image data acquisition, storage and processing procedures. Finally, with the available processed data was possible to reconstruct the surface of fabric samples in three-dimensions and also, a coefficient to express the pilling formation occurred on the analyzed fabrics was achieved. Several tests and experiences have been carried out and the obtained results shown that this method is robust and precise.

  15. 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

  16. An experiment system for testing synergetic erosion caused by sand abrasion and cavitation

    NASA Astrophysics Data System (ADS)

    Lu, L.; Liu, J.; Zhang, J. G.; Zhu, L.; Xu, H. Q.; Meng, X. C.; Yu, J. C.; Ma, S. P.; Wang, K.

    2014-03-01

    An advanced comprehensive test system, designed for testing synergetic erosion due to cavitation and sand abrasion in hydraulic machinery, is presented in this paper. This system includes an integrated test rig, control platform, and state-of-the-art measurement etc. For the integrated test system, there are three test modes, Venturi-section water tunnel, rotating disc and rotating disc with jet nozzle. The maximum velocity is 45 m/s for Venturi-section water tunnel test mode, and 85 m/s for rotating disc test mode. The pressure range for those two test modes can be regulated within -0.09 MPa~0.6 MPa. The highest flow relative velocity is 120 m/s for rotating disc with jet nozzle test mode. All key parameters measured from the test rig, such as flow discharge, pressure, sand concentration, temperature etc, can be displayed online and processed in the control platform. This new test system provides researchers with the possibility to measure cavitation erosion, sand abrasion and the synergetic damage in hydraulic machinery. Further, flow visualization analysis, weight loss measurements and erosion outline measurements are available using the system.

  17. Simulation of abrasive water jet cutting process: Part 1. Unit event approach

    NASA Astrophysics Data System (ADS)

    Lebar, Andrej; Junkar, Mihael

    2004-11-01

    Abrasive water jet (AWJ) machined surfaces exhibit the texture typical of machining with high energy density beam processing technologies. It has a superior surface quality in the upper region and rough surface in the lower zone with pronounced texture marks called striations. The nature of the mechanisms involved in the domain of AWJ machining is still not well understood but is essential for AWJ control improvement. In this paper, the development of an AWJ machining simulation is reported on. It is based on an AWJ process unit event, which in this case represents the impact of a particular abrasive grain. The geometrical characteristics of the unit event are measured on a physical model of the AWJ process. The measured dependences and the proposed model relations are then implemented in the AWJ machining process simulation. The obtained results are in good agreement in the engraving regime of AWJ machining. To expand the validity of the simulation further, a cellular automata approach is explored in the second part of the paper.

  18. Abrasive wear of high velocity oxygen fuel (HVOF) superalloy coatings under vibration load

    NASA Astrophysics Data System (ADS)

    Kandeva, M.; Ivanova, B.; Karastoyanov, D.; Grozdanova, T.; Assenova, E.

    2017-02-01

    The present paper considers wear of coatings deposited by HVOF (High velocity oxy-fuel) technology, under conditions of dry friction against abrasive surface accompanied with the action of vibrations perpendicular to the sliding axis. Results are obtained with four type coatings: two types with Ni matrix of composition 602P – without preliminary heating of the basic surface (the substrate) and after substrate heating up to 650°C in a chamber; coating WC-12Co with tungsten matrix and coating obtained by 1:1 proportion powder mixture of both compositions 602P and WC-12Co. Results about the thickness, hardness and coating’ morphology are presented, as well as dependences of the wear and the relative wear resistance on vibration speeds in the interval 3.03 to 21.08 mm/s. New results are obtained about the nonlinear relationship between abrasive wear and vibration speed showing minimal wear for all specimens by 6.04 mm/s. It is found that lowest wear shows WC-12Co coating in the entire interval of vibration speed variation: 3.03 to 21.08 mm/s. The obtained results are new in the literature; they are not presented and published by the authors.

  19. Study on correlating rain erosion resistance with sliding abrasion resistance of DLC on germanium

    NASA Astrophysics Data System (ADS)

    Gardos, Michael N.; Soriano, Bonnie L.; Propst, Steven H.

    1990-12-01

    Whirling arm rain erosion tests and scanning electron microscope (SEM) tribonietry were performed in parallel with germanium (Ge) flats coated with sputtered DLC films ranging in thickness from 0. 25 zin to ''1 in. Our aim was to establish some correlation between delamination resistance of the DLC under rain drop impact and under environmentallycontrolled tangential shear conditions. The DLC tested at rain erosion velocities of 112 156 and 201 in. s1 (250 350 and 450 mph) showed a correlation between DLC thickness and mnicrofracturecaused delamination where the pit density decreased and pit size increased with coating thickness. Sliding a CVD polycrystalline diamond covered a-SiC pin tip against DLC-coated e flats undr controlled loads speeds and in 1. 33 x 10 Pa (1 x 10 torr) vacuum of the SEM triboineter abrasively removed the thin films inunediately. The thick films lasted for 3 to 10 cycles followed by catastrophic delamination from the wear path in large flakes. The data indicate that delamination of the DLC under any of the test conditions is controlled mainly by the increasing internal stresses developing with progressively higher film thicknesses. These tests served as a prelixainary study using high temperature SEM tribometry measuring abrasion resistance of DLC and polycrystalline diamond films as an approximation for rain erosion resistance under ultrahigh velocity and thermal shock conditions. SPIE Vol. 1325 Diamond Optics /11 (1990) / 99

  20. Alignment of skeletal muscle myoblasts and myotubes using linear micropatterned surfaces ground with abrasives.

    PubMed

    Shimizu, Kazunori; Fujita, Hideaki; Nagamori, Eiji

    2009-06-15

    Alignment of cells plays a significant key role in skeletal muscle tissue engineering because skeletal muscle tissue in vivo has a highly organized structure consisting of long parallel multinucleated myotubes formed through differentiation and fusion of myoblasts. In the present study, we developed an easy, simple, and low-cost method for aligning skeletal muscle cells by using surfaces with linear microscale features fabricated by grinding. Iron blocks were ground in one direction with three kinds of abrasives (9 microm diamond suspension, #400 sandpaper, and #150 sandpaper) and then used as molds to make micropatterned polydimethylsiloxane (PDMS) substrates (type I, type II, and type III). Observation of the surface topography revealed that the PDMS substrates exhibited different degree of mean roughness (Ra), 0.03 microm for type I, 0.16 microm for type II, and 0.56 microm for type III, respectively. Murine skeletal muscle cell line C2C12 myoblasts were cultured and differentiated on the patterned PDMS substrates, and it was examined whether the alignment of C2C12 myoblasts and myotubes was possible. Although the cell growth and differentiation on the three types of patterned substrates were similar to those on the flat PDMS substrate as a control, the alignment of both C2C12 myoblasts and myotubes was obviously observed on types II and III, but not on type I or the control substrate. These results indicate that surfaces ground with abrasives will be useful for fabricating aligned skeletal muscle tissues.

  1. Development and validation of an alternative disturbed skin model by mechanical abrasion to study drug penetration

    PubMed Central

    Schlupp, P.; Weber, M.; Schmidts, T.; Geiger, K.; Runkel, F.

    2014-01-01

    Pharmaceuticals and cosmetics for dermal application are usually tested on healthy skin, although the primary permeation barrier, the stratum corneum, is often impaired by skin diseases or small skin lesions, especially on the hands. These skin conditions can considerably influence the permeation of chemicals and drugs. Furthermore, risk assessment for example of nanoparticles should be performed under various skin conditions to reflect the true circumstances. Therefore, an alternative and reproducible method for a high throughput of skin samples with impaired skin barrier was developed and verified by skin permeation studies (25 h) of caffeine, sorbic acid and testosterone compared to healthy (untreated) and tape-stripped skin. Skin barrier disruption was controlled by TEWL measurement. Skin permeation of the three substances was increased in tape-stripped and abraded skin compared to untreated skin due to the reduced barrier integrity. Enhancement of drug uptake was highest for the most hydrophilic substance, caffeine, followed by sorbic acid and lipophilic testosterone. No significant difference in drug uptake studies was observed between the new abrasion method with an aluminum-coated sponge and the tape-stripping method. The obtained results demonstrate that this abrasion method is an alternative way to achieve a disturbed skin barrier for drug and chemical uptake studies. PMID:25756004

  2. A new methodology for hydro-abrasive erosion tests simulating penstock erosive flow

    NASA Astrophysics Data System (ADS)

    Aumelas, V.; Maj, G.; Le Calvé, P.; Smith, M.; Gambiez, B.; Mourrat, X.

    2016-11-01

    Hydro-abrasive resistance is an important property requirement for hydroelectric power plant penstock coating systems used by EDF. The selection of durable coating systems requires an experimental characterization of coating performance. This can be achieved by performing accelerated and representative laboratory tests. In case of severe erosion induced by a penstock flow, there is no suitable method or standard representative of real erosive flow conditions. The presented study aims at developing a new methodology and an associated laboratory experimental device. The objective of the laboratory apparatus is to subject coated test specimens to wear conditions similar to the ones generated at the penstock lower generatrix in actual flow conditions. Thirteen preselected coating solutions were first been tested during a 45 hours erosion test. A ranking of the thirteen coating solutions was then determined after characterisation. To complete this first evaluation and to determine the wear kinetic of the four best coating solutions, additional erosion tests were conducted with a longer duration of 216 hours. A comparison of this new method with standardized tests and with real service operating flow conditions is also discussed. To complete the final ranking based on hydro-abrasive erosion tests, some trial tests were carried out on penstock samples to check the application method of selected coating systems. The paper gives some perspectives related to erosion test methodologies for materials and coating solutions for hydraulic applications. The developed test method can also be applied in other fields.

  3. Additive manufacturing of tools for lapping glass

    NASA Astrophysics Data System (ADS)

    Williams, Wesley B.

    2013-09-01

    Additive manufacturing technologies have the ability to directly produce parts with complex geometries without the need for secondary processes, tooling or fixtures. This ability was used to produce concave lapping tools with a VFlash 3D printer from 3D Systems. The lapping tools were first designed in Creo Parametric with a defined constant radius and radial groove pattern. The models were converted to stereolithography files which the VFlash used in building the parts, layer by layer, from a UV curable resin. The tools were rotated at 60 rpm and used with 120 grit and 220 grit silicon carbide lapping paste to lap 0.750" diameter fused silica workpieces. The samples developed a matte appearance on the lapped surface that started as a ring at the edge of the workpiece and expanded to the center. This indicated that as material was removed, the workpiece radius was beginning to match the tool radius. The workpieces were then cleaned and lapped on a second tool (with equivalent geometry) using a 3000 grit corundum aluminum oxide lapping paste, until a near specular surface was achieved. By using lapping tools that have been additively manufactured, fused silica workpieces can be lapped to approach a specified convex geometry. This approach may enable more rapid lapping of near net shape workpieces that minimize the material removal required by subsequent polishing. This research may also enable development of new lapping tool geometry and groove patterns for improved loose abrasive finishing.

  4. 'RAT' Leaves a Fine Mess

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This graph shows the light signatures, or spectra, of two sides of the rock dubbed 'Bounce,' located at Meridiani Planum, Mars. The spectra were taken by the miniature thermal emission spectrometer on the Mars Exploration Rover Opportunity. The left side of this rock is covered by fine dust created when the rover drilled into the rock with its rock abrasion tool. These 'fines' produce a layer of pyroxene dust that can be detected here in the top spectrum. The right side of the rock has fewer fines and was used to investigate the composition of this basaltic rock.

  5. Rock Abrasion and Ventifact Formation on Mars from Field Analog, Theoretical, and Experimental Studies

    NASA Technical Reports Server (NTRS)

    Bridges, N. T.; Laity, J. E.

    2001-01-01

    Rocks observed by the Viking Landers and Pathfinder Lander/Sojourner rover exhibit a suite of perplexing rock textures. Among these are pits, spongy textures, penetrative flutes, lineaments, crusts, and knobs Fluvial, impact, chemical alteration, and aeolian mechanisms have been proposed for many of these. In an effort to better understand the origin and characteristics of Martian rock textures, abraded rocks in the Mojave Desert and other regions have been studied. We find that most Martian rock textures, as opposed to just a few, bear close resemblance to terrestrial aeolian textures and can most easily be explained by wind, not other, processes. Flutes, grooves, and some pits on Mars are consistent with abrasion by saltating particles, as described previously. However, many other rock textures probably also have an aeolian origin. Sills at the base of rocks that generally lie at high elevations, such as Half Dome, are consistent with such features on Earth that are related to moats or soil ramps that shield the basal part of the rock from erosion. Crusts consisting of fluted fabrics, such as those on Stimpy and Chimp, are similar to fluted crusts on Earth that spall off over time. Knobby and lineated rocks are similar to terrestrial examples of heterogeneous rocks that differentially erode. The location of specific rock textures on Mars also gives insight into their origin. Many of the most diagnostic ventifacts found at the Pathfinder site are located on rocks that lie near the crests or the upper slopes of ridges. On Earth, the most active ventifact formation occurs on sloped or elevated topography, where windflow is accelerated and particle kinetic energy and flux are increased. Integrated 0 together, these observations point to significant aeolian 0 modification of rocks on Mars and cast doubt on whether many primary textures resulting from other processes are preserved. Experimental simulations of abrasion in the presence of abundant sand indicate that

  6. Studies on parametric optimization for abrasive water jet machining of Al7075-TiB2 in-situ composite

    NASA Astrophysics Data System (ADS)

    Kavya, J. T.; Keshavamurthy, R.; Pradeep Kumar, G. S.

    2016-09-01

    The study focuses on optimization and determination of significant process parameter for Abrasive Water Jet Machining of Al7075-TiB2metal matrix composite. Al-TiB2 metal matrix composite is synthesized by stir casting using in-situ technique. Optimization of machining parameters is done using Taguchi's L25orthogonal array for the experimental trials, with cutting speed, stand-off distance and Abrasive Flow rate as input parameters at five different levels. Analysis Of Variance (ANOVA) method is used for identifying the effect of machining parameters on volumetric material removal rate, surface roughness and dimensional accuracy. Then the results are validated by conducting verification experiments.

  7. Applicability Examination and Evaluation of Reactor Dismantlement Technology in the Fugen: Examination of Double Tubes Cutting by Abrasive Water Jet

    SciTech Connect

    Yasuyuki Nakamura; Kouichi Kikuchi; Yoshitsugu Morishita; Tatsuo Usui; Daisuke Ogane

    2006-07-01

    As a peculiar issue of the decommissioning of FUGEN, it is necessary to establish a dismantlement method for the reactor having a 224 double-tubes structure arranged with pressure and calandria tubes concentrically. Mechanical cutting method will be desirable considering the influence on the atmospheres because the double-tubes consist of highly activated zirconium alloy and zircaloy material. Therefore, the abrasive water jet method was tested and examined as a mechanical double-tube cutting method that needs the standoff comparatively longer. We confirmed the applicability of the abrasive water jet method to the dismantlement of FUGEN's reactor. (authors)

  8. Jetting tool

    SciTech Connect

    Szarka, D.D.; Schwegman, S.L.

    1991-07-09

    This patent describes an apparatus for hydraulically jetting a well tool disposed in a well, the well tool having a sliding member. It comprises positioner means for operably engaging the sliding member of the well tool; and a jetting means, connected at a rotatable connection to the positioner means so that the jetting means is rotatable relative to the positioner means and the well tool, for hydraulically jetting the well tool as the jetting means is rotated relative thereto.

  9. Ablation rate, caries removal, and restoration using Nd:YAG and Er:YAG lasers and air abrasion

    NASA Astrophysics Data System (ADS)

    White, Joel M.

    1998-04-01

    This study evaluated the ablation rate in dentin and enamel of the Nd:YAG laser (1 - 2W, 10Hz) and the Er:YAG laser (1 - 2.5W, 10Hz), compared to the high-speed drill, low-speed drill and air abrasion (fine and extra-fine particle size). Subsequently, the effectiveness of caries removal and restoration in enamel of the Nd:YAG laser at the same powers and pulse repetition rate was compared to the high-speed drill, low-speed drill, and air abrasion. Enamel and dentin of 1mm thick mid-coronal sections from extracted third molars were ablated by Er:YAG laser ((lambda) equals 2.94 micrometer), Nd:YAG laser ((lambda) equals 1.06 micrometer) both with air/water spray, high-speed drill with 300 carbide bur, and low-speed drill with $1/4 round bur and air abrasions at 160 psi, with fine air abrasion at 50 micrometer and extra fine at 27 micrometer particle size. Removal (ablation) rate defined as dentin or enamel thickness divided by time required for perforation of the samples was determined for lasers, drills and air abrasion. Multifactor randomized ANOVA (p less than 0.05) considered removal rate as a function of treatment conditions. Removal Rate (micrometers per second) Enamel Dentin High-speed drill 273 +/- 47.34 493 +/- 1.73 Low-speed drill 0 42 +/- 14.25 Nd:YAG 2W 0 103 +/- 37 Er:YAG 2W 35 +/- 10 348 +/- 101 Air abrasion/fine 220 +/- 27 433 +/- 99 Air abrasion/extra fine 151 +/- 13 203 +/- 30 Er:YAG laser at 2W 10Hz ablated both enamel and dentin faster than the low-speed drill but slower than the high-speed drill, while the Nd:YAG laser at identical power and pulse rate did not ablate healthy enamel but was capable of removing dentin. To determine caries removal rate in enamel, extracted superficial carious molars (n equals 35) that included minimal explorer penetration and radiographic confirmation of caries extent were selected. Samples were randomly distributed into treatment groups: high-speed drill (HS), low-speed drill (LS), Nd:YAG laser (L), Nd:YAG with air

  10. Abrasion and fatigue resistance of PDMS containing multiblock polyurethanes after accelerated water exposure at elevated temperature.

    PubMed

    Chaffin, Kimberly A; Wilson, Charles L; Himes, Adam K; Dawson, James W; Haddad, Tarek D; Buckalew, Adam J; Miller, Jennifer P; Untereker, Darrel F; Simha, Narendra K

    2013-11-01

    Segmented polyurethane multiblock polymers containing polydimethylsiloxane and polyether soft segments form tough and easily processed thermoplastic elastomers (PDMS-urethanes). Two commercially available examples, PurSil 35 (denoted as P35) and Elast-Eon E2A (denoted as E2A), were evaluated for abrasion and fatigue resistance after immersion in 85 °C buffered water for up to 80 weeks. We previously reported that water exposure in these experiments resulted in a molar mass reduction, where the kinetics of the hydrolysis reaction is supported by a straight forward Arrhenius analysis over a range of accelerated temperatures (37-85 °C). We also showed that the ultimate tensile properties of P35 and E2A were significantly compromised when the molar mass was reduced. Here, we show that the reduction in molar mass also correlated with a reduction in both the abrasion and fatigue resistance. The instantaneous wear rate of both P35 and E2A, when exposed to the reciprocating motion of an ethylene tetrafluoroethylene (ETFE) jacketed cable, increased with the inverse of the number averaged molar mass (1/Mn). Both materials showed a change in the wear surface when the number-averaged molar mass was reduced to ≈ 16 kg/mole, where a smooth wear surface transitioned to a 'spalling-like' pattern, leaving the wear surface with ≈ 0.3 mm cracks that propagated beyond the contact surface. The fatigue crack growth rate for P35 and E2A also increased in proportion to 1/Mn, after the molar mass was reduced below a critical value of ≈30 kg/mole. Interestingly, this critical molar mass coincided with that at which the single cycle stress-strain response changed from strain hardening to strain softening. The changes in both abrasion and fatigue resistance, key predictors for long term reliability of cardiac leads, after exposure of this class of PDMS-urethanes to water suggests that these materials are susceptible to mechanical compromise in vivo.

  11. Aeolian Abrasion at the Curiosity Landing Site: Clues to the Role of Wind in Landscape Modification

    NASA Astrophysics Data System (ADS)

    Bridges, N. T.; Le Mouélic, S.; Hallet, B.; Newman, C. E.; Rice, M. S.; Blaney, D. L.; Calef, F. J.; Herkenhoff, K. E.; Langevin, Y.; Lewis, K. W.; Maurice, S.; Pinet, P. C.; Wiens, R. C.; de Pablo, M.; Renno, N. O.

    2013-12-01

    The broad scale geomorphology of Gale Crater reflects diverse aeolian processes, from airfall settling that likely deposited much of the upper and some of the lower units of Mt. Sharp, to evidence of extensive wind exhumation and removal of material exterior to the mound, to active dunes on the crater floor. The integrated effect of aeolian sand transport can also be examined on a much smaller scale by the study of ventifacts, rocks that have been abraded by windborne particles. A diversity of ventifacts are found along Curiosity's traverse through the upper 'hummocky' (HY) geomorphic unit and the lower Yellowknife Bay (YKB) sedimentary rocks. The textures are analogous to abrasion features found on Earth and include cm-scale facets, keels, elongated pits, grooves, flutes, and basal sills. High-resolution images from ChemCam's Remote Micro-Imager also show mm-scale lineations. Evidence of differential erosion is common, with HY conglomerates (e.g., Hottah, Link) and the YKB Sheepbed mudstone unit containing distinct wind tails in the lee of resistant pebbles, and bedding features within Rocknest 3, the YKB Shaler sandstone unit, and other layered rocks displaying prominent ridge-groove topography. ChemCam LIBS depth profile data so far show no strong evidence for chemical differences in the elemental composition between abraded and non-abraded surfaces (as determined from qualitative assessment), as might be expected if there were rock coatings or weathering rinds undergoing active abrasion. Preliminary measurements of ventifact texture and wind tail orientations indicate sandblasting in HY and YKB from predominantly southwesterly and northerly directions, respectively. Based on meso-scale models of current winds and REMS results, SW flow is uncommon whereas N winds are frequent. Compositional and textural information from the suite of MSL instruments indicate that HY rocks are dominated by various types of basalt (either as whole rocks or the resistant clasts in

  12. Lab-scale ash production by abrasion and collision experiments of porous volcanic samples

    NASA Astrophysics Data System (ADS)

    Mueller, S. B.; Lane, S. J.; Kueppers, U.

    2015-09-01

    In the course of explosive eruptions, magma is fragmented into smaller pieces by a plethora of processes before and during deposition. Volcanic ash, fragments smaller than 2 mm, has near-volcano effects (e.g. increasing mobility of PDCs, threat to human infrastructure) but may also cause various problems over long duration and/or far away from the source (human health and aviation matters). We quantify the efficiency of ash generation during experimental fracturing of pumiceous and scoriaceous samples subjected to shear and normal stress fields. Experiments were designed to produce ash by overcoming the yield strength of samples from Tenerife (Canary Islands, Spain), Sicily and Lipari Islands (Italy), with this study having particular interest in the < 355 μm fraction. Fracturing within volcanic conduits, plumes and pyroclastic density currents (PDCs) was simulated through a series of abrasion (shear) and collision (normal) experiments. An understanding of these processes is crucial as they are capable of producing very fine ash (< 10 μm). These particles can remain in the atmosphere for several days and may travel large distances (~ 1000s of km). This poses a threat to the aviation industry and human health. From the experiments we establish that abrasion produced the finest-grained material and up to 50% of the generated ash was smaller than 10 μm. In comparison, the collision experiments that applied mainly normal stress fields produced coarser grain sizes. Results were compared to established grain size distributions for natural fall and PDC deposits and good correlation was found. Energies involved in collision and abrasion experiments were calculated and showed an exponential correlation with ash production rate. Projecting these experimental results into the volcanic environment, the greatest amounts of ash are produced in the most energetic and turbulent regions of volcanic flows, which are proximal to the vent. Finest grain sizes are produced in PDCs

  13. Modeling of cumulative tool wear in machining metal matrix composites

    SciTech Connect

    Hung, N.P.; Tan, V.K.; Oon, B.E.

    1995-12-31

    Metal matrix composites (MMCs) are notoriously known for their low machinability because of the abrasive and brittle reinforcement. Although a near-net-shape product could be produced, finish machining is still required for the final shape and dimension. The classical Taylor`s tool life equation that relates tool life and cutting conditions has been traditionally used to study machinability. The turning operation is commonly used to investigate the machinability of a material; tedious and costly milling experiments have to be performed separately; while a facing test is not applicable for the Taylor`s model since the facing speed varies as the tool moves radially. Collecting intensive machining data for MMCs is often difficult because of the constraints on size, cost of the material, and the availability of sophisticated machine tools. A more flexible model and machinability testing technique are, therefore, sought. This study presents and verifies new models for turning, facing, and milling operations. Different cutting conditions were utilized to assess the machinability of MMCs reinforced with silicon carbide or alumina particles. Experimental data show that tool wear does not depend on the order of different cutting speeds since abrasion is the main wear mechanism. Correlation between data for turning, milling, and facing is presented. It is more economical to rank machinability using data for facing and then to convert the data for turning and milling, if required. Subsurface damages such as work-hardened and cracked matrix alloy, and fractured and delaminated particles are discussed.

  14. Ultrasonically Actuated Tools for Abrading Rock Surfaces

    NASA Technical Reports Server (NTRS)

    Dolgin, Benjamin; Sherrit, Stewart; Bar-Cohen, Yoseph; Rainen, Richard; Askin, Steve; Bickler, Donald; Lewis, Donald; Carson, John; Dawson, Stephen; Bao, Xiaoqi; Chang, Zensheu; Peterson, Thomas

    2006-01-01

    An ultrasonic rock-abrasion tool (URAT) was developed using the same principle of ultrasonic/sonic actuation as that of the tools described in two prior NASA Tech Briefs articles: Ultrasonic/ Sonic Drill/Corers With Integrated Sensors (NPO-20856), Vol. 25, No. 1 (January 2001), page 38 and Ultrasonic/ Sonic Mechanisms for Drilling and Coring (NPO-30291), Vol. 27, No. 9 (September 2003), page 65. Hence, like those tools, the URAT offers the same advantages of low power demand, mechanical simplicity, compactness, and ability to function with very small axial loading (very small contact force between tool and rock). Like a tool described in the second of the cited previous articles, a URAT includes (1) a drive mechanism that comprises a piezoelectric ultrasonic actuator, an amplification horn, and a mass that is free to move axially over a limited range and (2) an abrasion tool bit. A URAT tool bit is a disk that has been machined or otherwise formed to have a large number of teeth and an overall shape chosen to impart the desired shape (which could be flat or curved) to the rock surface to be abraded. In operation, the disk and thus the teeth are vibrated in contact with the rock surface. The concentrated stresses at the tips of the impinging teeth repeatedly induce microfractures and thereby abrade the rock. The motion of the tool induces an ultrasonic transport effect that displaces the cuttings from the abraded area. The figure shows a prototype URAT. A piezoelectric-stack/horn actuator is housed in a cylindrical container. The movement of the actuator and bit with respect to the housing is aided by use of mechanical sliders. A set of springs accommodates the motion of the actuator and bit into or out of the housing through an axial range between 5 and 7 mm. The springs impose an approximately constant force of contact between the tool bit and the rock to be abraded. A dust shield surrounds the bit, serving as a barrier to reduce the migration of rock debris to

  15. Effect of experimental xylitol and fluoride-containing dentifrices on enamel erosion with or without abrasion in vitro.

    PubMed

    Rochel, Isabela D; Souza, Jonas G; Silva, Thiago C; Pereira, Agnes F F; Rios, Daniela; Buzalaf, Marília A R; Magalhães, Ana Carolina

    2011-06-01

    This in vitro study aimed to analyze the effect of including xylitol into a fluoridated dentifrice to provide protection against enamel erosion with or without abrasion. Bovine enamel specimens were subjected to erosion or erosion plus abrasion (7 days) and the treatment with the following dentifrices: 10% xylitol; 10% xylitol plus 1,030 ppm F (NaF); 1,030 ppm F; and placebo. The erosive challenges were performed 4 times a day (2 min at a time). The specimens were exposed to the slurries of the dentifrices 2 times daily (15 s at a time). Half of the specimens per group were additionally abraded using an electrical toothbrush (F = 1.5 N). Between the challenges, the specimens were remineralized by artificial saliva. Enamel loss was measured profilometrically (µm). The data were statistically analyzed by two-way ANOVA and Bonferroni's post-hoc test (P < 0.05). Ten percent xylitol plus F and F dentifrices significantly reduced enamel erosion compared to placebo and xylitol dentifrices. On the other hand, all dentifrices presented a significant potential to protect against enamel erosion plus abrasion compared to placebo, with 10% xylitol plus F showing the best results. Based on this result, the inclusion of 10% xylitol increased the effect of the fluoridated dentifrice against enamel erosion plus abrasion in vitro. In situ or clinical studies are needed to confirm the data.

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

    PubMed

    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.

  17. Abrasive Wear Behavior of WC Reinforced Ni-BASED Composite Coating Sprayed and Fused by Oxy-Acetylene Flame

    NASA Astrophysics Data System (ADS)

    Wang, Qun; Chen, Zhenhua; Ding, Zhang Xiong; Chen, Ding

    Microstructure of WC reinforced Ni-based self-fluxing alloy composite coating sprayed and fused by oxy-acetylene flame was investigated by scanning electron microscopy and energy dispersive X-ray Spectrometry, X-ray diffraction, and transmission electron microscopy. The wear performance of the coating was studied by a MLS-225 wet sand rubber wheel abrasive wear tester at various loads and sizes of abrasive particles. Also, the wear resistance of the coating was compared with uncoated ASTM1020 steel. The results indicated that the coating is bonded metallurgically to the substrate and has a homogeneous microstructure composed of both coarse WC and fine carbide and boride grains such as Cr7C3, Cr23C6, and Ni2B which disperse uniformly in the matrix of γ-Ni solid solution and Ni3B. The worn mass loss of the coating and ASTM1020 steel both increased with the load and size of abrasive particles, also, the coating has exhibited excellent abrasive wear resistance compared with ASTM1020 steel.

  18. Measurements of the Coefficient of Restitution of Quartz Sand on Basalt: Implications for Abrasion Rates on Earth and Mars

    NASA Astrophysics Data System (ADS)

    Banks, M.; Bridges, N. T.; Benzit, M.

    2005-03-01

    Using high speed video to assess grain-rock interactions, it was found that the KE lost on impact is generally proportional to incoming velocity and impact angle, but that only a fraction of this energy goes into direct abrasion of the rock surface.

  19. Public Notice: Saint-Gobain Abrasives, Inc. and Saint-Gobain Ceramics & Plastics, Inc., CWA-01-2016-0057

    EPA Pesticide Factsheets

    Notice of Proposed Assessment of Class II Civil Penalty and Notice of Opportunity for Hearing under Sections 309(g) and 311(b)(6) of the Clean Water Act for Saint-Gobain Abrasives, Inc. and Saint-Gobain Ceramics & Plastics, Inc., CWA-01-2016-0057

  20. Arthroscopic microfracture may not be superior to arthroscopic debridement, but abrasion arthroplasty results are good, although not great.

    PubMed

    Lubowitz, James H

    2015-03-01

    Microfracture is nonanatomic because microfracture destroys the gross structure and the complex microscopic infrastructure of the subchondral plate, and may promote subchondral cyst formation. In consideration of the destruction of subchondral anatomy, it may be time to abandon the arthroscopic microfracture procedure. However, arthroscopic abrasion arthroplasty results in a positive outcome in 66% of patients, and may still merit consideration as a salvage procedure.

  1. The influence of heat treatment on the high-stress abrasion resistance and fracture toughness of alloy white cast irons

    NASA Astrophysics Data System (ADS)

    Sare, I. R.; Arnold, B. K.

    1995-07-01

    The influence of a range of austenitizing and subcritical (tempering) heat treatments on the high-stress abrasion resistance and fracture toughness of four commercially significant grades of alloy white cast iron was investigated. Complementing an earlier study[1] on the influence of a more limited range of heat treatments on the gouging abrasion performance of the same alloys, the results showed that the effect of austenitizing temperature on high-stress abrasion pin test weight loss differed for each alloy. With increasing austenitizing temperature, these results ranged from a substantial improvement in wear performance and retention of hardness through to vir-tually no change in wear performance and substantial falls in hardness. Fracture toughness, however, increased markedly in all alloys with increasing austenitizing temperature. Tempering treatments in the range 400 °C to 600 °C, following hardening at the austenitizing temperature used commonly in industrial practice for each alloy, produced significant changes in both hard-ness and wear performance, but negligible changes in fracture toughness. Most importantly, the data showed that selection of the correct temperature for subcritical heat treatment to reduce the retained austenite content for applications involving repeated impact loading is critical if abrasion resistance is not to suffer.

  2. Neutrophil (PMN) surface contact with keratocytes following corneal epithelial abrasion in the mouse: a novel role for ICAM-1

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corneal epithelial abrasion is associated with an inflammatory response that involves PMN recruitment from the limbal vessels into the corneal stroma. Previously, in the injured mouse cornea, we showed that migrating PMNs not only make contact with collagen, but they also make extensive surface cont...

  3. Clinical study to assess the stain removal efficacy of two tartar control dentifrices and a low abrasive dentifrice.

    PubMed

    Yankell, S L; Emling, R C; Prencipe, M; Rustogi, K; Volpe, A R

    1994-01-01

    Significant differences in stain removal have been demonstrated in a laboratory study comparing two tartar control dentifrices: Platinum, containing 1.3% soluble pyrophosphate and 1.5% of a copolymer, and Crest Tartar Control, containing 5% soluble pyrophosphate. The purpose of this clinical study was to evaluate the same tartar control dentifrices, and a low abrasive dentifrice for their ability to reduce Peridex-induced stain. Eighty-five subjects were given Peridex (0.12% chlorhexidine digluconate) and a low abrasive dentifrice for 4 weeks. The 76 subjects with sufficient stain were stratified using the Lobene index on buccal and lingual surfaces of anterior teeth, and randomly assigned one of the three dentifrices for 8 weeks. At the end of the study, total stain evaluations were significantly lower in the Platinum dentifrice group (mean 0.84) compared to both Crest Tartar Control dentifrice (1.08) and the low abrasive dentifrice (1.09) at p<0.05 by ANOVA. In this 8-week clinical study, Platinum dentifrice was significantly more effective than Crest Tartar Control dentifrice or a low abrasive dentifrice in reducing Peridex-induced stain, and this finding correlates well with laboratory data on removal of tea and coffee stain.

  4. Effects of Nanodiamond Abrasive Friability in Experimental MR Fluids with Phosphate Laser Glass LHG-8 and Other Optical Glasses

    SciTech Connect

    DeGroote, J.E.; Marino, A.E.; Wilson, J.P.; Spencer, K.E.; Jacobs, S.D.

    2005-09-22

    Research is currently being conducted to better understand the role that nanodiamond abrasives play in the removal process of Magnetorheological Finishing (MRF). The following presents removal rate data for a set of six optical glasses that were spotted (not polished out) with four different MR fluids, as well as texturing/smoothing data for phosphate laser glass LHG-8.

  5. Simulation of abrasive water jet cutting process: Part 2. Cellular automata approach

    NASA Astrophysics Data System (ADS)

    Orbanic, Henri; Junkar, Mihael

    2004-11-01

    A new two-dimensional cellular automata (CA) model for the simulation of the abrasive water jet (AWJ) cutting process is presented. The CA calculates the shape of the cutting front, which can be used as an estimation of the surface quality. The cutting front is formed based on material removal rules and AWJ propagation rules. The material removal rule calculates when a particular part of the material will be removed with regard to the energy of AWJ. The AWJ propagation rule calculates the distribution of AWJ energy through CA by using a weighted average. The modelling with CA also provides a visual narrative of the moving of the cutting front, which is hard to observe in real process. The algorithm is fast and has been successfully tested in comparison to cutting fronts obtained with cutting experiments of aluminium alloy.

  6. Mathematical modeling of surface roughness in magnetic abrasive finishing of BK7 optical glass.

    PubMed

    Pashmforoush, Farzad; Rahimi, Abdolreza; Kazemi, Mehdi

    2015-10-01

    Magnetic abrasive finishing (MAF) is one of the advanced machining processes efficiently used to finish hard-to-machine materials. Simulation and modeling of the process is of particular importance to understand the mechanics of material removal and consequently achieve a high-quality surface with a minimum of surface defects. Hence, in this paper, we performed a numerical-experimental study to mathematically model the surface roughness during the MAF of BK7 optical glass. For this purpose, the initial roughness profile was estimated using fast Fourier transform (FFT) and a Gaussian filter. We obtained the final surface profile based on the material removal mechanisms and the corresponding chipping depth values evaluated by finite element analysis. We then validated experimentally the simulation results in terms of the arithmetic average surface roughness (R(a ). The comparison between the obtained results demonstrates that the theoretical and experimental findings are in good agreement when predicting the parameters' effect on surface roughness behavior.

  7. Overview of a new slicing method: Fixed Abrasive Slicing Technique (FAST)

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    The fixed abrasive slicing technique (FAST) was developed to slice silicon ingots more effectively. It was demonstrated that 25 wafers/cm can be sliced from 10 cm diameter and 19 wafers/cm from 15 cm diameter ingots. This was achieved with a combination of machine development and wire-blade development programs. Correlation was established between cutting effectiveness and high surface speeds. A high speed slicer was designed and fabricated for FAST slicing. Wirepack life of slicing three 10 cm diameter ingots was established. Electroforming techniques were developed to control widths and prolong life of wire-blades. Economic analysis indicates that the projected add-on price of FAST slicing is compatible with the DOE price allocation to meet the 1986 cost goals.

  8. Abrasive Wear Failure Analysis of Tungsten Carbide Hard facing on Carbon Steel Blade

    NASA Astrophysics Data System (ADS)

    Tobi, A. L. Mohd; Kamdi, Z.; Ismail, M. I.; Nagentrau, M.; Roslan, L. N. H.; Mohamad, Z.; Omar, A. S.; Latif, N. Abdul

    2017-01-01

    This study investigate the abrasive wear failure of tungsten carbide hardfacing on continuous digester (CD) blade (carbon steel) in an environment of sulphuric acid and ilmenite ore mixture. Comparison being made on the hardness, thickness and microstructural of the hardfacing between unworn and 3 months old worn blade on few locations around the blade. The cross sections of the blade revealed non-uniform coverage of the hardfacing on the blade for both worn and unworn blade. The edge of the blade has the least amount of hardfacing thickness which with time acts as the point of failure during the wear process. The hardness obtained from both the unworn and worn samples are around 25% lower from the hardfacing electrode manufacturer’s hardness specification. Microstructural micrograph analysis of the hardfacing revealed non uniform size carbide with non-uniform distributed of carbide in the hardfacing layer.

  9. Study on subsurface damage of optical glass after grinding with free abrasives

    NASA Astrophysics Data System (ADS)

    Jin, Yuzhu; Jiao, Lingyan; Zhu, Yongwei; Tong, Yi

    2016-10-01

    As a practical engineering device, laser gyro has replaced other types of gyro and become the dominant product of inertial navigation devices, and the mirror substrate is the key part for successful development of laser gyro. Normally, the mirror must have a high reflectivity, for example 99.99% or more, but the premise is that the super smooth surface with the order of Å must be fabricated first 1. In the process of super smooth surface, grinding procedure is a very important step; its quality determines the subsurface damage depth of the mirror. In this paper, based on optical quartz glass as the study object, three different size abrasives are used to grind the blank respectively; then the particle size distribution, surface roughness and microstructure are tested; finally, angle polishing method to measure subsurface damage depth is adopted. Some reasonable theory parameters are obtained through analysis of the test data, also having certain significance for practice.

  10. Scratch and abrasion properties of polyurethane-based micro- and nano-hybrid obturation materials.

    PubMed

    Estevez, Miriam; Rodriguez, J Rogelio; Vargas, Susana; Guerra, J A; Brostow, Witold; Lobland, Haley E Hagg

    2013-06-01

    Polyurethane-based micro- and nano-hybrid composites were produced with controlled porosity to be used as obturation materials. In addition to hydroxyapatite (HAp) micro-particles in the composites, two different ceramics particle types were also added: alumina micro-particles and silica nano-particles. Particles of different sizes provide the materials with improved mechanical properties: the use of micro- and nano-particles produces a better packing because the nano-particles fill the interstitial space left by the micro-particles, rendering an improvement in the mechanical properties. The silica and alumina particles provide the materials with appropriate abrasion and scratching properties, while the HAp provides the required bio-acceptance. The polymeric matrix was a mono-component solvent-free polyurethane. The porosity was selected by controlling the chemical reaction.

  11. Degradation in the Fatigue Resistance of Dentin by Bur and Abrasive Air-jet Preparations

    PubMed Central

    Majd, H.; Viray, J.; Porter, J.A.; Romberg, E.; Arola, D.

    2012-01-01

    The objective of this investigation was to distinguish whether the instruments commonly used for cutting dentin cause degradation in strength or fatigue behavior. Beams of coronal dentin were obtained from unrestored 3rd molars and subjected to either quasi-static or cyclic flexural loading to failure. The surfaces of selected beams were treated with a conventional straight-sided bur or with an abrasive air jet laden with glass particles. Under monotonic loading, there was no difference in the strength or Weibull parameters obtained for the control or treated beams. However, the fatigue strength of dentin receiving bur and air-jet treatments was significantly lower (p ≤ 0.0001) than that of the control. The bur treatment resulted in the largest overall degree of degradation, with nearly 40% reduction in the endurance limit and even more substantial decrease in the fatigue life. The methods currently used for cavity preparations substantially degrade the durability of dentin. PMID:22851284

  12. An acoustic emission study of cutting bauxite refractory ceramics by abrasive water jets

    NASA Astrophysics Data System (ADS)

    Momber, A. W.; Mohan, R. S.; Kovacevic, R.

    1999-08-01

    This article discusses the material removal process in bauxite refractory ceramics cut by abrasive water jets. Several parameters of the process were changed during the experiments. The experiments were monitored online by the acoustic emission (AE) technique. It was found that AE signals are able to sense the material removal process as well as the machining performances very reliably. Unsteady material removal mode consisting of matrix removal and intergranular fracture was very well represented in the AE signals by an unsteady time dependent signal type characterized by burst emissions and a frequency domain signal associated with a twin-peak shape. The particular characteristics of the signal depend on the energy involved in the process.

  13. Machining of Aircraft Titanium with Abrasive-Waterjets for Fatigue Critical Applications

    SciTech Connect

    Liu, H. T.; Hovanski, Yuri; Dahl, Michael E.

    2012-02-01

    Laboratory tests were conducted to determine the fatigue performance of abrasive-waterjet- (AWJ-) machined aircraft titanium. Dog-bone specimens machined with AWJs were prepared and tested with and without sanding and dry-grit blasting with Al2O3 as secondary processes. The secondary processes were applied to remove the visual appearance of AWJ-generated striations and to clean up the garnet embedment. The fatigue performance of AWJ-machined specimens was compared with baseline specimens machined with CNC milling. Fatigue test results of the titanium specimens not only confirmed our previous findings in aluminum dog-bone specimens but in comparison also further enhanced the fatigue performance of the titanium. In addition, titanium is known to be difficult to cut, particularly for thick parts, however AWJs cut the material 34% faster han stainless steel. AWJ cutting and dry-grit blasting are shown to be a preferred ombination for processing aircraft titanium that is fatigue critical.

  14. Basic research needs and opportunities at the solid-solid interface - Adhesion, abrasion and polymer coatings

    NASA Astrophysics Data System (ADS)

    Fowkes, F. M.; Butler, B. L.; Schissel, P.; Butler, G. B.; Hartman, J. S.; Hoffman, R. W.; Inal, O. T.; Miller, W. G.; Tompkins, H. G.; Delollis, N. J.

    1982-04-01

    Solid-solid interfaces in solar technologies such as photovoltaics, mirrored surfaces, and absorbers in flate plate collectors are examined theoretically along with degradation and protective measures. The energetics of adhesion are modeled in terms of intermolecular forces such as covalent and electrostatic bonds. Finite element analyses are noted to be useful for calculating the stress fields in layered solar cells, although inclusion of plastic flow and relaxation processes is not yet possible. The effects of physical degradation of protective coatings and front surfaces of reflectors are outlined, and research in abrasion-erosion resistance, particulate deposition resistance, and detergents for washing solar surfaces is indicated. Finally, polymeric coatings are discussed for solar cells and for wind turbine blades for providing environmental protection.

  15. Surface topography of cylindrical gear wheels after smoothing in abrasive mass, honing and shot peening

    NASA Astrophysics Data System (ADS)

    Michalski, J.; Pawlus, P.; Żelasko, W.

    2011-08-01

    The present paper presents the analysis of surface topography of gear teeth as the result of final machining processes. Teeth of multiple cylindrical gears shaped by grinding were smoothed in abrasive mass, honed or shot peened. The measurement of gears were made using coordinate measuring machine and 3D surface topography stylus instrument. The following deviations were studied; pitch deviation, total pitches deviations, variation of teeth thickness and deviation of gear radial run-out. Changes in teeth surface topography during machining process were determined. 3D surface topography parameters, surface directionality as well as areal autocorrelation and power spectral density functions were taken into consideration. As the results of the analysis, the best surface topography with regard to gear operational properties was recommended.

  16. The role of the microfissuration of the rock matrix in the abrasion resistance of ornamental granitic rocks

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rey, Angel; Sanchez-Delgado, Nuria; Camino, Clara; Calleja, Lope; Ruiz de Argandoña, Vicente G.; Setien, Alexia

    2015-04-01

    The microcrack density and the abrasion resistance of five ornamental granites (Albero, Gris Alba, Mondariz, Rosa Porriño and Traspieles) from Galicia (NW Spain) have been quantified as part of a research aimed to interpret the cuttability of the rocks in relation to the petrophysical properties of the rock matrix. Large blocks from the quarries have been cut with an industrial saw and the microcrack density and the abrasion resistance have been measured in two surfaces: H, parallel to the cut surface; T, perpendicular both to the cut surface and the cutting direction. Both planes are perpendicular to the rift plane, as it is known in quarry works. The microcrack density has been quantified following an stereological procedure applied to polished sections imaged under scanning electron microscopy. The magnification of the images allowed the study of microcracks as narrow as 2 microns in aperture. The density has been quantified in terms of length of microcrack traces per surface unit so possible anisotropies of the microcrack network could be detected. The obtained values are in the typical range for this type of rocks although the Traspieles granite shows a higher value due to its weathering degree (H: 5.11, T: 5.37 mm/mm2). The values measured in the two surfaces (H and T) are quite similar in four of the rocks; only the Albero granite shows a marked anisotropy (H: 2.76 T: 3.53 mm/mm2). The abrasion resistance of the rocks has been measured following the european standard EN 14157:2004 using the capon method. The rocks can be classified in two groups according to their abrasion resistance. Rosa Porriño, Gris Alba and Mondariz granites are the more resistant to abrasion with values around 16-17 mm. Albero and Traspieles granites are less resistant with values higher than 19 mm. The results show a good correlation between the microcrack density and the abrasion resistance. As can be expected the rocks with high microcrack density show low abrasion resistance. The

  17. A quantitative estimation of the exhaust, abrasion and resuspension components of particulate traffic emissions using electron microscopy

    NASA Astrophysics Data System (ADS)

    Weinbruch, Stephan; Worringen, Annette; Ebert, Martin; Scheuvens, Dirk; Kandler, Konrad; Pfeffer, Ulrich; Bruckmann, Peter

    2014-12-01

    The contribution of the three traffic-related components exhaust, abrasion, and resuspension to kerbside and urban background PM10 and PM1 levels was quantified based on the analysis of individual particles by scanning electron microscopy. A total of 160 samples was collected on 38 days between February and September 2009 at a kerbside and an urban background station in the urban/industrial Ruhr area (Germany). Based on size, morphology, chemical composition and stability under electron bombardment, the 111,003 particles studied in detail were classified into the following 14 particle classes: traffic/exhaust, traffic/abrasion, traffic/resuspension, carbonaceous/organic, industry/metallurgy, industry/power plants, secondary particles, (aged) sea salt, silicates, Ca sulfates, carbonates, Fe oxides/hydroxides, biological particles, and other particles. The traffic/exhaust component consists predominantly of externally mixed soot particles and soot internally mixed with secondary particles. The traffic/abrasion component contains all particles with characteristic tracer elements (Fe, Cu, Ba, Sb, Zn) for brake and tire abrasion. The traffic/resuspension component is defined by the mixing state and comprises all internally mixed particles with a high proportion of silicates or Fe oxides/hydroxides which contain soot or abrasion particles as minor constituent. In addition, silicates and Fe oxides/hydroxides internally mixed with chlorine and sulphur containing particles were also assigned to the traffic/resuspension component. The total contribution of traffic to PM10 was found to be 27% at the urban background station and 48% at the kerbside station, the corresponding values for PM1 are 15% and 39%. These values lie within the range reported in previous literature. The relative share of the different traffic components for PM10 at the kerbside station was 27% exhaust, 15% abrasion, and 58% resuspension (38%, 8%, 54% for PM1). For the urban background, the following

  18. Tool Carrier

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Tool organizer accommodates a selection of hand tools on a waist or thigh belt or alternately on wall, work bench, or car trunk mountings. Tool caddy is widely used by industrial maintenance personnel, TV technicians, mechanics, artists, draftsmen, hobbyists and homeowners. Its innovative feature is rows of flexible vinyl "fingers" like the bristles of a hairbrush which mesh together to hold the tool securely in place yet allow easy insertion or withdrawal. Product is no longer commercially available.

  19. Experimental Protocol to Investigate Particle Aerosolization of a Product Under Abrasion and Under Environmental Weathering.

    PubMed

    Shandilya, Neeraj; Le Bihan, Olivier Louis; Bressot, Christophe; Morgeneyer, Martin

    2016-09-16

    The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering, which is a fundamental element to the approach of nanosafety-by-design of nanostructured products for their durable development. This approach is basically a preemptive one in which the focus is put on minimizing the emission of engineered nanomaterials' aerosols during the usage phase of the product's life cycle. This can be attained by altering its material properties during its design phase without compromising with any of its added benefits. In this article, an experimental protocol is presented to investigate the nanosafety-by-design of three commercial nanostructured products with respect to their mechanical solicitation and environmental weathering. The means chosen for applying the mechanical solicitation is an abrasion process and for the environmental weathering, it is an accelerated UV exposure in the presence of humidity and heat. The eventual emission of engineered nanomaterials is studied in terms of their number concentration, size distribution, morphology and chemical composition. The purpose of the protocol is to study the emission for test samples and experimental conditions which are corresponding to real life situations. It was found that the application of the mechanical stresses alone emits the engineered nanomaterials' aerosols in which the engineered nanomaterial is always embedded inside the product matrix, thus, a representative product element. In such a case, the emitted aerosols comprise of both nanoparticles as well as microparticles. But if the mechanical stresses are coupled with the environmental weathering, the experimental protocol reveals then the eventual deterioration of the product, after a certain weathering duration, may lead to the emission of the free engineered nanomaterial aerosols too.

  20. Effect of different fluoride concentrations of experimental dentifrices on enamel erosion and abrasion.

    PubMed

    Moretto, M J; Magalhães, A C; Sassaki, K T; Delbem, A C B; Martinhon, C C R

    2010-01-01

    It has been suggested that fluoride products are able to reduce erosive tooth wear. Thus, the purpose of this in vitro study was to evaluate the effect of dentifrices with different fluoride concentrations as well as of a low-fluoridated dentifrice supplemented with trimetaphosphate (TMP) on enamel erosion and abrasion. One hundred twenty bovine enamel blocks were assigned to the following experimental dentifrices: placebo, 1,100 microg F/g, 500 microg F/g plus 3% TMP and 5,000 microg F/g. The groups of enamel blocks were additionally subdivided into conditions of erosion (ERO) and of erosion plus abrasion (ERO + ABR). For 7 days, the blocks were subjected to erosive challenges (immersion in Sprite 4 times a day for 5 min each time) followed by a remineralizing period (immersion in artificial saliva between erosive challenges for 2 h). After each erosive challenge, the blocks were exposed to slurries of the dentifrices (10 ml/sample for 15 s). Sixty of the blocks were additionally abraded by brushing using an electric toothbrush (15 s). The alterations of the enamel were quantified using the Knoop hardness test and profilometry (measurements in micrometers). The data were analyzed using a 2-way ANOVA test followed by a Bonferroni correction (p < 0.05). In in vitro conditions, the 5,000 microg F/g and 500 microg F/g plus 3% TMP dentifrices had a greater protective effect when compared with the 1,100 microg F/g dentifrice, under both ERO and ERO + ABR conditions. The results suggest that dentifrices alone are not capable of completely inhibiting tooth wear.

  1. Effect of alumina air-abrasion on mechanical bonding between an acrylic resin and casting alloys.

    PubMed

    Ishii, Takaya; Koizumi, Hiroyasu; Tanoue, Naomi; Naito, Koji; Yamashita, Miyuki; Matsumura, Hideo

    2009-06-01

    This study examined the effect of alumina air-abrasion with different pressure on bonding between an acrylic resin and casting alloys. Disk specimens (8 and 10 mm in diameter) were cast from a silver-palladium-copper-gold (Ag-Pd-Cu-Au, Castwell M.C.12) alloy and a titanium-aluminum-niobium alloy (Ti-6Al-7Nb, T-Alloy Tough). The disks were air-abraded with alumina particles (50-70 microm) under different air-pressures (0 unabraded, 0.1, and 0.6 MPa). The disk pairs were bonded together with a tri-n-butylborane (TBB)-initiated acrylic resin, and shear bond strengths were determined both before and after thermocycling. Bond strength varied from a maximum of 37.1 MPa to a minimum of 3.6 MPa for the Ag-Pd-Cu-Au alloy, whereas bond strength to Ti-6Al-7Nb alloy ranged from 34.7 MPa to 0.1 MPa. Specimens abraded with 0.6 MPa pressure recorded the greatest post-thermocycling bond strength (21.7 MPa and 17.9 MPa), and unabraded specimens showed the lowest strength (3.6 MPa and 0.1 MPa) for both alloys. Post-thermocycling bond strength to the Ag-Pd-Cu-Au alloy was higher than that to the Ti-6Al-7Nb alloy under identical air-abrading conditions. It can be concluded that alumina air-abrasion with an air-pressure of 0.6 MPa is effective in enhancing retentive characteristics of the TBB-initiated resin joined to the alloys.

  2. Conventional and anti-erosion fluoride toothpastes: effect on enamel erosion and erosion-abrasion.

    PubMed

    Ganss, C; Lussi, A; Grunau, O; Klimek, J; Schlueter, N

    2011-01-01

    New toothpastes with anti-erosion claims are marketed, but little is known about their effectiveness. This study investigates these products in comparison with various conventional NaF toothpastes and tin-containing products with respect to their erosion protection/abrasion prevention properties. In experiment 1, samples were demineralised (10 days, 6 × 2 min/day; citric acid, pH 2.4), exposed to toothpaste slurries (2 × 2 min/day) and intermittently stored in a mineral salt solution. In experiment 2, samples were additionally brushed for 15 s during the slurry immersion time. Study products were 8 conventional NaF toothpastes (1,400-1,490 ppm F), 4 formulations with anti-erosion claims (2 F toothpastes: NaF + KNO(3) and NaF + hydroxyapatite; and 2 F-free toothpastes: zinc-carbonate-hydroxyapatite, and chitosan) and 2 Sn-containing products (toothpaste: 3,436 ppm Sn, 1,450 ppm F as SnF(2)/NaF; gel: 970 ppm F, 3,030 ppm Sn as SnF(2)). A mouth rinse (500 ppm F as AmF/NaF, 800 ppm Sn as SnCl(2)) was the positive control. Tissue loss was quantified profilometrically. In experiment 1, most NaF toothpastes and 1 F-free formulation reduced tissue loss significantly (between 19 and 42%); the Sn-containing formulations were the most effective (toothpaste and gel 55 and 78% reduction, respectively). In experiment 2, only 4 NaF toothpastes revealed significant effects compared to the F-free control (reduction between 29 and 37%); the F-free special preparations and the Sn toothpaste had no significant effect. The Sn gel (reduction 75%) revealed the best result. Conventional NaF toothpastes reduced the erosive tissue loss, but had limited efficacy regarding the prevention of brushing abrasion. The special formulations were not superior, or were even less effective.

  3. Variability of rock erodibility in bedrock-floored stream channels based on abrasion mill experiments

    NASA Astrophysics Data System (ADS)

    Small, Eric E.; Blom, Tevis; Hancock, Gregory S.; Hynek, Brian M.; Wobus, Cameron W.

    2015-08-01

    We quantify variations in rock erodibility, Kr, within channel cross sections using laboratory abrasion mill experiments on bedrock surfaces extracted from streams with sandstone bedrock in Utah and basaltic bedrock in the Hawaiian Islands. Samples were taken from the thalweg and channel margins, the latter at a height that is inundated annually. For each sample, a sequence of abrasion mill experiments was completed to quantify variations in erosion rate with erosion depth. Erosion rate data from these experiments shows two things. First, the erosion rate from channel margin samples is greater than for thalweg samples, with the greatest difference observed for the rock surface that was exposed in the stream channel. Second, erosion rate decreases with depth beneath the original rock surface, by an order of magnitude in most cases. The erosion rate becomes steady at depths of 1-3 mm for channel margin samples and 0.1-0.4 mm for thalweg samples. Because only rock properties and microtopography vary throughout the sequence of mill experiments, these results suggest that Kr of the bedrock surface exposed in stream channels is higher at the margins than near the channel center and that Kr decreases over depths of ~1 mm. The simplest explanation for these patterns is that Kr is enhanced, at the bedrock surface and along the channel margins, due to the effects of weathering on rock strength and surface roughness. We hypothesize that a balance exists between weathering-enhanced erodibility and episodic incision to allow channel margins to lower at rates similar to the thalweg.

  4. The pro-healing effect of exendin-4 on wounds produced by abrasion in normoglycemic mice.

    PubMed

    Bacci, Stefano; Laurino, Annunziatina; Manni, Maria Elena; Landucci, Elisa; Musilli, Claudia; De Siena, Gaetano; Mocali, Alessandra; Raimondi, Laura

    2015-10-05

    Experimental evidence suggested that Exendin-4 (Exe4), an agonist at glucagon like receptor-1 (GLP-1R), promoted tissue regeneration. We aimed to verify the effect of Exe4, in the absence or in the presence of Exendin-4(9-39), an antagonist at GLP-1R, on the healing of abraded skin. Two wounds (approximately 1.1×1.1 cm(2); namely "upper" and "lower" in respect of the head) were produced by abrasion on the back of 12 mice, which were then randomly assigned to receive an intradermal injection (20 μl) of Group 1: saline (NT) or Exe4 (62 ng) in the upper and lower wound respectively; Group 2: Exendin-4(9-39) (70 ng) in the upper and Exendin-4(9-39) (70 ng) and, after 15 min, Exe4 (62 ng) in the lower wound. Wounds were measured at the time of abrasion (T0) and 144 h (T3) afterward taking pictures with a ruler and by using a software. The inflammatory cell infiltrate, fibroblasts/myofibroblasts, endothelial cells and GLP-1R expression, were each labeled by immunofluorescence in each wound, pERK1/2 was evaluated by Western-blot in wound lysates. At T3, the percentage of healing surface was 53% and 92% for NT and Exe4 wounds respectively and 68% and 79% for those treated with Exendin-4(9-39) and Exendin-4(9-39)+Exe4 respectively. Exe4, but not Exendin-4(9-39) induced quantitative increase in fibroblasts/myofibroblasts and vessel density when compared to NT wounds. This increase was not evident in wounds treated with Exendin-4(9-39)+Exe4. Exe4 promotes wound healing opening to the possible dermatological use of this incretin analogue.

  5. Rock Abrasion on Mars: Clues from the Pathfinder and Viking Landing Sites

    NASA Technical Reports Server (NTRS)

    Bridges, N. T.; Parker, T. J.; Kramer, G. M.

    2000-01-01

    A significant discovery of the Mars Pathfinder (MPF) mission was that many rocks exhibit characteristics of ventifacts, rocks that have been sculpted by saltating particles. Diagnostic features identifying the rocks as ventifacts am elongated pits, flutes, and grooves (collectively referred to as "flutes" unless noted otherwise). Faceted rocks or rock portions, circular pits, rills, and possibly polished rock surfaces are also seen and could be due, to aeolian abrasion. Many of these features were initially identified in rover images, where spatial resolution generally exceeded that of the IMP (Imager for Mars Pathfinder) camera. These images had two major limitations: 1) Only a limited number of rocks were viewed by the rover, biasing flute statistics; and 2) The higher resolution obtained by the rover images and the lack of such pictures at the Viking landing sites hampered comparisons of rock morphologies between the Pathfinder and Viking sites. To avoid this problem, rock morphology and ventifact statistics have been examined using new "super-resolution" IMP and Viking Lander images. Analyses of these images show that: 1) Flutes are seen on about 50% or more of the rocks in the near field at the MPF site; 2) The orientation of these flutes is similar to that for flutes identified in rover images; and 3) Ventifacts are significantly more abundant at the Pathfinder landing site than at the two Viking Landing sites, where rocks have undergone only a limited amount of aeolian abrasion. This is most likely due to the ruggedness of the Pathfinder site and a greater supply of abrading particles available shortly after the Arcs and Tiu Valles outflow channel floods.

  6. Combined Effects of UV Exposure Duration and Mechanical Abrasion on Microplastic Fragmentation by Polymer Type.

    PubMed

    Song, Young Kyoung; Hong, Sang Hee; Jang, Mi; Han, Gi Myung; Jung, Seung Won; Shim, Won Joon

    2017-03-28

    It is important to understand the fragmentation processes and mechanisms of plastic litter to predict microplastic production in the marine environment. In this study, accelerated weathering experiments were performed in the laboratory, with ultraviolet (UV) exposure for up to 12 months followed by mechanical abrasion (MA) with sand for 2 months. Fragmentation of low-density polyethylene (PE), polypropylene (PP), and expanded polystyrene (EPS) was evaluated under conditions that simulated a beach environment. PE and PP were minimally fragmented by MA without photooxidation by UV (8.7 ± 2.5 and 10.7 ± 0.7 particles/pellet, respectively). The rate of fragmentation by UV exposure duration increased more for PP than PE. A 12-month UV exposure and 2-month MA of PP and PE produced 6084 ± 1061 and 20 ± 8.3 particles/pellet, respectively. EPS pellets were susceptible to MA alone (4220 ± 33 particles/pellet), while the combination of 6 months of UV exposure followed by 2 months of MA produced 12,152 ± 3276 particles/pellet. The number of fragmented polymer particles produced by UV exposure and mechanical abrasion increased with decreasing size in all polymer types. The size-normalized abundance of the fragmented PE, PP, and EPS particles according to particle size after UV exposure and MA was predictable. Up to 76.5% of the initial EPS volume was unaccounted for in the final volume of pellet produced particle fragments, indicating that a large proportion of the particles had fragmented into undetectable submicron particles.

  7. Intermittent therapy with terbinafine and nail abrasion for dermatophyte toe onychomycosis: a pilot study.

    PubMed

    Succi, Isabella B; Bernardes-Engemann, Andréa R; Orofino-Costa, Rosane

    2013-05-01

    Onychomycosis constitutes up to 50% of all nail disorders. Toenails are generally affected, mostly due to dermatophytes. Terbinafine is the most potent antifungal agent in vitro against dermatophytes. There are few randomised controlled trials using a non-continuous dose of terbinafine. The aim of this open-label pilot study was to reduce the total drug amount, the collateral effects and, specially, the costs; albeit maintaining the same efficacy of the standard regimens. Compare the outcomes of two different intermittent regimens with the same total amount of the medication (42 tablets in 6 months). Forty-one patients were divided into the following groups: terbinafine 250 mg day(-1) , for 7 days, monthly or terbinafine 500 mg day(-1) , once daily, for 7 days, every 2 months, both plus nail abrasion during 6 months. The efficacy was evaluated at months 6, 12 and 18 using the disease free nail criteria. Total cure = group I: eight patients (44.4%) and group II: eight patients (44.4%). Partial cure = group I: five patients (27.8%) and group II: four patients (22.2%). Treatment failure = group I: five patients (27.8%) and group II: three patients (16.7%). Recurrence = group I: zero patients (0.0%) and group II: three patients (16.7%). Two intermittent dosing regimens of terbinafine plus nail abrasion proved to be an alternative statistically effective, safe and with reduced drug costs for dermatophytes toenail onychomycosis.

  8. 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

  9. Percussion tool

    DOEpatents

    Reed, Teddy R.

    2006-11-28

    A percussion tool is described and which includes a housing mounting a tool bit; a reciprocally moveable hammer borne by the housing and which is operable to repeatedly strike the tool bit; and a reciprocally moveable piston enclosed within the hammer and which imparts reciprocal movement to the reciprocally moveable hammer.

  10. Influence of Erosive and Abrasive Cycling on Bonding of Different Adhesive Systems to Enamel: An In situ Study.

    PubMed

    Giacomini, Marina Ciccone; Casas-Apayco, Leslie Caroll; Machado, Camila Moreira; Freitas, Maria Cristina Carvalho de Almendra; Atta, Maria Teresa; Wang, Linda

    2016-01-01

    This study evaluated the impact of orange juice on the bond strength (BS) of dentin bonding systems (DBSs) to enamel surface after simulation with an in situ/ ex vivo erosive cycling. One hundred and ninety two bovine enamel fragments (4x4x2mm) were obtained and randomized regarding superficial microhardness and distributed to palatal devices for 8 volunteers, in three phases (one for each DBS), containing 8 blocks, which were, allocated in 4 pairs. Daily, these pairs were subjected extraorally to the following conditions: CONT- neither erosive nor abrasive challenge; ERO- erosive challenge only; ABR- abrasive challenge only and ERO + ABR- with erosive and abrasive challenges. Erosive cycles (immersion in orange juice, 3 times/day/5 min/5 days) or/and abrasive challenges (electric toothbrush, 3 times/day/1 min/5 days) were performed. After these cycles, all specimens were restored with the adhesive systems Adper Scotchbond Multi Purpose (MP), Adper Single Bond 2 (SB) or Clearfil SE Bond (SE), and the composite resin Filtek Z250. After 7 days, sticks (area ≅1 mm2) were obtained and subjected to the microtensile bond strength test (μTBS) at 0.5 mm/min. Data was statistically analyzed by ANOVA and Tukey tests (a=0.05). Failure modes were determined using a digital microscope (40´). DBS was the only statistical significant factor. SE was the unique DBS not affected in any challenge, whereas MP and SB performed according to the scenario. The adhesive and mixed failures were predominant in all groups. Overall performance suggested that BS to enamel after erosive /abrasive challenged by orange juice was not affected and it was material-dependent.

  11. Zircon geochronology and ca. 400 Ma exhumation of Norwegian ultrahigh-pressure rocks: An ion microprobe and chemical abrasion study

    USGS Publications Warehouse

    Root, D.B.; Hacker, B.R.; Mattinson, J.M.; Wooden, J.L.

    2004-01-01

    Understanding the formation and exhumation of the remarkable ultrahigh-pressure (UHP) rocks of the Western Gneiss Region, Norway, hinges on precise determination of the time of eclogite recrystallization. We conducted detailed thermal ionization mass spectrometry, chemical abrasion analysis and sensitive high-resolution ion-microprobe analysis of zircons from four ultrahigh- and high-pressure (HP) rocks. Ion-microprobe analyses from the Flatraket eclogite yielded a broad range of apparently concordant Caledonian ages, suggesting long-term growth. In contrast, higher precision thermal ionization mass spectrometry analysis of zircon subject to combined thermal annealing and multi-step chemical abrasion yielded moderate Pb loss from the first (lowest temperature) abrasion step, possible minor Pb loss or minor growth at 400 Ma from the second step and a 407-404 Ma cluster of slightly discordant 206Pb/238U ages, most likely free from Pb loss, from the remaining abrasion steps. We interpret the latter to reflect zircon crystallization at ???405-400 Ma with minor discordance from inherited cores. Zircon crystallization occurred at eclogite-facies, possibly post-peak conditions, based on compositions of garnet inclusions in zircon as well as nearly flat HREE profiles and lack of Eu anomalies in zircon fractions subjected to chemical abrasion. These ages are significantly younger than the 425 Ma age often cited for western Norway eclogite recrystallization, implying faster rates of exhumation (>2.5-8.5 km/Myr), and coeval formation of eclogites across the UHP portion of the Western Gneiss Region. ?? 2004 Published by Elsevier B.V.

  12. Do soil microbes and abrasion by soil particles influence persistence and loss of physical dormancy in seeds of tropical pioneers?

    PubMed

    Zalamea, Paul-Camilo; Sarmiento, Carolina; Arnold, A Elizabeth; Davis, Adam S; Dalling, James W

    2014-01-01

    Germination from the soil seed bank (SSB) is an important determinant of species composition in tropical forest gaps, with seed persistence in the SSB allowing trees to recruit even decades after dispersal. The capacity to form a persistent SSB is often associated with physical dormancy, where seed coats are impermeable at the time of dispersal. Germination literature often speculates, without empirical evidence, that dormancy-break in physically dormant seeds is the result of microbial action and/or abrasion by soil particles. We tested the microbial/soil abrasion hypothesis in four widely distributed neotropical pioneer tree species (Apeiba membranacea, Luehea seemannii, Ochroma pyramidale, and Cochlospermum vitifolium). Seeds were buried in five common gardens in a lowland tropical forest in Panama, and recovered at 1, 3, 6, and 12 months after burial. Seed permeability, microbial infection, seed coat thickness, and germination were measured. Parallel experiments compared the germination fraction of fresh and aged seeds without soil contact, and in seeds as a function of seed permeability. Contrary to the microbial/soil abrasion hypothesis the proportion of permeable seeds, and of seeds infected by cultivable microbes, decreased as a function of burial duration. Furthermore, seeds stored in dark and dry conditions for 2 years showed a higher proportion of seed germination than fresh seeds in identical germination conditions. We determined that permeable seeds of A. membranacea and O. pyramidale had cracks in the chalazal area or lacked the chalazal plug, whereas all surfaces of impermeable seeds were intact. Our results are inconsistent with the microbial/soil abrasion hypothesis of dormancy loss and instead suggest the existence of multiple dormancy phenotypes, where a fraction of each seed cohort is dispersed in a permeable state and germinates immediately, while the impermeable seed fraction accounts for the persistent SSB. Thus, we conclude that fluctuations

  13. Do soil microbes and abrasion by soil particles influence persistence and loss of physical dormancy in seeds of tropical pioneers?

    PubMed Central

    Zalamea, Paul-Camilo; Sarmiento, Carolina; Arnold, A. Elizabeth; Davis, Adam S.; Dalling, James W.

    2015-01-01

    Germination from the soil seed bank (SSB) is an important determinant of species composition in tropical forest gaps, with seed persistence in the SSB allowing trees to recruit even decades after dispersal. The capacity to form a persistent SSB is often associated with physical dormancy, where seed coats are impermeable at the time of dispersal. Germination literature often speculates, without empirical evidence, that dormancy-break in physically dormant seeds is the result of microbial action and/or abrasion by soil particles. We tested the microbial/soil abrasion hypothesis in four widely distributed neotropical pioneer tree species (Apeiba membranacea, Luehea seemannii, Ochroma pyramidale, and Cochlospermum vitifolium). Seeds were buried in five common gardens in a lowland tropical forest in Panama, and recovered at 1, 3, 6, and 12 months after burial. Seed permeability, microbial infection, seed coat thickness, and germination were measured. Parallel experiments compared the germination fraction of fresh and aged seeds without soil contact, and in seeds as a function of seed permeability. Contrary to the microbial/soil abrasion hypothesis the proportion of permeable seeds, and of seeds infected by cultivable microbes, decreased as a function of burial duration. Furthermore, seeds stored in dark and dry conditions for 2 years showed a higher proportion of seed germination than fresh seeds in identical germination conditions. We determined that permeable seeds of A. membranacea and O. pyramidale had cracks in the chalazal area or lacked the chalazal plug, whereas all surfaces of impermeable seeds were intact. Our results are inconsistent with the microbial/soil abrasion hypothesis of dormancy loss and instead suggest the existence of multiple dormancy phenotypes, where a fraction of each seed cohort is dispersed in a permeable state and germinates immediately, while the impermeable seed fraction accounts for the persistent SSB. Thus, we conclude that fluctuations

  14. Modeling and Tool Wear in Routing of CFRP

    SciTech Connect

    Iliescu, D.; Fernandez, A.; Gutierrez-Orrantia, M. E.; Lopez de Lacalle, L. N.

    2011-01-17

    This paper presents the prediction and evaluation of feed force in routing of carbon composite material. In order to extend tool life and improve quality of the machined surface, a better understanding of uncoated and coated tool behaviors is required. This work describes (1) the optimization of the geometry of multiple teeth tools minimizing the tool wear and the feed force, (2) the optimization of tool coating and (3) the development of a phenomenological model between the feed force, the routing parameters and the tool wear. The experimental results indicate that the feed rate, the cutting speed and the tool wear are the most significant factors affecting the feed force. In the case of multiple teeth tools, a particular geometry with 14 teeth right helix right cut and 11 teeth left helix right cut gives the best results. A thick AlTiN coating or a diamond coating can dramatically improve the tool life while minimizing the axial force, roughness and delamination. A wear model has then been developed based on an abrasive behavior of the tool. The model links the feed rate to the tool geometry parameters (tool diameter), to the process parameters (feed rate, cutting speed and depth of cut) and to the wear. The model presented has been verified by experimental tests.

  15. 68Ga and 188Re Starch-Based Microparticles as Theranostic Tool for the Hepatocellular Carcinoma: Radiolabeling and Preliminary In Vivo Rat Studies

    PubMed Central

    Drion, Pierre; Meffre, Geneviève; Bernard, Claire; Duwez, Luc; Lepareur, Nicolas; Couturier, Olivier; Hindré, François

    2016-01-01

    Purpose This work aims to develop, validate and optimize the radiolabeling of Starch-Based Microparticles (SBMP) by 188Re and 68Ga in the form of ready-to-use radiolabeling kits, the ultimate goal being to obtain a unique theranostic vector for the treatment of Hepatocellular Carcinoma. Methods Optimal labeling conditions and composition of freeze-dried kits were defined by monitoring the radiochemical purity while varying several parameters. In vitro stability studies were carried out, as well as an in vivo biodistribution as a preliminary approach with the intra-arterial injection of 68Ga radiolabeled SBMP into the hepatic artery of DENA-induced rats followed by PET/CT imaging. Results Kits were optimized for 188Re and 68Ga with high and stable radiochemical purity (>95% and >98% respectively). The in vivo preliminary study was successful with more than 95% of activity found in the liver and mostly in the tumorous part. Conclusion SBMP are a promising theranostic agent for the Selective Internal Radiation Therapy of Hepatocellular carcinoma. PMID:27741267

  16. Experimental and Morphological Investigations Into Electrical Discharge Surface Grinding (EDSG) of 6061Al/Al2O3p 10% Composite by Composite Tool Electrode

    NASA Astrophysics Data System (ADS)

    Kumar, Harmesh; Choudhary, Rajesh; Singh, Shankar

    2014-04-01

    In this study, a special experimental setup of EDSG using EDM and surface grinding machine has been developed in the laboratory to investigate the effect of seven input parameters namely tool polarity, peak current, pulse on-time, pulse off-time, rotational speed, abrasive particle size, and abrasive particle concentration on material removal rate (MRR) as performance measure of the process. The novelty of the present research work is that successful efforts have been made to machine the 6061Al/Al2O3p 10% metal matrix composites (MMC) by composite tool itself. The copper-based composite tool electrodes were fabricated by powder metallurgy route with different sizes of abrasives of silicon carbide, while 6061Al/Al2O3p 10% MMC were fabricated through stir-casting process. The research outcome will identify the important parameters and their effect on MRR of 6061Al/Al2O3p 10% composite in EDSG. The experimental results reveal that tool polarity, peak current, and rotational speed are the most influential parameters that affect MRR in EDSG process. The micro-structural and morphological analysis of machined surfaces has also been carried out to analyze the surface topography. It has been concluded that the abrasive particles substantially improves the MRR after removing the resolidified layer from the machined surface.

  17. Tumbling experiments to test fragmentation and abrasion of rocks from the Southern Alps, New Zealand

    NASA Astrophysics Data System (ADS)

    Herman, F.; Fluekiger, L.; Cox, S. C.; Beyssac, O.

    2011-12-01

    Detrital cobbles and pebbles were collected from rivers draining the Southern Alps in the South Island of New Zealand. Our objective was to obtain a time-series of abrasion and fragmentation processes, in order to replicate fluvial processes and understand the relative erosion resistance of bedrock lithologies. Lithologies included variably metamorphosed greywacke-sandstone, semischist and schist, reflecting the range of rocks in the hangingwall of the Alpine Fault exhumed by differential uplift, and granite and gneiss in the footwall. Rocks were cut into 3cm cubes, weighed individually and washed in millipore water, then photographed. Experimental sample sets, matching the proportions of rock lithologies observed in the riverbeds, were placed in rectangular 20 litre containers together with 2 litres of fresh rainwater. Containers were rotated in a concrete mixer at 26 revolutions per minute for 2, 4, 12 and 49 hours, with a duplicate geochemical blank sample left for 50 hrs without tumbing. Each set of tumbled material was then extracted, photographed, classified, sorted into size fractions, weighed and saved for further analysis. Samples of sand, silt, rock-contaminated water and suspended sediment were also collected for filtering of suspended sediment, petrography and chemical analysis. Tumbling produced dramatic differences in the behaviour of different rocks, particularly in the relative strength of sandstone, semischist and schist lithologies. Cubes of schist fragmented into tabular pieces and rounded quickly, within two hours, compared with semischist and sandstone which retained cuboid forms and suffered only minor rounding of edges after 49 hours tumbling. Fine-grained material produced as a by-product was dominated by a silt/clay fraction that increased in quantity with tumbling time. Relatively little sand-sized sediment was generated, and its quantity decreased with tumbling time as it was also transformed into finer material. The experiment highlights

  18. Can Wet Rocky Granular Flows Become Debris Flows Due to Fine Sediment Production by Abrasion?

    NASA Astrophysics Data System (ADS)

    Arabnia, O.; Sklar, L. S.; Bianchi, G.; Mclaughlin, M. K.

    2015-12-01

    Debris flows are rapid mass movements in which elevated pore pressures are sustained by a viscous fluid matrix with high concentrations of fine sediments. Debris flows may form from coarse-grained wet granular flows as fine sediments are entrained from hillslope and channel material. Here we investigate whether abrasion of the rocks within a granular flow can produce sufficient fine sediments to create debris flows. To test this hypothesis experimentally, we used a set of 4 rotating drums ranging from 0.2 to 4.0 m diameter. Each drum has vanes along the boundary ensure shearing within the flow. Shear rate was varied by changing drum rotational velocity to maintain a constant Froude Number across drums. Initial runs used angular clasts of granodiorite with a tensile strength of 7.6 MPa, with well-sorted coarse particle size distributions linearly scaled with drum radius. The fluid was initially clear water, which rapidly acquired fine-grained wear products. After each 250 m tangential distance, we measured the particle size distributions, and then returned all water and sediment to the drums for subsequent runs. We calculate particle wear rates using statistics of size and mass distributions, and by fitting the Sternberg equation to the rate of mass loss from the size fraction > 2mm. Abundant fine sediments were produced in the experiments, but very little change in the median grain size was detected. This appears to be due to clast rounding, as evidenced by a decrease in the number of stable equilibrium resting points. We find that the growth in the fine sediment concentration in the fluid scales with unit drum power. This relationship can be used to estimate fine sediment production rates in the field. We explore this approach at Inyo Creek, a steep catchment in the Sierra Nevada, California. There, a significant debris flow occurred in July 2013, which originated as a coarse-grained wet granular flow. We use surveys to estimate flow depth and velocity where super

  19. Lab-scale ash production by abrasion and collision experiments of porous volcanic samples

    NASA Astrophysics Data System (ADS)

    Mueller, Sebastian B.; Lane, Steve J.; Kueppers, Ulrich

    2014-05-01

    In the course of explosive eruptions, magma is fragmented into smaller pieces by a plethora of processes before deposition. Volcanic ash, all fragments smaller than 2 mm, may have imminent and near-volcano effects but may also cause various problems over long duration and/or far away from the source. In an attempt to quantify the efficiency of ash generation, various experimental setups were applied on pumice and scoria samples. We used samples collected on Tenerife (Canary Islands, Spain), Sicily and Lipari Islands (both Italy) for experiments that generated shear or normal stress fields or combinations of these within the rock samples. Experiments were designed to overcome low yield strengths of samples and produce ash, with this study having particular interest in the < 355 µm fraction. By abrasion and collision experiments, the processes that are likely to happen within volcanic conduits, plumes or pyroclastic density currents (PDCs) were simulated. An understanding of these secondary fragmentation processes is crucial as they are capable of producing very fine ash, with size ranges from a few microns to few millimetres. These particles are known to remain in the atmosphere for several days and travel large distances (~ 100s of km). This poses threats to the aviation industry and human health. From the experiments we establish that abrasion setups produced the finest material and up to 50% of the generated ash was smaller than 10 µm. In comparison, the drop experiments that applied mainly normal stress fields produced coarser grain sizes. Results were compared to grain size distributions described in literature for natural fall and PDC deposits and good correlation was found. Energies involved in drop experiments were calculated and showed an exponential correlation with ash production rate. Projecting these results into the actual volcanic environment, highest amounts of ash are produced in most energetic and turbulent areas, which are proximal to the vent

  20. GRIPPING TOOL

    DOEpatents

    Sandrock, R.J.

    1961-12-12

    A self-actuated gripping tool is described for transferring fuel elements and the like into reactors and other inaccessible locations. The tool will grasp or release the load only when properly positioned for this purpose. In addition, the load cannot be released except when unsupported by the tool, so that jarring or contact will not bring about accidental release of the load. The gripping members or jaws of the device are cam-actuated by an axially slidable shaft which has two lockable positions. A spring urges the shaft into one position and a solenoid is provided to overcome the spring and move it into the other position. The weight of the tool operates a sleeve to lock the shaft in its existing position. Only when the cable supporting the tool is slack is the device capable of being actuated either to grasp or release its load. (AEC)

  1. Omics Tools

    SciTech Connect

    Schaumberg, Andrew

    2012-12-21

    The Omics Tools package provides several small trivial tools for work in genomics. This single portable package, the “omics.jar” file, is a toolbox that works in any Java-based environment, including PCs, Macs, and supercomputers. The number of tools is expected to grow. One tool (called cmsearch.hadoop or cmsearch.local), calls the external cmsearch program to predict non-coding RNA in a genome. The cmsearch program is part of the third-party Infernal package. Omics Tools does not contain Infernal. Infernal may be installed separately. The cmsearch.hadoop subtool requires Apache Hadoop and runs on a supercomputer, though cmsearch.local does not and runs on a server. Omics Tools does not contain Hadoop. Hadoop mat be installed separartely The other tools (cmgbk, cmgff, fastats, pal, randgrp, randgrpr, randsub) do not interface with third-party tools. Omics Tools is written in Java and Scala programming languages. Invoking the “help” command shows currently available tools, as shown below: schaumbe@gpint06:~/proj/omics$ java -jar omics.jar help Known commands are: cmgbk : compare cmsearch and GenBank Infernal hits cmgff : compare hits among two GFF (version 3) files cmsearch.hadoop : find Infernal hits in a genome, on your supercomputer cmsearch.local : find Infernal hits in a genome, on your workstation fastats : FASTA stats, e.g. # bases, GC content pal : stem-loop motif detection by palindromic sequence search (code stub) randgrp : random subsample without replacement, of groups randgrpr : random subsample with replacement, of groups (fast) randsub : random subsample without replacement, of file lines For more help regarding a particular command, use: java -jar omics.jar command help Usage: java -jar omics.jar command args

  2. Enhancing effects of sericin on corneal wound healing in Otsuka Long-Evans Tokushima fatty rats as a model of human type 2 diabetes.

    PubMed

    Nagai, Noriaki; Murao, Takatoshi; Ito, Yoshimasa; Okamoto, Norio; Sasaki, Masahiro

    2009-09-01

    The protein sericin is the main constituent of silk. We investigated the effects of sericin on corneal wound healing in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model for human type 2 diabetes. Corneal wounds were prepared by removal of the corneal epithelium, and documented using a TRC-50X equipped with a digital camera. Sericin solutions were instilled into the eyes of rats five times a day following corneal abrasion. Plasma glucose and triglycerides were determined using an Accutrend GCT. Cholesterol and insulin were measured using a Cholesterol E-Test Kit and ELISA Insulin Kit, respectively. The plasma levels of glucose, triglycerides, cholesterol and insulin in 38-week-old OLETF rats were significantly higher than in Long-Evans Tokushima Otsuka (LETO) rats used as normal controls, and the rate of corneal wound healing in OLETF rats was slower than in LETO rats. The corneal wounds of rats instilled with saline showed almost complete healing by 72 h after corneal epithelial abrasion. On the other hand, the corneal healing rate of OLETF rats instilled with 10% sericin solution was significantly higher than that of LETO rats instilled with saline, and the wounds showed almost complete healing at 48 h after abrasion. The corneal healing rate increased with increasing sericin concentration. The present study demonstrates that the corneal wound healing rate in OLETF rat is slower than in LETO rats, and the instillation of sericin solution has a potent effect in promoting wound healing and wound-size reduction in LETO and OLETF rats.

  3. Microstructures and Abrasive Properties of the Oxide Coatings on Al6061 Alloys Prepared by Plasma Electrolytic Oxidation in Different Electrolytes

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Byun, Sangsik; Lee, Chan Gyu; Koo, Bon Heun; Wang, Yi Qi; Song, Jung Il

    Al2O3 coatings were prepared on T6-tempered Al6061 alloys substrate under a hybrid voltage (AC 200 V-60 Hz and DC 260 V value) by plasma electrolytic oxidation (PEO) in 30 min. The effects of different electrolytes on the abrasive behaviors of the coatings were studied by conducting dry ball-on-disk wear tests. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the coating microstructure. XRD analysis results show that the coatings mainly consist of α- and γ-Al2O3, and some mullite and AlPO4 phase in Na2SiO3 and Na3PO4 containing electrolytes, respectively. The wear test results show that the coatings which were PEO-treated in Na3PO4 containing electrolyte presented the most excellent abrasive resistance property.

  4. A comparison of the tribological behaviour of Y-TZP in tea and coffee under micro-abrasion conditions

    NASA Astrophysics Data System (ADS)

    Sharifi, S.; Stack, M. M.

    2013-10-01

    The micro-abrasion of Y-TZP, a candidate dental restorative material, was investigated in a range of caffeine-containing solutions which included tea and coffee. Additions of sugar and milk were used to test the effects of viscosity and pH on the wear rate. The results indicated a significant increase in wear rate in the various solutions, with some correlation between wear rate and increases in viscosity and this was linked to enhance particle entrainment in the more viscous solutions. The generally lower wear rate in tea compared to coffee was associated with a longer ageing period in this solution before uniform wear was observed. Micro-abrasion maps were used to characterize the differences in performance for the material in the environments studied.

  5. Surface Analysis and Tools

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2002-01-01

    This article is a chapter of the book entitled, "Tribology of Mechanical Systems," to be published by ASME Press, New York, NY. It describes selected analytical techniques, which are being used in understanding phenomena and mechanisms of oxidation, adhesion, bonding, friction, erosion, abrasion, and wear, and in defining the problems. The primary emphasis is on microanalytical approaches to engineering surfaces.

  6. 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.

  7. Effect of Toothpastes with Different Abrasives on Eroded Human Enamel: An in situ/ex vivo Study

    PubMed Central

    Ferreira, Meire Coelho; Ramos-Jorge, Maria Letícia; Delbem, Alberto Carlos Botazzo; Vieirac, Ricardo de Sousa

    2013-01-01

    The aim of the present study was to investigate the abrasive effect of CaCO3 and SiO2-based fluoride-free experimental toothpastes on eroded human permanent dental enamel and evaluate the effectiveness of waiting periods between acid exposure and tooth brushing. Twelve volunteers wore palatal appliances containing human enamel blocks for two periods of five days each. The appliances were immersed in a soft drink for five minutes four times a day (9:00 am, 11:00 am, 2:00 pm and 4:00 pm). On two occasions, two blocks were not submitted to additional treatment; two blocks were brushed (30 s) either with a CaCO3 or SiO2 toothpaste immediately after erosion and two blocks were brushed 1 h after erosion. Thus, the sample was divided into six groups: erosion alone (CaCO3 and SiO2 control); brushing with fluoride-free toothpaste (CaCO3 immediate and 1 h after erosion; SiO2 immediate and 1 h after erosion). Significant differences in wear depth were found between the enamel blocks in the CaCO3 immediate and 1 h after erosion groups and the blocks in the CaCO3 control group (p=0.001; p=0.022). No significant differences were found regarding the change in roughness and wear depth between blocks submitted to immediate abrasion and 1 h after erosion (CaCO3 and SiO2). The data revealed that surface roughness and wear depth is increased when erosion is combined with dental abrasion, regardless of the abrasive used. Waiting for 1 h to brush the eroded blocks offered no protective effect. PMID:24198851

  8. Cutting concrete with abrasive waterjets. Phase 1: evaluation of relatively low pressure water-jet performance. Final report

    SciTech Connect

    Yie, G.G.

    1986-01-01

    In laboratory testing, a prototype low-pressure abrasive water-jet system proved more effective in cutting concrete and asphalt than the high-pressure systems tested before. Projected operating costs for the hand-carried unit - a fraction of those of conventional concrete saws and carbide cutting wheels - could mean savings between $15,000 and $20,000 per mile of cut.

  9. Application of Abrasive-Waterjets for Machining Fatigue-Critical Aircraft Aluminum Parts

    SciTech Connect

    Liu, H T; Hovanski, Yuri; Dahl, Michael E; Zeng, J

    2010-08-19

    Current specifications require AWJ-cut aluminum parts for fatigue critical aerospace structures to go through subsequent processing due to concerns of degradation in fatigue performance. The requirement of secondary process for AWJ-machined parts greatly negates the cost effectiveness of waterjet technology. Some cost savings are envisioned if it can be shown that AWJ net cut parts have comparable durability properties as those conventionally machined. To revisit and upgrade the specifications for AWJ machining of aircraft aluminum, “Dog-bone” specimens, with and without secondary processes, were prepared for independent fatigue tests at Boeing and Pacific Northwest National Laboratory (PNNL). Test results show that the fatigue life is proportional to quality levels of machined edges or inversely proportional to the surface roughness Ra . Even at highest quality level, the average fatigue life of AWJ-machined parts is about 30% shorter than those of conventionally machined counterparts. Between two secondary processes, dry-grit blasting with aluminum oxide abrasives until the striation is removed visually yields excellent result. It actually prolongs the fatigue life of parts at least three times higher than that achievable with conventional machining. Dry-grit blasting is relatively simple and inexpensive to administrate and, equally important, alleviates the concerns of garnet embedment.

  10. 3D Imaging of Diatoms with Ion-abrasion Scanning Electron Microscopy

    PubMed Central

    Hildebrand, Mark; Kim, Sang; Shi, Dan; Scott, Keana; Subramaniam, Sriram

    2009-01-01

    Ion-abrasion scanning electron microscopy (IASEM) takes advantage of focused ion beams to abrade thin sections from the surface of bulk specimens, coupled with SEM to image the surface of each section, enabling 3D reconstructions of subcellular architecture at ~ 30 nm resolution. Here, we report the first application of IASEM for imaging a biomineralizing organism, the marine diatom Thalassiosira pseudonana. Diatoms have highly patterned silica-based cell wall structures that are unique models for the study and application of directed nanomaterials synthesis by biological systems. Our study provides new insights into the architecture and assembly principles of both the “hard” (siliceous) and “soft” (organic) components of the cell. From 3D reconstructions of developmentally synchronized diatoms captured at different stages, we show that both micro- and nanoscale siliceous structures can be visualized at specific stages in their formation. We show that not only are structures visualized in a whole-cell context, but demonstrate that fragile, early-stage structures are visible, and that this can be combined with elemental mapping in the exposed slice. We demonstrate that the 3D architectures of silica structures, and the cellular components that mediate their creation and positioning can be visualized simultaneously, providing new opportunities to study and manipulate mineral nanostructures in a genetically tractable system. PMID:19269330

  11. Self-healing Characteristics of Collagen Coatings with Respect to Surface Abrasion.

    PubMed

    Kim, Chang-Lae; Kim, Dae-Eun

    2016-03-24

    A coating based on collagen with self-healing properties was developed for applications in mechanical components that are prone to abrasion due to contact with a counter surface. The inherent swelling behavior of collagen in water was exploited as the fundamental mechanism behind self-healing of a wear scar formed on the surface. The effects of freeze-drying process and water treatment of the collagen coatings on their mechanical and self-healing properties were analyzed. Water was also used as the medium to trigger the self-healing effect of the collagen coatings after the wear test. It was found that collagen coatings without freeze-drying did not demonstrate any self-healing effect whereas the coatings treated by freeze-drying process showed remarkable self-healing effect. Overall, collagen coatings that were freeze-dried and water treated showed the best friction and self-healing properties. Repeated self-healing ability of these coatings with respect to wear scar was also demonstrated. It was also confirmed that the self-healing property of the collagen coating was effective over a relatively wide range of temperature.

  12. AIBA as Free Radical Initiator for Abrasive-Free Polishing of Hard Disk Substrate

    NASA Astrophysics Data System (ADS)

    Lei, Hong; Ren, Xiaoyan

    2015-04-01

    In order to optimize the existing slurry for abrasive-free polishing (AFP) of a hard disk substrate, a water-soluble free radical initiator, 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AIBA) was introduced into H2O2-based slurry in the present work. Polishing experiment results with AIBA in the H2O2 slurry indicate that the material removal rate (MRR) increases and the polished surface has a lower surface roughness. The mechanism of AIBA in AFP was investigated using electron spin-resonance spectroscopy and UV-Visible analysis, which showed that the concentration of hydroxyl radical (a stronger oxidizer than H2O2) in the slurry was enhanced in the present of AIBA. The structure of the film formed on the substrate surface was investigated by scanning electron microscopy, auger electron spectroscopy and electrochemical impedance spectroscopy technology, showing that a looser and porous oxide film was found on the hard disk substrate surface when treated with the H2O2-AIBA slurry. Furthermore, potentiodynamic polarization tests show that the H2O2-AIBA slurry has a higher corrosion current density, implying that a fast dissolution reaction can occur on the substrate surface. Therefore, we can conclude that the stronger oxidation ability, loose oxide film on the substrate surface, and the higher corrosion-wear rate of the H2O2-AIBA slurry lead to the higher MRR.

  13. An alternatively spliced IL-15 isoform modulates abrasion-induced keratinocyte activation.

    PubMed

    Lee, Tsung-Lin; Chang, Mei-Ling; Lin, Yu-Jei; Tsai, Ming-Hsun; Chang, Yi-Hsuan; Chuang, Che-Ming; Chien, Yun; Sosinowski, Tomasz; Wang, Chih-Hsiu; Chen, Yi-Yuan; Lee, Chien-Kuo; Chen, Jau-Shiuh; Wang, Li-Fang; Kung, John T; Ku, Chia-Chi

    2015-05-01

    In a routine phenotype-driven screen, we identified a point mutation in exon 7 of the IL-15 gene in Pedigree 191 (deficient memory (DM)) of N-ethyl-N-nitrosourea mutagenized mice. The DM epidermis expressed an alternatively spliced IL-15 mRNA isoform, IL-15ΔE7, and a wild-type (WT) IL-15 isoform at comparable levels. Mechanical stimulation of DM skin or DM skin graft transplanted onto the WT host resulted in reduced keratinocyte activation and inhibition of neutrophil infiltration into the dermis, demonstrating that DM keratinocytes produced less inflammatory response to external stimulation. Ectopic expression of IL-15ΔE7 in WT skin prevented abrasion-induced epidermal thickening, blocked the accumulation of nuclear antigen Ki67(+) cells in the basal and the suprabasal cell layers, increased loricrin expression, and also increased keratinocyte CXCL1 and G-CSF production. IL-15ΔE7 also profoundly blocked neutrophil infiltration in SDS- or immiquimod (IMQ)-treated WT skin. Recombinant IL-15ΔE7 failed to activate STAT-5 and its downstream target bcl-2 expression. Our study points to IL-15ΔE7 as a potential therapeutic agent for treating neutrophilia-associated inflammatory skin disorders.

  14. 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.

  15. Abrasive jet micro-machining of planar areas and transitional slopes

    NASA Astrophysics Data System (ADS)

    Ghobeity, A.; Spelt, J. K.; Papini, M.

    2008-05-01

    Analytical and computer models are presented to predict the evolution of planar areas and transitional slopes micromachined in glass using abrasive jet micro-machining. The energy distributions across a rectangular and a round nozzle were found to be non-uniform and therefore unsuitable to machine flat surfaces in a single pass. Consequently, a simple model was developed to guide the computer-controlled machining of an approximately flat surface, by the use of multiple passes arranged in such a manner that the summation of their energy distributions gave a uniform energy flux to the surface. Planar areas were machined in glass, and there was good agreement between the model predictions and experimentally measured surface profiles. Masked planar areas were also machined, and it was found that particle scattering by the mask edge (Ghobeity, Krajac, Burzynski, Papini and Spelt 2008 Wear 264 185-98) caused the sidewalls of the planar area to be very shallow, on the order of only a few degrees. A novel method is presented to increase the slope at the edges of such masked planar areas. Although the methods are demonstrated through the micro-machining of flat, planar areas, they are equally applicable to the production of inclined planar areas and arbitrarily curved surfaces.

  16. Contributions of nanodiamond abrasives and deionized water in magnetorheological finishing of aluminum oxynitriden

    NASA Astrophysics Data System (ADS)

    Miao, Chunlin; Lambropoulos, John C.; Romanofsky, Henry; Shafrir, Shai N.; Jacobs, Stephen D.

    2009-08-01

    Magnetorheological finishing (MRF) is a sub-aperture deterministic process for fabricating high-precision optics by removing material and smoothing the surface. The goal of this work is to study the relative contribution of nanodiamonds and water in material removal for MRF of aluminum oxynitride ceramic (ALON) based upon a nonaqueous magnetorheological (MR) fluid. Removal was enhanced by a high carbonyl iron concentration and the addition of nanodiamond abrasives. Small amounts of deionized (DI) water were introduced into the nonaqueous MR fluid to further influence the material removal process. Material removal data were collected with a spot-taking machine. Drag force (Fd) and normal force (Fn) before and after adding nanodiamonds or DI water were measured with a dual load cell. Both drag force and normal force were insensitive to the addition of nanodiamonds but increased with DI water content in the nonaqueous MR fluid. Shear stress (i.e., drag force divided by spot area) was calculated, and examined as a function of nanodiamond concentration and DI water concentration. Volumetric removal rate increased with increasing shear stress, which was shown to be a result of increasing viscosity after adding nanodiamonds and DI water. This work demonstrates that removal rate for a hard ceramic with MRF can be enhanced by adding DI water into a nonaqueous MR fluid.

  17. Self-healing Characteristics of Collagen Coatings with Respect to Surface Abrasion

    PubMed Central

    Kim, Chang-Lae; Kim, Dae-Eun

    2016-01-01

    A coating based on collagen with self-healing properties was developed for applications in mechanical components that are prone to abrasion due to contact with a counter surface. The inherent swelling behavior of collagen in water was exploited as the fundamental mechanism behind self-healing of a wear scar formed on the surface. The effects of freeze-drying process and water treatment of the collagen coatings on their mechanical and self-healing properties were analyzed. Water was also used as the medium to trigger the self-healing effect of the collagen coatings after the wear test. It was found that collagen coatings without freeze-drying did not demonstrate any self-healing effect whereas the coatings treated by freeze-drying process showed remarkable self-healing effect. Overall, collagen coatings that were freeze-dried and water treated showed the best friction and self-healing properties. Repeated self-healing ability of these coatings with respect to wear scar was also demonstrated. It was also confirmed that the self-healing property of the collagen coating was effective over a relatively wide range of temperature. PMID:27010967

  18. Self-healing Characteristics of Collagen Coatings with Respect to Surface Abrasion

    NASA Astrophysics Data System (ADS)

    Kim, Chang-Lae; Kim, Dae-Eun

    2016-03-01

    A coating based on collagen with self-healing properties was developed for applications in mechanical components that are prone to abrasion due to contact with a counter surface. The inherent swelling behavior of collagen in water was exploited as the fundamental mechanism behind self-healing of a wear scar formed on the surface. The effects of freeze-drying process and water treatment of the collagen coatings on their mechanical and self-healing properties were analyzed. Water was also used as the medium to trigger the self-healing effect of the collagen coatings after the wear test. It was found that collagen coatings without freeze-drying did not demonstrate any self-healing effect whereas the coatings treated by freeze-drying process showed remarkable self-healing effect. Overall, collagen coatings that were freeze-dried and water treated showed the best friction and self-healing properties. Repeated self-healing ability of these coatings with respect to wear scar was also demonstrated. It was also confirmed that the self-healing property of the collagen coating was effective over a relatively wide range of temperature.

  19. Planarization process of single crystalline silicon asperity under abrasive rolling effect studied by molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Si, Lina; Guo, Dan; Luo, Jianbin; Xie, Guoxin

    2012-10-01

    In the chemical mechanical polishing (CMP) process, the complex behaviors of abrasive particles play important roles in the planarization of wafer surface. Particles embedded in the pad remove materials by ploughing, while particles immersed in the slurry by rolling across the wafer surface. In this paper, processes of the particle rolling across a silicon surface with an asperity under various down forces and external driving forces were studied using molecular dynamics (MD) simulation method. The simulations clarified the asperity shape evolution during the rolling process and analyzed the energy changes of the simulation system and the interaction forces acted on the silica particle. It was shown that both the down force and the driving force had important influences on the amount of the material removed. With relatively small down forces and driving forces applied on the particle, the material removal occurred mainly in the front end of the asperity; when the down forces and driving forces were large enough, e.g., 100 nN, the material removal could take place at the whole top part of the asperity. The analysis of energy changes and interaction forces provided favorable explanations to the simulation results.

  20. Monitoring and Testing the Parts Cleaning Stations, Abrasive Blasting Cabinets, and Paint Booths

    NASA Technical Reports Server (NTRS)

    Jordan, Tracee M.

    2004-01-01

    I have the opportunity to work in the Environmental Management Office (EMO) this summer. One of the EMO's tasks is to make sure the Environmental Management System is implemented to the entire Glenn Research Center (GRC). The Environmental Management System (EMS) is a policy or plan that is oriented toward minimizing an organization's impact to the environment. Our EMS includes the reduction of solid waste regeneration and the reduction of hazardous material use, waste, and pollution. With the Waste Management Team's (WMT) help, the EMS can be implemented throughout the NASA Glenn Research Center. The WMT is responsible for the disposal and managing of waste throughout the GRC. They are also responsible for the management of all chemical waste in the facility. My responsibility is to support the waste management team by performing an inventory on parts cleaning stations, abrasive cabinets, and paint booths through out the entire facility. These booths/stations are used throughout the center and they need to be monitored and tested for hazardous waste and material. My job is to visit each of these booths/stations, take samples of the waste, and analyze the samples.

  1. Target responses to the impact of high-velocity, non-abrasive water jets

    SciTech Connect

    Kang, S.W.; Reitter, T.; Carlson, G.; Crutchmer, J.; Garrett, D.; Kramer, P.; Do, B.

    1993-04-01

    Theoretical and experimental investigations have been performed on the effects of a non-abrasive water jet impinging on a solid surface. The theoretical analysis treats the time-dependent, twodimensional case of an axisymmetric jet impacting on a rigid or non-rigid surface at various velocities, up to 1500 m/s. The numerical results obtained include time-dependent pressure distributions and jet geometry near the surface. The maximum calculated pressures agree well with the ``water-hammer`` values when modified for high-velocity jets. Impact and machining experiments were conducted with various materials with water jet reservoir pressures up to 276 MPa (40,000 psi). Test results show that maximum mass removal rate takes place when the standoff distance is several hundred nozzle diameters from the nozzle, suggesting that at this long distance the jet has disintegrated into a series of ligaments and drops impinging on the surface. Analytical and experimental efforts are continuing on determining the dominant mechanisms for the target response to high-velocity jets.

  2. Target responses to the impact of high-velocity, non-abrasive water jets

    SciTech Connect

    Kang, S.W.; Reitter, T.; Carlson, G. ); Crutchmer, J.; Garrett, D.; Kramer, P.; Do, B. )

    1993-04-01

    Theoretical and experimental investigations have been performed on the effects of a non-abrasive water jet impinging on a solid surface. The theoretical analysis treats the time-dependent, twodimensional case of an axisymmetric jet impacting on a rigid or non-rigid surface at various velocities, up to 1500 m/s. The numerical results obtained include time-dependent pressure distributions and jet geometry near the surface. The maximum calculated pressures agree well with the water-hammer'' values when modified for high-velocity jets. Impact and machining experiments were conducted with various materials with water jet reservoir pressures up to 276 MPa (40,000 psi). Test results show that maximum mass removal rate takes place when the standoff distance is several hundred nozzle diameters from the nozzle, suggesting that at this long distance the jet has disintegrated into a series of ligaments and drops impinging on the surface. Analytical and experimental efforts are continuing on determining the dominant mechanisms for the target response to high-velocity jets.

  3. The abrasive wear of plasma sprayed nanoscale tungsten carbide-cobalt (WC-Co)

    NASA Astrophysics Data System (ADS)

    Tewksbury, Graham Alfred

    Thermal spray coatings composed of a variety of carbide sizes and cobalt contents were sprayed with a high energy plasma spray system. The size of the carbides used fell into three rough groupings, micrometer scale carbides (1--2 mum), submicrometer (700--300 nm), and nanoscale (≈100 nm). The feedstock powder was evaluated in terms of their size distribution, external morphology, internal morphology, and initial carbide size. Two different fixtures were used in spraying to evaluate the effect of cooling rate on the wear resistance of the coatings. The microstructures of the sprayed coatings were examined using optical metallography, SEM, FESEM, TEM, XRD and chemical analysis. The coatings were evaluated in low stress abrasive wear by the ASTM G-65 Dry Sand Rubber Wheel test. Furthermore, the porosity and hardness of the coatings were evaluated. The cobalt content was found to be the predominant influence on the wear rate of the coatings. The decrease in the carbide size was not found to effect the wear rate of the coatings. Coatings sprayed on the 'hot' fixture were found to have slightly improved wear resistance as compared to coatings sprayed on the 'cold' fixture. The wear rates of the coatings were found to be a function of the WC/Co volume ratio.

  4. NK cells modulate the inflammatory response to corneal epithelial abrasion and thereby support wound healing.

    PubMed

    Liu, Qiong; Smith, C Wayne; Zhang, Wanyu; Burns, Alan R; Li, Zhijie

    2012-08-01

    Natural killer (NK) 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 classic NK cells migrated into the limbus and corneal stroma, peaking at 24 hours with an eightfold increase over baseline. Depletion of γδ T cells significantly reduced NK cell accumulation (>70%; P < 0.01); however, in neutrophil-depleted animals, NK cell influx was normal. Isolated spleen NK cells migrated to the wounded cornea, and this migration was reduced by greater than 60% (P < 0.01) by ex vivo antibody blocking of NK cell CXCR3 or CCR2. Antibody-induced depletion of NK cells significantly altered the inflammatory reaction to corneal wounding, as evidenced by a 114% increase (P < 0.01) in neutrophil influx at a time when acute inflammation is normally waning. Functional blocking of NKG2D, an activating receptor for NK cell cytotoxicity and cytokine secretion, did not inhibit NK cell immigration, but significantly increased neutrophil influx. Consistent with excessive neutrophil accumulation, NK depletion and blocking of NKG2D also inhibited corneal nerve regeneration and epithelial healing (P < 0.01). Findings of this study suggest that NK cells are actively involved in corneal healing by limiting the innate acute inflammatory reaction to corneal wounding.

  5. Abrasive wear by diesel engine coal-fuel and related particles

    SciTech Connect

    Ives, L.K.

    1994-09-01

    The purpose of the work summarized in this report was to obtain a basic understanding of the factors which are responsible for wear of the piston ring and cylinder wall surfaces in diesel engines utilizing coal-fuel. The approach included analytical studies using scanning electron microscopy and energy dispersive x-ray analyses to characterize coal-fuel and various combustion particles, and two different wear tests. The wear tests were a modified pin-on-disk test and a block-on-ring test capable of either unidirectional or reciprocating-rotational sliding. The wear tests in general were conducted with mixtures of the particles and lubricating oil. The particles studied included coal-fuel, particles resulting from the combustion of coal fuel, mineral matter extracted during the processing of coal, and several other common abrasive particle types among which quartz was the most extensively examined. The variables studied included those associated with the particles, such as particle type, size, and hardness; variables related to contact conditions and the surrounding environment; and variables related to the type and properties of the test specimen materials.

  6. [Changes in proliferation and differentiation of basal cells during wound healing of rabbit corneal epithelial abrasions].

    PubMed

    Yamada, M; Mashima, Y

    1995-01-01

    Changes in the mitotic rate and epithelial keratin expression of corneal epithelial basal cells following corneal abrasion (7.0 mm in diameter) in rabbits were studied immunohistochemically using antiproliferating cell nuclear antigen (PCNA) monoclonal antibody and anti-epithelial keratin 1 (AE1). In the non-wounded control, the mitotic rate (PCNA positive cells in the basal cell layer) was approximately 4%, and only the superficial cells were stained by AE1 monoclonal antibody. One day after wounding, migrating epithelial cells at the leading edge, which reacted to AE1, showed low mitotic activity. At days 3 and 7, the mitotic rates of basal cells of regenerating epithelium were 3 times higher than that of controls. These basal cells displayed intensive staining with AE1, while the epithelium over the unwounded cornea exhibited a normal pattern limited to superficial cells. By 14 days after injury, the mitotic rate returned to normal and all epithelial cells expressed a normal AE1 staining pattern. Theses results suggest that regeneration of corneal epithelial basal cells involves changes in keratin expression, which might correlate with changes in the mitotic rate.

  7. Toothpastes containing abrasive and chemical whitening agents: efficacy in reducing extrinsic dental staining.

    PubMed

    Soares, Cristina Neves Girao Salgado; Amaral, Flavia Lucisano Botelho do; Mesquita, Marcelo Ferraz; Franca, Fabiana Mantovani Gomes; Basting, Roberta Tarkany; Turssi, Cecilia Pedroso

    2015-01-01

    This in vitro study evaluated the efficacy of toothpastes containing abrasive and chemical whitening agents in reducing the extrinsic discoloration of dental enamel. Sixty slabs of dentin from human teeth were sealed so that only the enamel surface was exposed. The enamel surfaces were photographed for initial color assessment. Staining was performed by immersing the dental slabs in 0.2% chlorhexidine solution for 2 minutes and then in black tea for 60 minutes. This process was repeated 15 times. Photographs were taken at the end of the staining process, and the slabs were divided into 5 groups (n = 12), 3 to be brushed with toothpastes containing chemical whitening agents (2 containing phosphate salts and 1 containing phosphate salts plus hydrogen peroxide) and 2 to represent control groups (ordinary/nonwhitening toothpaste and distilled water). The dental slabs were subjected to mechanical toothbrushing with toothpaste slurry or distilled water, according to each group's specifications. After brushing, more photographs were taken for color analysis. The results showed a significant reduction in luminosity after the staining process in addition to an increase in the colors red and yellow (P < 0.001). After brushing, there was a significant increase in luminosity and a reduction in both red and yellow (P < 0.001). However, there was no observed difference between the changes in color values in dental enamel slabs brushed with whitening toothpastes and the changes found in slabs brushed with ordinary toothpaste. The whitening toothpastes did not outperform an ordinary toothpaste in the removal of extrinsic staining.

  8. Degradation of nontoxic fouling-release coatings as a result of abrasion and long-term exposure

    SciTech Connect

    Meyer, A.E.; Baier, R.E.; Forsberg, R.L.

    1995-06-01

    Previous work by this research group demonstrates that methylsilicone-based coatings having critical surface tensions between 20 and 25 mN/m allow easy mechanical detachment of zebra mussel infestations and other fouling for at least 2 years. Continuing evaluations of the coated test panels and trash racks at test sites in western New York confirm and extend the 2-year findings. Coatings which, in addition, contain elutable oils display an apparent further resistance to initial colonization by zebra mussels, but this early benefit does not carry over to the brush-removal forces required for cleaning of the once-fouled coating. Several of the elastomeric methylsilicone coatings are prone to cutting and abrasion damage, limiting their suitability for heavy-duty use and/or situations requiring periodic cleaning. Since standard tests for abrasion and wear developed for paints are not applicable to elastomeric coatings, our laboratory is using a brush abrasion test to evaluate fouling-release coatings for an increasing series of wet brushing cycles.

  9. The Optimum Production Method for Quality Improvement of Recycled Aggregates Using Sulfuric Acid and the Abrasion Method.

    PubMed

    Kim, Haseog; Park, Sangki; Kim, Hayong

    2016-07-29

    There has been increased deconstruction and demolition of reinforced concrete structures due to the aging of the structures and redevelopment of urban areas resulting in the generation of massive amounts of construction. The production volume of waste concrete is projected to increase rapidly over 100 million tons by 2020. However, due to the high cement paste content, recycled aggregates have low density and high absorption ratio. They are mostly used for land reclamation purposes with low added value instead of multiple approaches. This study was performed to determine an effective method to remove cement paste from recycled aggregates by using the abrasion and substituting the process water with acidic water. The aim of this study is to analyze the quality of the recycled fine aggregates produced by a complex method and investigate the optimum manufacturing conditions for recycled fine aggregates based on the design of experiment. The experimental parameters considered were water ratio, coarse aggregate ratio, and abrasion time and, as a result of the experiment, data concerning the properties of recycled sand were obtained. It was found that high-quality recycled fine aggregates can be obtained with 8.57 min of abrasion-crusher time and a recycled coarse aggregate ratio of over 1.5.

  10. The Optimum Production Method for Quality Improvement of Recycled Aggregates Using Sulfuric Acid and the Abrasion Method

    PubMed Central

    Kim, Haseog; Park, Sangki; Kim, Hayong

    2016-01-01

    There has been increased deconstruction and demolition of reinforced concrete structures due to the aging of the structures and redevelopment of urban areas resulting in the generation of massive amounts of construction. The production volume of waste concrete is projected to increase rapidly over 100 million tons by 2020. However, due to the high cement paste content, recycled aggregates have low density and high absorption ratio. They are mostly used for land reclamation purposes with low added value instead of multiple approaches. This study was performed to determine an effective method to remove cement paste from recycled aggregates by using the abrasion and substituting the process water with acidic water. The aim of this study is to analyze the quality of the recycled fine aggregates produced by a complex method and investigate the optimum manufacturing conditions for recycled fine aggregates based on the design of experiment. The experimental parameters considered were water ratio, coarse aggregate ratio, and abrasion time and, as a result of the experiment, data concerning the properties of recycled sand were obtained. It was found that high-quality recycled fine aggregates can be obtained with 8.57 min of abrasion-crusher time and a recycled coarse aggregate ratio of over 1.5. PMID:27483298

  11. Effect of the abrasive properties of sedges on the intestinal absorptive surface and resting metabolic rate of root voles.

    PubMed

    Wieczorek, Monika; Szafrańska, Paulina A; Labecka, Anna Maria; Lázaro, Javier; Konarzewski, Marek

    2015-01-15

    Recent studies on grasses and sedges suggest that the induction of a mechanism reducing digestibility of plant tissues in response to herbivore damage may drive rodent population cycles. This defence mechanism seems to rely on the abrasive properties of ingested plants. However, the underlying mechanism has not been demonstrated in small wild herbivores. Therefore, we carried out an experiment in which we determined the joint effect of abrasive sedge components on the histological structure of small intestine as well as resting metabolic rate (RMR) of the root vole (Microtus oeconomus). Histological examination revealed that voles fed with a sedge-dominated diet had shorter villi composed from narrower enterocytes in duodenum, jejunum and ileum. Reduction in the height of villi decreased along the small intestine. Activity of the mucus secretion increased along the small intestine and was significantly higher in the ileum. The intestinal abrasion exceeded the compensatory capabilities of voles, which responded to a sedge-dominated diet by a reduction of body mass and a concomitant decrease in whole body RMR. These results explain the inverse association between body mass and the probability of winter survival observed in voles inhabiting homogenous sedge wetlands.

  12. Trajectories and energy transfer of saltating particles onto rock surfaces : application to abrasion and ventifact formation on Earth and Mars

    NASA Technical Reports Server (NTRS)

    Bridges, Nathan T.; Phoreman, James; White, Bruce R.; Greeley, Ronald; Eddlemon, Eric E.; Wilson, Gregory R.; Meyer, Christine J.

    2005-01-01

    The interaction between saltating sand grains and rock surfaces is assessed to gauge relative abrasion potential as a function of rock shape, wind speed, grain size, and planetary environment. Many kinetic energy height profiles for impacts exhibit a distinctive increase, or kink, a few centimeters above the surface, consistent with previous field, wind tunnel, and theoretical investigations. The height of the kink observed in natural and wind tunnel settings is greater than predictions by a factor of 2 or more, probably because of enhanced bouncing off hard ground surfaces. Rebounded grains increase the effective flux and relative kinetic energy for intermediate slope angles. Whether abrasion occurs, as opposed to simple grain impact with little or no mass lost from the rock, depends on whether the grain kinetic energy (EG) exceeds a critical value (EC), as well as the flux of grains with energies above EC. The magnitude of abrasion and the shape change of the rock over time depends on this flux and the value of EG > EC. Considering the potential range of particle sizes and wind speeds, the predicted kinetic energies of saltating sand hitting rocks overlap on Earth and Mars. However, when limited to the most likely grain sizes and threshold conditions, our results agree with previous work and show that kinetic energies are about an order of magnitude greater on Mars.

  13. Photoresist-free patterning by mechanical abrasion of water-soluble lift-off resists and bare substrates: toward green fabrication of transparent electrodes.

    PubMed

    Printz, Adam D; Chan, Esther; Liong, Celine; Martinez, René S; Lipomi, Darren J

    2013-01-01

    This paper describes the fabrication of transparent electrodes based on grids of copper microwires using a non-photolithographic process. The process--"abrasion lithography"--takes two forms. In the first implementation (Method I), a water-soluble commodity polymer film is abraded with a sharp tool, coated with a conductive film, and developed by immersion in water. Water dissolves the polymer film and lifts off the conductive film in the unabraded areas. In the second implementation (Method II), the substrate is abraded directly by scratching with a sharp tool (i.e., no polymer film necessary). The abraded regions of the substrate are recessed and roughened. Following deposition of a conductive film, the lower profile and roughened topography in the abraded regions prevents mechanical exfoliation of the conductive film using adhesive tape, and thus the conductive film remains only where the substrate is scratched. As an application, conductive grids exhibit average sheet resistances of 17 Ω sq(-1) and transparencies of 86% are fabricated and used as the anode in organic photovoltaic cells in concert with the conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Compared to devices in which PEDOT:PSS alone serves as an anode, devices comprising grids of copper/nickel microwires and PEDOT:PSS exhibit lowered series resistance, which manifests in greater fill factor and power conversion efficiency. This simple method of forming micropatterns could find use in applications where cost and environmental impact should be minimized, especially as a potential replacement for the transparent electrode indium tin oxide (ITO) in thin-film electronics over large areas (i.e., solar cells) or as a method of rapid prototyping for laboratory-scale devices.

  14. Photoresist-Free Patterning by Mechanical Abrasion of Water-Soluble Lift-Off Resists and Bare Substrates: Toward Green Fabrication of Transparent Electrodes

    PubMed Central

    Printz, Adam D.; Chan, Esther; Liong, Celine; Martinez, René S.; Lipomi, Darren J.

    2013-01-01

    This paper describes the fabrication of transparent electrodes based on grids of copper microwires using a non-photolithographic process. The process—“abrasion lithography”—takes two forms. In the first implementation (Method I), a water-soluble commodity polymer film is abraded with a sharp tool, coated with a conductive film, and developed by immersion in water. Water dissolves the polymer film and lifts off the conductive film in the unabraded areas. In the second implementation (Method II), the substrate is abraded directly by scratching with a sharp tool (i.e., no polymer film necessary). The abraded regions of the substrate are recessed and roughened. Following deposition of a conductive film, the lower profile and roughened topography in the abraded regions prevents mechanical exfoliation of the conductive film using adhesive tape, and thus the conductive film remains only where the substrate is scratched. As an application, conductive grids exhibit average sheet resistances of 17 Ω sq–1 and transparencies of 86% are fabricated and used as the anode in organic photovoltaic cells in concert with the conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Compared to devices in which PEDOT:PSS alone serves as an anode, devices comprising grids of copper/nickel microwires and PEDOT:PSS exhibit lowered series resistance, which manifests in greater fill factor and power conversion efficiency. This simple method of forming micropatterns could find use in applications where cost and environmental impact should be minimized, especially as a potential replacement for the transparent electrode indium tin oxide (ITO) in thin-film electronics over large areas (i.e., solar cells) or as a method of rapid prototyping for laboratory-scale devices. PMID:24358321

  15. The development of an in vitro test method for predicting the abrasion resistance of textile and metal components of endovascular stent grafts.

    PubMed

    Yao, Tong; Choules, Brian D; Rust, Jon P; King, Martin W

    2014-04-01

    Implantable endovascular stent grafts have become a frequent option for the treatment of abdominal and thoracic aneurysms. Given that such devices are permanent implants, the question of long-term biostability needs to be addressed. This article describes the development of an in vitro stent graft abrasion test method between the graft fabric and metal stent of an endovascular device. Three endpoints were established to determine the abrasion resistance between the fabric and stent surfaces after a predetermined number of abrasion cycles. During initial testing, two types of graft fabric materials, multifilament woven polyester fabric and monofilament woven polyester fabric, and two types of stent materials, laser cut nitinol stents and regular nitinol stent wire, were evaluated under dry and wet conditions. The results have shown that this test method is viable for testing the relative abrasion resistance of the components of endovascular stent grafts. The abrasion resistance of both fabrics was lower in a wet environment compared to being tested dry. Additionally, the multifilament polyester fabric had better abrasion resistance than the monofilament polyester fabric. The laser cut nitinol stent was more aggressive in creating holes and breaking yarns, while the regular nitinol stent wire caused a greater loss in fabric strength.

  16. Robot based deposition of WC-Co HVOF coatings on HSS cutting tools as a substitution for solid cemented carbide cutting tools

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Schaak, C.; Biermann, D.; Aßmuth, R.; Goeke, S.

    2017-03-01

    Cemented carbide (hard metal) cutting tools are the first choice to machine hard materials or to conduct high performance cutting processes. Main advantages of cemented carbide cutting tools are their high wear resistance (hardness) and good high temperature strength. In contrast, cemented carbide cutting tools are characterized by a low toughness and generate higher production costs, especially due to limited resources. Usually, cemented carbide cutting tools are produced by means of powder metallurgical processes. Compared to conventional manufacturing routes, these processes are more expensive and only a limited number of geometries can be realized. Furthermore, post-processing and preparing the cutting edges in order to achieve high performance tools is often required. In the present paper, an alternative method to substitute solid cemented carbide cutting tools is presented. Cutting tools made of conventional high speed steels (HSS) were coated with thick WC-Co (88/12) layers by means of thermal spraying (HVOF). The challenge is to obtain a dense, homogenous, and near-net-shape coating on the flanks and the cutting edge. For this purpose, different coating strategies were realized using an industrial robot. The coating properties were subsequently investigated. After this initial step, the surfaces of the cutting tools were ground and selected cutting edges were prepared by means of wet abrasive jet machining to achieve a smooth and round micro shape. Machining tests were conducted with these coated, ground and prepared cutting tools. The occurring wear phenomena were analyzed and compared to conventional HSS cutting tools. Overall, the results of the experiments proved that the coating withstands mechanical stresses during machining. In the conducted experiments, the coated cutting tools showed less wear than conventional HSS cutting tools. With respect to the initial wear resistance, additional benefits can be obtained by preparing the cutting edge by means

  17. Incidence of lameness and abrasions in piglets in identical farrowing pens with four different types of floor

    PubMed Central

    Zoric, Mate; Nilsson, Ebba; Lundeheim, Nils; Wallgren, Per

    2009-01-01

    Background Lameness in piglets is a major animal welfare issue. Floor abrasiveness is a common cause of superficial injury in piglets in farrowing pens. The abrasion achieved may act as a gate for infections, which in turn may induce development of infectious arthritis. In this study, the influence of improvements of the floor quality and of increased ratios of straw in identical farrowing pens was measured. Methods The study was carried out at a herd with four identical farrowing units with solid concrete floor bedded with 1 kg chopped straw per sow and 1 hg per piglet and day. Nothing was changed in the management of the four identical farrowing units, but four experimental groups were created: Group I – control, Group II – the amount of bedding was doubled. The surface of the floor was repaired in two units, Group III – Piglet Floor®, Flowcrete Sweden AB, Perstorp, Sweden and Group IV – Thorocrete SL®, Växa Halland, Sweden. Three farrowing batches were studies in each unit. In total, 93 litters (1,073 piglets) were examined for foot and skin lesions until the age of 3 weeks. The occurrence of lameness was registered until weaning at an average age of 4.5 weeks. Twenty seven lame piglets were culled instead of medicinally treated and subjected to necropsy including histopathological and microbiological examinations. Isolates of streptococci, staphylococci and E. coli were tested with respect to antimicrobial resistance. Results Piglet born on the repaired floors had the lowest prevalences of abrasions at carpus. Also the doubled straw ration decreased the abrasions. Skin lesions at carpus decreased significantly in magnitude in all four systems from day 10. At day 3, the sole bruising scores of the control unit were greater than the other three units (p < 0.001). At day 10 and 17, sole bruising was less common in the units with repaired floors than in the control group and the group with doubled straw ration. In total 41 piglets were diagnosed as lame

  18. Stability against brushing abrasion and the erosion-protective effect of different fluoride compounds.

    PubMed

    Wiegand, A; Schneider, S; Sener, B; Roos, M; Attin, T

    2014-01-01

    This study aimed to analyse the impact of brushing on the protective effect of different fluoride solutions on enamel and dentin erosion. Bovine enamel and dentin specimens were rinsed once with TiF4, AmF, SnF2 (0.5 M F, 2 min) or water (control). Specimens were either left unbrushed or brushed with 10, 20, 50, 100 or 500 brushing strokes in an automatic brushing machine (2 N, non-fluoridated toothpaste slurry). Ten specimens per group were eroded with hydrochloric acid (HCl) (pH 2.3) for 60 s, and calcium release into the acid was determined by atomic absorption spectroscopy. Additionally, enamel and dentin surfaces were analysed by X-ray energy-dispersive spectroscopy (EDS) (n = 6/group) and scanning electron microscopy (SEM) (n = 2/group) before brushing and after 500 brushing strokes. Statistical analysis (p < 0.05) was performed by three- and one-way ANOVA (calcium release) or repeated measures ANOVA (EDS). TiF4, AmF and SnF2 reduced the erosive calcium loss in unbrushed specimens to 58-67% (enamel) and 23-31% (dentin) of control. Calcium release increased with increasing brushing strokes prior to erosion and amounted to 70-88% (enamel) and 45-78% (dentin) of control after 500 brushing strokes. Brushing reduced the surface concentration of fluoride (AmF), tin (SnF2) and titanium (TiF4). SEM revealed that surface precipitates were affected by long-term brushing. Brushing reduced the protective potential of TiF4, AmF and SnF2 solutions. However, considering a small number of brushing strokes, the protective effect of fluoride solutions is only slightly affected by brushing abrasion.

  19. Medial abrasion syndrome: a neglected cause of knee pain in middle and old age.

    PubMed

    Lyu, Shaw-Ruey; Lee, Ching-Chih; Hsu, Chia-Chen

    2015-04-01

    Knee pain is a prevailing health problem of middle and old age. Medial plica-related medial abrasion syndrome (MAS), although a well-known cause of knee pain in younger individuals, has rarely been investigated in older individuals. This prospective study was conducted to investigate the prevalence and clinical manifestations of this syndrome as a cause of knee pain in middle and old age. The outcomes of arthroscopic treatment for this syndrome were also evaluated.A total of 232 knees of 169 patients >40 years of age (41-82, median: 63 years old) suffering from chronic knee pain were analyzed. The clinical diagnosis, predisposing factors, presenting symptoms, and physical signs were investigated. The sensitivity and specificity of each parameter of the clinical presentation for the diagnosis of MAS were evaluated after confirmation by arthroscopy. For patients with MAS, the roentgenographic and arthroscopic manifestations were investigated, and arthroscopic medial release (AMR) was performed. The outcomes were evaluated by the changes in the pain domain of the Knee Society scoring system and by patient satisfaction. The prevalence of medial plica was 95%, and osteoarthritis (OA) was the most common clinical diagnosis. Symptoms of pain and crepitus in motion and local tenderness during physical examination were the most sensitive parameters for the diagnosis. A history of a single knee injury combined with local tenderness and a palpable band found during physical examination were the most specific parameters for the diagnosis. The majority of patients suffering from this syndrome were successfully treated using AMR, yielding a satisfaction rate of 85.5% after a minimum of 3 years.MAS is a common cause of knee pain in middle and old age and can be effectively treated by AMR. Its concomitance with OA warrants further investigation.

  20. Preventive effect of toothpastes with MMP inhibitors on human dentine erosion and abrasion in vitro

    PubMed Central

    Hannas, Angelica Reis; Kato, Melissa Thiemi; Cardoso, Cristiane de Almeida Baldini; Magalhães, Ana Carolina; Pereira, José Carlos; Tjäderhane, Leo; Buzalaf, Marília Afonso Rabelo

    2016-01-01

    ABSTRACT The use of gels and mouthrinses with MMP inhibitors (chlorhexidine, and green tea extract) was shown to prevent erosive wear. The aim of this study was to analyze the protective effect of toothpastes containing MMP inhibitors on dentine loss induced by erosion in vitro. Material and Methods Five groups each containing 12 specimens of human root dentine were prepared. The specimens were subjected to 1 min erosion by immersion in a cola drink, 4 times a day, for 5 d. Each day, after the first and last erosive challenges, the specimens were brushed for 15 s with a slurry of dentifrice and water (1:3) containing placebo, 1,100 ppm fluoride, 0.61% green tea extract, 0.12% chlorhexidine or 0.004% chlorhexidine (commercial toothpaste). Between the acid challenges, the specimens were stored in artificial saliva with remineralizing potential until the next treatment. Dentine loss was determined using profilometry. Data were analyzed using one-way ANOVA after log transform (p<0.05). Results The mean wear values (μm) were as follows: placebo 1.83±0.53; 0.61% green tea extract 1.00±0.21; fluoride 1.27±0.43; 0.12% chlorhexidine 1.19±0.30; and 0.004% chlorhexidine 1.22±0.46. There was a significant difference in wear between placebo and all the treatment toothpastes, which did not differ from each other. Conclusion The results suggest that toothpastes containing MMP inhibitors are as effective as those based on NaF in preventing dentine erosion and abrasion. PMID:27008258