Non-covalently functionalized carbon nanostructures for synthesizing carbon-based hybrid nanomaterials.

PubMed

Li, Haiqing; Song, Sing I; Song, Ga Young; Kim, Il

2014-02-01

Carbon nanostructures (CNSs) such as carbon nanotubes, graphene sheets, and nanodiamonds provide an important type of substrate for constructing a variety of hybrid nanomaterials. However, their intrinsic chemistry-inert surfaces make it indispensable to pre-functionalize them prior to immobilizing additional components onto their surfaces. Currently developed strategies for functionalizing CNSs include covalent and non-covalent approaches. Conventional covalent treatments often damage the structure integrity of carbon surfaces and adversely affect their physical properties. In contrast, the non-covalent approach offers a non-destructive way to modify CNSs with desired functional surfaces, while reserving their intrinsic properties. Thus far, a number of surface modifiers including aromatic compounds, small-molecular surfactants, amphiphilic polymers, and biomacromolecules have been developed to non-covalently functionalize CNS surfaces. Mediated by these surface modifiers, various functional components such as organic species and inorganic nanoparticles were further decorated onto their surfaces, resulting in versatile carbon-based hybrid nanomaterials with broad applications in chemical engineering and biomedical areas. In this review, the recent advances in the generation of such hybrid nanostructures based on non-covalently functionalized CNSs will be reviewed.

Optical monitoring of proteins at solid interfaces

NASA Astrophysics Data System (ADS)

Dunne, G.; McDonnell, L.; Miller, R.; McMillan, N. D.; O'Rourke, B.; Mitchell, C. I.

2005-06-01

The adsorption properties of polymers are of great importance for implant studies. A better understanding of these properties can lead to improved implant materials. In this study the surface energy of different polymers was derived from contact angle measurements taken using profile analysis tensiometry (PAT) of sessile drops of water. The contact angles were measured for advancing and receding water drops on polished polymer surfaces and also on polymer surfaces modified by adsorbing protein to the surface prior to analysis of the sessile drop. The protein used was bovine serum albumin (BSA) and the surfaces were poly-methylmethacrylate (PMMA), poly-ether-ether-ketone (PEEK) and stainless steel. The polymer surfaces were also studied using atomic force microscopy (AFM). Images of the surfaces were taken in different states: rough, smooth and with albumin adsorbed. As a method to identify the proteins on the surface easier, anti-albumin antibodies with 30nm nano gold particles attached were adsorbed to the albumin on the surfaces. Using nano gold particles made the imaging more straightforward and thus made identification of the protein on the surface easier. The results from this work show the differing hydrophobicities of polymer surfaces under different conditions and a new nanotechnological method of protein identification.

Physical properties of the martian surface from the viking 1 lander: preliminary results.

PubMed

Shorthill, R W; Hutton, R E; Moore, H J; Scott, R F; Spitzer, C R

1976-08-27

The purpose of the physical properties experiment is to determine the characteristics of the martian "soil" based on the use of the Viking lander imaging system, the surface sampler, and engineering sensors. Viking 1 lander made physical contact with the surface of Mars at 11:53:07.1 hours on 20 July 1976 G.M.T. Twenty-five seconds later a high-resolution image sequence of the area around a footpad was started which contained the first information about surface conditions on Mars. The next image is a survey of the martian landscape in front of the lander, including a view of the top support of two of the landing legs. Each leg has a stroke gauge which extends from the top of the leg support an amount equal to the crushing experienced by the shock absorbers during touchdown. Subsequent images provided views of all three stroke gauges which, together with the knowledge of the impact velocity, allow determination of "soil" properties. In the images there is evidence of surface erosion from the engines. Several laboratory tests were carried out prior to the mission with a descent engine to determine what surface alterations might occur during a Mars landing. On sol 2 the shroud, which protected the surface sampler collector head from biological contamination, was ejected onto the surface. Later a cylindrical pin which dropped from the boom housing of the surface sampler during the modified unlatching sequence produced a crater (the second Mars penetrometer experiment). These two experiments provided further insight into the physical properties of the martian surface.

Physical properties of the martian surface from the Viking 1 lander: preliminary results

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

Shorthill, R.W.; Hutton, R.E.; Moore, H.J. II

1976-08-27

The purpose of the physical properties experiment is to determine the characteristics of the martian ''soil'' based on the use of the Viking lander imaging system, the surface sampler, and engineering sensors. Viking 1 lander made physical contact with the surface of Mars at 11:53:07.1 hours on 20 July 1976 G.M.T. Twenty-five seconds later a high-resolution image sequence of the area around a footpad was started which contained the first information about surface conditions on Mars. The next image is a survey of the martian landscape in front of the lander, including a view of the top support of twomore » of the landing legs. Each leg has a stroke gauge which extends from the top of the leg support an amount equal to the crushing experienced by the shock absorbers during touchdown. Subsequent images provided views of all three stroke gauges which, together with the knowledge of the impact velocity, allow determination of ''soil'' properties. In the images there is evidence of surface erosion from the engines. Several laboratory tests were carried out prior to the mission with a descent engine to determine what surface alterations might occur during a Mars landing. On sol 2 the shroud, which protected the surface sampler collector head from biological contamination, was ejected onto the surface. Later a cylindrical pin which dropped from the boom housing of the surface sampler during the modified unlatching sequence produced a crater (the second Mars penetrometer experiment). These two experiments provided further insight into the physical properties of the martian surface.« less

Effect of plasma pretreatment on adhesion and mechanical properties of UV-curable coatings on plastics

NASA Astrophysics Data System (ADS)

Gururaj, T.; Subasri, R.; Raju, K. R. C. Soma; Padmanabham, G.

2011-02-01

An attempt was made to study the effect of plasma surface activation on the adhesion of UV-curable sol-gel coatings on polycarbonate (PC) and polymethylmethacrylate (PMMA) substrates. The sol was synthesized by the hydrolysis and condensation of a UV-curable silane in combination with Zr-n-propoxide. Coatings deposited by dip coating were cured using UV-radiation followed by thermal curing between 80 °C and 130 °C. The effect of plasma surface treatment on the wettability of the polymer surface prior to coating deposition was followed up by measuring the water contact angle. The water contact angle on the surface of as-cleaned substrates was 80° ± 2° and that after plasma treatment was 43° ± 1° and 50° ± 2° for PC and PMMA respectively. Adhesion as well as mechanical properties like scratch resistance and taber abrasion resistance were evaluated for coatings deposited over plasma treated and untreated surfaces.

Local functional descriptors for surface comparison based binding prediction

PubMed Central

2012-01-01

Background Molecular recognition in proteins occurs due to appropriate arrangements of physical, chemical, and geometric properties of an atomic surface. Similar surface regions should create similar binding interfaces. Effective methods for comparing surface regions can be used in identifying similar regions, and to predict interactions without regard to the underlying structural scaffold that creates the surface. Results We present a new descriptor for protein functional surfaces and algorithms for using these descriptors to compare protein surface regions to identify ligand binding interfaces. Our approach uses descriptors of local regions of the surface, and assembles collections of matches to compare larger regions. Our approach uses a variety of physical, chemical, and geometric properties, adaptively weighting these properties as appropriate for different regions of the interface. Our approach builds a classifier based on a training corpus of examples of binding sites of the target ligand. The constructed classifiers can be applied to a query protein providing a probability for each position on the protein that the position is part of a binding interface. We demonstrate the effectiveness of the approach on a number of benchmarks, demonstrating performance that is comparable to the state-of-the-art, with an approach with more generality than these prior methods. Conclusions Local functional descriptors offer a new method for protein surface comparison that is sufficiently flexible to serve in a variety of applications. PMID:23176080

Properties of M40J Carbon/PMR-II-50 Composites Fabricated with Desized and Surface Treated Fibers. Characterization of M40J Desized and Finished Fibers

NASA Technical Reports Server (NTRS)

Allred, Ronald E.; Gosau, Jan M.; Shin, E. Eugene; McCorkle, Linda S.; Sutter, James K.; OMalley, Michelle; Gray, Hugh R. (Technical Monitor)

2002-01-01

To increase performance and durability of high temperature composites for potential rocket engine components, it is necessary to optimize wetting and interfacial bonding between high modulus carbon fibers and high temperature polyimide resins. It has been previously demonstrated that the electro-oxidative shear treatments used by fiber manufacturers are not effective on higher modulus fibers that have fewer edge and defect sites in the surface crystallites. In addition, sizings commercially supplied on most carbon fibers are not compatible with polyimides. This study was an extension of prior work characterizing the surface chemistry and energy of high modulus carbon fibers (M40J and M60J, Torray) with typical fluorinated polyimide resins, such as PMR-II-50. A continuous desizing system which utilizes environmentally friendly chemical- mechanical processes was developed for tow level fiber and the processes were optimized based on weight loss behavior, surface elemental composition (XPS) and morphology (FE-SEM) analyses, and residual tow strength of the fiber, and the similar approaches have been applied on carbon fabrics. Both desized and further treated with a reactive finish were investigated for the composite reinforcement. The effects of desizing and/or subsequent surface retreatment on carbon fiber on composite properties and performance including fiber-matrix interfacial mechanical properties, thermal properties and blistering onset behavior will be discussed in this presentation.

Synthesis methods of gold nanoparticles for Localized Surface Plasmon Resonance (LSPR) sensor applications

NASA Astrophysics Data System (ADS)

Diyanah Samsuri, Nurul; Maisarah Mukhtar, Wan; Rashid, Affa Rozana Abdul; Dasuki, Karsono Ahmad; Awangku Yussuf, Awangku Abdul Rahman Hj.

2017-11-01

Gold nanoparticles (GNPs) have been known as an excellent characteristic for Local Surface Plasmon Resonance (LSPR) sensors due to their sensitive spectral response to the local environment of the nanoparticle surface and ease of monitoring the light signal due to their strong scattering or absorption. Prior the technologies, GNPs based LSPR has been commercialized and have become a central tool for characterizing and quantifying in various field. In this review, we presented a brief introduction on the history of surface plasmon, the theory behind the surface plasmon resonance (SPR) and the principles of LSPR. We also reported on the synthetization as well of the properties of the GNPs and the applications in current LSPR sensors.

Unusual Stiffening and Elastic Response of Polyisobutylene Nanometric Thin Films

NASA Astrophysics Data System (ADS)

Yoon, Heedong; Wigham, Caleb; McKenna, Gregory

The TTU bubble inflation technique was used to study the elastic response and unusual stiffening behavior of nanometirc polyisobutylene (PIB) films. Mechanical properties and surface tension of PIB films were measured through the strain-stress response for film thicknesses ranging from 13 nm to 126 nm. The tests were performed at room temperature, far above the glass transition temperature of PIB. It is found that the stiffening increases with decreasing film thickness, while the surface tension is independent of the film thickness. Similar to the prior bubble inflation measurements in polymeric thin films, the thickness dependence of the stiffening followed a power law behavior in this case of Ds h1.5. These results are consistent with the Ngai et al proposition that rubbery stiffening is related to the separation of the α relaxation and Rouse modes. In addition, we compare stiffening index (S) with fragility (m) based on our prior observation that the S follows a linear behavior with dynamic m. Unlike other polymeric materials seen in prior bubble inflation measurements, the S of PIB does not follow the linear behavior with m.

Electrical properties of metal/Al2O3/In0.53Ga0.47As capacitors grown on InP

NASA Astrophysics Data System (ADS)

Ferrandis, Philippe; Billaud, Mathilde; Duvernay, Julien; Martin, Mickael; Arnoult, Alexandre; Grampeix, Helen; Cassé, Mikael; Boutry, Hervé; Baron, Thierry; Vinet, Maud; Reimbold, Gilles

2018-04-01

To overcome the Fermi-level pinning in III-V metal-oxide-semiconductor capacitors, attention is usually focused on the choice of dielectric and surface chemical treatments prior to oxide deposition. In this work, we examined the influence of the III-V material surface cleaning and the semiconductor growth technique on the electrical properties of metal/Al2O3/In0.53Ga0.47As capacitors grown on InP(100) substrates. By means of the capacitance-voltage measurements, we demonstrated that samples do not have the same total oxide charge density depending on the cleaning solution used [(NH4)2S or NH4OH] prior to oxide deposition. The determination of the interface trap density revealed that a Fermi-level pinning occurs for samples grown by metalorganic chemical vapor deposition but not for similar samples grown by molecular beam epitaxy. Deep level transient spectroscopy analysis explained the Fermi-level pinning by an additional signal for samples grown by metalorganic chemical vapor deposition, attributed to the tunneling effect of carriers trapped in oxide toward interface states. This work emphasizes that the choice of appropriate oxide and cleaning treatment is not enough to prevent a Fermi-level pinning in III-V metal-oxide-semiconductor capacitors. The semiconductor growth technique needs to be taken into account because it impacts the trapping properties of the oxide.

Plasma carburizing with surface micro-melting

NASA Astrophysics Data System (ADS)

Balanovsky, A. E.; Grechneva, M. V.; Van Huy, Vu; Ponomarev, B. B.

2018-03-01

This paper presents carburizing the surface of 20 low carbon steel using electric arc and graphite prior. A carbon black solution was prepared with graphite powder and sodium silicate in water. A detailed analysis of the phase structure and the distribution profile of the sample hardness after plasma treatment were given. The hardened layer consists of three different zones: 1 – the cemented layer (thin white zone) on the surface, 2 – heat-affected zone (darkly etching structure), 3 – the base metal. The experimental result shows that the various microstructures and micro-hardness profiles were produced depending on the type of graphite coating (percentage of liquid glass) and processing parameters. The experiment proved that the optimum content of liquid glass in graphite coating is 50–87.5%. If the amount of liquid glass is less than 50%, adhesion to metal is insufficient. If liquid glass content is more than 87.5%, carburization of a metal surface does not occur. A mixture of the eutectic lamellar structure, martensite and austenite was obtained by using graphite prior with 67% sodium silicate and the levels of the hardness layer increased to around 1000 HV. The thickness of the cemented layer formed on the surface was around 200 μm. It is hoped that this plasma surface carburizing treatment could improve the tribological resistance properties.

Anti-icing properties of superhydrophobic ZnO/PDMS composite coating

NASA Astrophysics Data System (ADS)

Yang, Chao; Wang, Fajun; Li, Wen; Ou, Junfei; Li, Changquan; Amirfazli, Alidad

2016-01-01

We present the excellent anti-icing performance for a superhydrophobic coating surface based on ZnO/polydimethylsiloxane (ZnO/PDMS) composite. The superhydrophobic ZnO/PDMS coating surface was prepared by a facile solution mixing, drop coating, room-temperature curing and surface abrading procedure. The superhydrophobic ZnO/PDMS composite coating possesses a water contact angle of 159.5° and a water sliding angle of 8.3° at room temperature (5 °C). The anti-icing properties of the superhydrophobic coating were investigated by continuously dropping cold-water droplets (about 0 °C) onto the pre-cooled surface using a home-made apparatus. The sample was placed at different tilting angle (0° and 10°) and pre-cooled to various temperatures (-5, -10 and -15 °C) prior to measure. The pure Al surface was also studied for comparison. It was found that icing accretion on the surface could be reduced apparently because the water droplets merged together and slid away from the superhydrophobic surface at all of the measuring temperatures when the surface is horizontally placed. In addition, water droplet slid away completely from the superhydrophobic surface at -5 and -10 °C when the surface is tilted at 10°, which demonstrates its excellent anti-icing properties at these temperatures. When the temperature decreased to -15 °C, though ice accretion on the tilted superhydrophobic coating surface could not be avoided absolutely, the amount of ice formed on the surface is very small, which indicated that the coating surface with superhydrophobicity could significantly reduce ice accumulation on the surface at very low temperature (-15 °C). Importantly, the sample is also stable against repeated icing/deicing cycles. More meaningfully, once the superhydrophobic surface is damaged, it can be repaired easily and rapidly.

Oxygen Plasma Modification of Poss-Coated Kapton(Registered TradeMark) HN Films

NASA Technical Reports Server (NTRS)

Wohl, C. J.; Belcher, M. A.; Ghose, S.; Connell, J. W.

2008-01-01

The surface energy of a material depends on both surface composition and topographic features. In an effort to modify the surface topography of Kapton(Registered TradeMark) HN film, organic solutions of a polyhedral oligomeric silsesquioxane, octakis(dimethylsilyloxy)silsesquioxane (POSS), were spray-coated onto the Kapton(Registered TradeMark) HN surface. Prior to POSS application, the Kapton(Registered TradeMark) HN film was activated by exposure to radio frequency (RF)-generated oxygen plasma. After POSS deposition and solvent evaporation, the films were exposed to various durations of RF-generated oxygen plasma to create a topographically rich surface. The modified films were characterized using optical microscopy, attenuated total reflection infrared (ATR-IR) spectroscopy, and high-resolution scanning electron microscopy (HRSEM). The physical properties of the modified films will be presented.

Mercury Underpotential Deposition to Determine Iridium and Iridium Oxide Electrochemical Surface Areas

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

Alia, Shaun M.; Hurst, Katherine E.; Kocha, Shyam S.

Determining the surface areas of electrocatalysts is critical for separating the key properties of area-specific activity and electrochemical surface area from mass activity. Hydrogen underpotential deposition and carbon monoxide oxidation are typically used to evaluate iridium (Ir) surface areas, but are ineffective on oxides and can be sensitive to surface oxides formed on Ir metals. Mercury underpotential deposition is presented in this study as an alternative, able to produce reasonable surface areas on Ir and Ir oxide nanoparticles, and able to produce similar surface areas prior to and following characterization in oxygen evolution. Reliable electrochemical surface areas allow for comparativemore » studies of different catalyst types and the characterization of advanced oxygen evolution catalysts. Lastly, they also enable the study of catalyst degradation in durability testing, both areas of increasing importance within electrolysis and electrocatalysis.« less

Mercury Underpotential Deposition to Determine Iridium and Iridium Oxide Electrochemical Surface Areas

DOE PAGES

Alia, Shaun M.; Hurst, Katherine E.; Kocha, Shyam S.; ...

2016-06-02

Determining the surface areas of electrocatalysts is critical for separating the key properties of area-specific activity and electrochemical surface area from mass activity. Hydrogen underpotential deposition and carbon monoxide oxidation are typically used to evaluate iridium (Ir) surface areas, but are ineffective on oxides and can be sensitive to surface oxides formed on Ir metals. Mercury underpotential deposition is presented in this study as an alternative, able to produce reasonable surface areas on Ir and Ir oxide nanoparticles, and able to produce similar surface areas prior to and following characterization in oxygen evolution. Reliable electrochemical surface areas allow for comparativemore » studies of different catalyst types and the characterization of advanced oxygen evolution catalysts. Lastly, they also enable the study of catalyst degradation in durability testing, both areas of increasing importance within electrolysis and electrocatalysis.« less

Main Geomagnetic Field Models from Oersted and Magsat Data Via a Rigorous General Inverse Theory with Error Bounds

NASA Technical Reports Server (NTRS)

Backus, George E.

1999-01-01

The purpose of the grant was to study how prior information about the geomagnetic field can be used to interpret surface and satellite magnetic measurements, to generate quantitative descriptions of prior information that might be so used, and to use this prior information to obtain from satellite data a model of the core field with statistically justifiable error estimates. The need for prior information in geophysical inversion has long been recognized. Data sets are finite, and faithful descriptions of aspects of the earth almost always require infinite-dimensional model spaces. By themselves, the data can confine the correct earth model only to an infinite-dimensional subset of the model space. Earth properties other than direct functions of the observed data cannot be estimated from those data without prior information about the earth. Prior information is based on what the observer already knows before the data become available. Such information can be "hard" or "soft". Hard information is a belief that the real earth must lie in some known region of model space. For example, the total ohmic dissipation in the core is probably less that the total observed geothermal heat flow out of the earth's surface. (In principle, ohmic heat in the core can be recaptured to help drive the dynamo, but this effect is probably small.) "Soft" information is a probability distribution on the model space, a distribution that the observer accepts as a quantitative description of her/his beliefs about the earth. The probability distribution can be a subjective prior in the sense of Bayes or the objective result of a statistical study of previous data or relevant theories.

Surface acoustic wave actuated cell sorting (SAWACS).

PubMed

Franke, T; Braunmüller, S; Schmid, L; Wixforth, A; Weitz, D A

2010-03-21

We describe a novel microfluidic cell sorter which operates in continuous flow at high sorting rates. The device is based on a surface acoustic wave cell-sorting scheme and combines many advantages of fluorescence activated cell sorting (FACS) and fluorescence activated droplet sorting (FADS) in microfluidic channels. It is fully integrated on a PDMS device, and allows fast electronic control of cell diversion. We direct cells by acoustic streaming excited by a surface acoustic wave which deflects the fluid independently of the contrast in material properties of deflected objects and the continuous phase; thus the device underlying principle works without additional enhancement of the sorting by prior labelling of the cells with responsive markers such as magnetic or polarizable beads. Single cells are sorted directly from bulk media at rates as fast as several kHz without prior encapsulation into liquid droplet compartments as in traditional FACS. We have successfully directed HaCaT cells (human keratinocytes), fibroblasts from mice and MV3 melanoma cells. The low shear forces of this sorting method ensure that cells survive after sorting.

Integrating volcanic gas monitoring with other geophysical networks in Iceland

NASA Astrophysics Data System (ADS)

Pfeffer, Melissa A.

2017-04-01

The Icelandic Meteorological Office/Icelandic Volcano Observatory is rapidly developing and improving the use of gas measurements as a tool for pre- and syn-eruptive monitoring within Iceland. Observations of deformation, seismicity, hydrological properties, and gas emissions, united within an integrated approach, can provide improved understanding of subsurface magma movements. This is critical to evaluate signals prior to and during volcanic eruptions, issue timely eruption warnings, forecast eruption behavior, and assess volcanic hazards. Gas measurements in Iceland need to be processed to account for the high degree of gas composition alteration due to interaction with external water and rocks. Deeply-sourced magmatic gases undergo reactions and modifications as they move to the surface that exercise a strong control on the composition of surface emissions. These modifications are particularly strong at ice-capped volcanoes where most surface gases are dissolved in glacial meltwater. Models are used to project backwards from surface gas measurements to what the magmatic gas composition was prior to upward migration. After the pristine magma gas composition has been determined, it is used together with fluid compositions measured in mineral hosted melt inclusions to calculate magmatic properties to understand magma storage and migration and to discern if there have been changes in the volcanic system. The properties derived from surface gas measurements can be used as input to models interpreting deformation and seismic observations, and can be used as an additional, independent observation when interpreting hydrological and seismic changes. An integrated approach aids with determining whether observed hydro/geological changes can be due to the presence of shallow magma. Constraints on parameters such as magma gas content, viscosity and compressibility can be provided by the approach described above, which can be utilized syn-eruptively to help explain differences between erupted volumes and the inferred volume change of magma chambers. We will describe two recent examples of integrated monitoring in Iceland 1) syn-eruptive gas and deformation measurements used to simulate the subsurface properties of the magma from the 2014-2015 eruption of Bárðarbunga and 2) hydrological, seismic, and gas measurements made during the 2014 Sólheimajökull jökulhlaup used to discriminate between magmatic and hydrothermal origin of the flood and to perform a frequency analysis of past minor hydrothermal jökulhlaups.

Changes of electrical conductivity of the metal surface layer by the laser alloying with foreign elements

NASA Astrophysics Data System (ADS)

Kostrubiec, Franciszek; Pawlak, Ryszard; Raczynski, Tomasz; Walczak, Maria

1994-09-01

Laser treatment of the surface of materials is of major importance for many fields technology. One of the latest and most significant methods of this treatment is laser alloying consisting of introducing foreign atoms into the metal surface layer during the reaction of laser radiation with the surface. This opens up vast possibilities for the modification of properties of such a layer (obtaining layers of increased microhardness, increased resistance to electroerosion in an electric arc, etc.). Conductivity of the material is a very important parameter in case of conductive materials used for electrical contacts. The paper presents the results of studies on change in electrical conductivity of the surface layer of metals alloyed with a laser. A comparative analysis of conductivity of base metal surface layers prior to and following laser treatment has been performed. Depending on the base metal and the alloying element, optical treatment parameters allowing a required change in the surface layer conductivity have been selected. A very important property of the contact material is its resistance to plastic strain. It affects the real value of contact surface coming into contact and, along with the material conductivity, determines contact resistance and the amount of heat generated in place of contact. These quantities are directly related to the initiation and the course of an arc discharge, hence they also affect resistance to electroerosion. The parameter that reflects plastic properties with loads concentrated on a small surface, as is the case with a reciprocal contact force of two real surfaces with their irregularities being in contact, is microhardness. In the paper, the results of investigations into microhardness of modified surface layers compared with base metal microhardness have been presented.

Ammonia-treated phosphate glasses useful for sealing to metals metals

DOEpatents

Brow, Richard K.; Day, Delbert E.

1991-01-01

A method of improving surface-dependent properties of phosphate glass such as durability and wear resistance without significantly affecting its thermal expansion coefficient is provided which comprises annealing the glass in a dry ammonia atmosphere at temperatures approximating the transition temperature of the glass. The ammonia annealing treatment of the present invention is carried out for a time sufficient to allow incorporation of a thin layer of nitrogen into the surface of the phosphate glass, and the treatment improves the durability of the glass without the reduction in the thermal expansion coefficient that has restricted the effectiveness of prior ammonia treatments. The improved phosphate glass resulting from this method is superior in wear resistance, yet maintains suitable thermal expansion properties so that it may be used effectively in a variety of applications requiring hermetic glass-metal seals.

Ammonia-treated phosphate glasses useful for sealing to metals

DOEpatents

Brow, R.K.; Day, D.E.

1991-09-03

A method of improving surface-dependent properties of phosphate glass such as durability and wear resistance without significantly affecting its thermal expansion coefficient is provided which comprises annealing the glass in a dry ammonia atmosphere at temperatures approximating the transition temperature of the glass. The ammonia annealing treatment of the present invention is carried out for a time sufficient to allow incorporation of a thin layer of nitrogen into the surface of the phosphate glass, and the treatment improves the durability of the glass without the reduction in the thermal expansion coefficient that has restricted the effectiveness of prior ammonia treatments. The improved phosphate glass resulting from this method is superior in wear resistance, yet maintains suitable thermal expansion properties so that it may be used effectively in a variety of applications requiring hermetic glass-metal seals.

AMP-Conjugated Quantum Dots: Low Immunotoxicity Both In Vitro and In Vivo

NASA Astrophysics Data System (ADS)

Dai, Tongcheng; Li, Na; Liu, Lu; Liu, Qin; Zhang, Yuanxing

2015-11-01

Quantum dots (QDs) are engineered nanoparticles that possess special optical and electronic properties and have shown great promise for future biomedical applications. In this work, adenosine 5'-monophosphate (AMP), a small biocompatible molecular, was conjugated to organic QDs to produce hydrophilic AMP-QDs. Using macrophage J774A.1 as the cell model, AMP-QDs exhibited both prior imaging property and low toxicity, and more importantly, triggered limited innate immune responses in macrophage, indicating low immunotoxicity in vitro. Using BALB/c mice as the animal model, AMP-QDs were found to be detained in immune organs but did not evoke robust inflammation responses or obvious histopathological abnormalities, which reveals low immunotoxicity in vivo. This work suggests that AMP is an excellent surface ligand with low immunotoxicity, and potentially used in surface modification for more extensive nanoparticles.

Critical assessment of inverse gas chromatography as means of assessing surface free energy and acid-base interaction of pharmaceutical powders.

PubMed

Telko, Martin J; Hickey, Anthony J

2007-10-01

Inverse gas chromatography (IGC) has been employed as a research tool for decades. Despite this record of use and proven utility in a variety of applications, the technique is not routinely used in pharmaceutical research. In other fields the technique has flourished. IGC is experimentally relatively straightforward, but analysis requires that certain theoretical assumptions are satisfied. The assumptions made to acquire some of the recently reported data are somewhat modified compared to initial reports. Most publications in the pharmaceutical literature have made use of a simplified equation for the determination of acid/base surface properties resulting in parameter values that are inconsistent with prior methods. In comparing the surface properties of different batches of alpha-lactose monohydrate, new data has been generated and compared with literature to allow critical analysis of the theoretical assumptions and their importance to the interpretation of the data. The commonly used (simplified) approach was compared with the more rigorous approach originally outlined in the surface chemistry literature. (c) 2007 Wiley-Liss, Inc.

Development of soils and communities of plants and arbuscular mycorrhizal fungi on West Virginia surface mines.

PubMed

Levy, Michael A; Cumming, Jonathan R

2014-11-01

Surface mining followed by reclamation to pasture is a major driver of land use and cover change in Appalachia. Prior research suggests that many aspects of ecosystem recovery are either slow or incomplete. We examined ecosystem structure-including soil physical and chemical properties, arbuscular mycorrhizal fungal (AMF) infectivity and community composition, and plant diversity and community composition-on a chronosequence of pasture-reclaimed surface mines and a non-mined pasture in northern West Virginia. Surface mining and reclamation dramatically altered ecosystem structure. Some aspects of ecosystem structure, including many measures of soil chemistry and infectivity of AMF, returned rapidly to levels found on the non-mined reference site. Other aspects of ecosystem structure, notably soil physical properties and AMF and plant communities, showed incomplete or no recovery over the short-to-medium term. In addition, invasive plants were prevalent on reclaimed mine sites. The results point to the need for investigation on how reclamation practices could minimize establishment of exotic invasive plant species and reduce the long-term impacts of mining on ecosystem structure and function.

Development of Soils and Communities of Plants and Arbuscular Mycorrhizal Fungi on West Virginia Surface Mines

NASA Astrophysics Data System (ADS)

Levy, Michael A.; Cumming, Jonathan R.

2014-11-01

Surface mining followed by reclamation to pasture is a major driver of land use and cover change in Appalachia. Prior research suggests that many aspects of ecosystem recovery are either slow or incomplete. We examined ecosystem structure—including soil physical and chemical properties, arbuscular mycorrhizal fungal (AMF) infectivity and community composition, and plant diversity and community composition—on a chronosequence of pasture-reclaimed surface mines and a non-mined pasture in northern West Virginia. Surface mining and reclamation dramatically altered ecosystem structure. Some aspects of ecosystem structure, including many measures of soil chemistry and infectivity of AMF, returned rapidly to levels found on the non-mined reference site. Other aspects of ecosystem structure, notably soil physical properties and AMF and plant communities, showed incomplete or no recovery over the short-to-medium term. In addition, invasive plants were prevalent on reclaimed mine sites. The results point to the need for investigation on how reclamation practices could minimize establishment of exotic invasive plant species and reduce the long-term impacts of mining on ecosystem structure and function.

Mechanical properties of anodized coatings over molten aluminum alloy

DOE PAGES

Grillet, Anne M.; Gorby, Allen D.; Trujillo, Steven M.; ...

2007-10-22

A method to measure interfacial mechanical properties at high temperatures and in a controlled atmosphere has been developed to study anodized aluminum surface coatings at temperatures where the interior aluminum alloy is molten. This is the first time that the coating strength has been studied under these conditions. In this study, we have investigated the effects of ambient atmosphere, temperature, and surface finish on coating strength for samples of aluminum alloy 7075. Surprisingly, the effective Young's modulus or strength of the coating when tested in air was twice as high as when samples were tested in an inert nitrogen ormore » argon atmosphere. Additionally, the effective Young's modulus of the anodized coating increased with temperature in an air atmosphere but was independent of temperature in an inert atmosphere. The effect of surface finish was also examined. Sandblasting the surface prior to anodization was found to increase the strength of the anodized coating with the greatest enhancement noted for a nitrogen atmosphere. Lastly, machining marks were not found to significantly affect the strength.« less

Research on Streamlines and Aerodynamic Heating for Unstructured Grids on High-Speed Vehicles

NASA Technical Reports Server (NTRS)

DeJarnette, Fred R.; Hamilton, H. Harris (Technical Monitor)

2001-01-01

Engineering codes are needed which can calculate convective heating rates accurately and expeditiously on the surfaces of high-speed vehicles. One code which has proven to meet these needs is the Langley Approximate Three-Dimensional Convective Heating (LATCH) code. It uses the axisymmetric analogue in an integral boundary-layer method to calculate laminar and turbulent heating rates along inviscid surface streamlines. It requires the solution of the inviscid flow field to provide the surface properties needed to calculate the streamlines and streamline metrics. The LATCH code has been used with inviscid codes which calculated the flow field on structured grids, Several more recent inviscid codes calculate flow field properties on unstructured grids. The present research develops a method to calculate inviscid surface streamlines, the streamline metrics, and heating rates using the properties calculated from inviscid flow fields on unstructured grids. Mr. Chris Riley, prior to his departure from NASA LaRC, developed a preliminary code in the C language, called "UNLATCH", to accomplish these goals. No publication was made on his research. The present research extends and improves on the code developed by Riley. Particular attention is devoted to the stagnation region, and the method is intended for programming in the FORTRAN 90 language.

Scanning-electron-microscopy observations and mechanical characteristics of ion-beam-sputtered surgical implant alloys

NASA Technical Reports Server (NTRS)

Weigand, A. J.; Meyer, M. L.; Ling, J. S.

1977-01-01

An electron bombardment ion thruster was used as an ion source to sputter the surfaces of orthopedic prosthetic metals. Scanning electron microscopy photomicrographs were made of each ion beam textured surface. The effect of ion texturing an implant surface on its bond to bone cement was investigated. A Co-Cr-W alloy and surgical stainless steel were used as representative hard tissue implant materials to determine effects of ion texturing on bulk mechanical properties. Work was done to determine the effect of substrate temperature on the development of an ion textured surface microstructure. Results indicate that the ultimate strength of the bulk materials is unchanged by ion texturing and that the microstructure will develop more rapidly if the substrate is heated prior to ion texturing.

Effect of Aluminum Coating on the Surface Properties of Ti-(~49 at. pct) Ni Alloy

NASA Astrophysics Data System (ADS)

Sinha, Arijit; Khan, Gobinda Gopal; Mondal, Bholanath; Majumdar, Jyotsna Dutta; Chattopadhyay, Partha Protim

2015-08-01

Stable porous layer of mixed Al2O3 and TiO2 has been formed on the Ti-(~49 at. pct) Ni alloy surface with an aim to suppress leaching of Ni from the alloy surface in contact with bio-fluid and to enhance the process of osseointegration. Aluminum coating on the Ni-Ti alloy surface prior to the anodization treatment has resulted in enhancement of depth and uniformity of pores. Thermal oxidation of the anodized aluminum-coated Ni-Ti samples has exhibited the formation of Al2O3 and TiO2 phases with dense porous structure. The nanoindentation and nanoscratch measurements have indicated a remarkable improvement in the hardness, wear resistance, and adhesiveness of the porous aluminum-coated Ni-Ti sample after thermal oxidation.

Laboratory investigations of Mars - Chemical and spectroscopic characteristics of a suite of clays as Mars soil analogs

NASA Technical Reports Server (NTRS)

Banin, Amos; Carle, Glenn C.; Chang, Sherwood; Coyne, Lelia M.; Orenberg, James B.

1988-01-01

A model system of Mars soil analog materials (MSAMs) was prepared, and the properties of these clays, such as chemical composition, surface-ion composition, water adsorption isotherms, and reflectance spectra, were examined. The results of these studies, performed along with simulations of the Viking Labeled Release Experiement using MSAMs, indicate that surface iron and adsorbed water are important determinants of clay behavior, as evidenced by changes in reflectance, water absorption, and clay surface reactions. The paper discusses the relevance of these results to the two major questions raised by prior explorations of Mars: has there ever been abundant water on Mars, and why is the iron found in the Martian soil not readily seen in the reflectance spectra of the surface?

Effect of manufacturing and experimental conditions on the mechanical and surface properties of silicone elastomer scaffolds used in endothelial mechanobiological studies.

PubMed

Campeau, Marc-Antoine; Lortie, Audrey; Tremblay, Pierrick; Béliveau, Marc-Olivier; Dubé, Dominic; Langelier, Ève; Rouleau, Léonie

2017-07-14

Mechanobiological studies allow the characterization of cell response to mechanical stresses. Cells need to be supported by a material with properties similar to the physiological environment. Silicone elastomers have been used to produce various in vitro scaffolds of different geometries for endothelial cell studies given its relevant mechanical, optical and surface properties. However, obtaining defined and repeatable properties is a challenge as depending on the different manufacturing and processing steps, mechanical and surface properties may vary significantly between research groups. The impact of different manufacturing and processing methods on the mechanical and surface properties was assessed by measuring the Young's modulus and the contact angle. Silicone samples were produced using different curing temperatures and processed with different sterilization techniques and hydrophilization conditions. Different curing temperatures were used to obtain materials of different stiffness with a chosen silicone elastomer, i.e. Sylgard 184 ® . Sterilization by boiling had a tendency to stiffen samples cured at lower temperatures whereas UV and ethanol did not alter the material properties. Hydrophilization using sulphuric acid allowed to decrease surface hydrophobicity, however this effect was lost over time as hydrophobic recovery occurred. Extended contact with water maintained decreased hydrophobicity up to 7 days. Mechanobiological studies require complete cell coverage of the scaffolds used prior to mechanical stresses exposure. Different concentrations of fibronectin and collagen were used to coat the scaffolds and cell seeding density was varied to optimize cell coverage. This study highlights the potential bias introduced by manufacturing and processing conditions needed in the preparation of scaffolds used in mechanobiological studies involving endothelial cells. As manufacturing, processing and cell culture conditions are known to influence cell adhesion and function, they should be more thoroughly assessed by research groups that perform such mechanobiological studies using silicone.

Mechanical and chemical effects of ion-texturing biomedical polymers

NASA Technical Reports Server (NTRS)

Weigand, A. J.; Cenkus, M. A.

1979-01-01

To determine whether sputter etching may provide substantial polymer surface texturing with insignificant changes in chemical and mechanical properties, an 8 cm beam diameter, electron bombardment, argon ion source was used to sputter etch (ion-texture process) nine biomedical polymers. The materials included silicone rubber, 32% carbon impregnated polyolefin, polyoxymethylene, polytetrafluoroethylene, ultrahigh molecular weight (UHMW) polyethylene, UHMW polyethylene with carbon fibers (10%), and several polyurethanes (bioelectric, segmented, and cross linked). Ion textured microtensile specimens of each material except UHMW polyethylene and UHMW polyethylene with 10% carbon fibers were used to determine the effect of ion texturing on tensile properties. Scanning electron microscopy was used to determine surface morphology changes, and electron spectroscopy for chemical analysis was used to analyze the near surface chemical changes that result from ion texturing. Ion energies of 500 eV with beam current densities ranging from 0.08 to 0.19 mA/sq cm were used to ion texture the various materials. Standard microtensile specimens of seven polymers were exposed to a saline environment for 24 hours prior to and during the tensile testing. The surface chemical changes resulting from sputter etching are minimal in spite of the often significant changes in the surface morphology.

The effect of spraying parameters on micro-structural properties of WC-12%Co coating deposited on copper substrate by HVOF process

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

Sathwara, Nishit, E-mail: nishit-25@live.in; Metallurgical & Materials Engineering Department, Indus University, Ahmedabad-382115; Jariwala, C., E-mail: chetanjari@yahoo.com

High Velocity Oxy-Fuel (HVOF) thermal sprayed coatingmade from Tungsten Carbide (WC) isconsidered as one of the most durable materials as wear resistance for industrial applications at room temperature. WC coating offers high wear resistance due to its high hardness and tough matrix imparts. The coating properties strongly depend on thermal spray processing parameters, surface preparation and surface finish. In this investigation, the effect of variousHVOF process parameters was studied on WC coating properties. The WC-12%Co coating was produced on Copper substrate. Prior to coating, theCopper substrate surface was prepared by grit blasting. WC-12%Co coatings were deposited on Coppersubstrates with varyingmore » process parameters such as Oxygen gas pressure, Air pressure, and spraying distance. Microstructure of coating was examined using Scanning Electron Microscope (SEM) and characterization of phasespresentin the coating was examined by X-Ray Diffraction (XRD). Microhardness of all coatingswas measured by VickerMicrohardness tester. At low Oxygen Pressure(10.00 bar), high Air pressure (7bar) and short nozzle to substrate distance of 170mm, best coating adhesion and porosity less structure isachieved on Coppersubstrate.« less

Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis.

PubMed

Read, Tania L; Macpherson, Julie V

2016-01-06

Boron doped diamond (BDD) electrodes have shown considerable promise as an electrode material where many of their reported properties such as extended solvent window, low background currents, corrosion resistance, etc., arise from the catalytically inert nature of the surface. However, if during the growth process, non-diamond-carbon (NDC) becomes incorporated into the electrode matrix, the electrochemical properties will change as the surface becomes more catalytically active. As such it is important that the electrochemist is aware of the quality and resulting key electrochemical properties of the BDD electrode prior to use. This paper describes a series of characterization steps, including Raman microscopy, capacitance, solvent window and redox electrochemistry, to ascertain whether the BDD electrode contains negligible NDC i.e. negligible sp(2) carbon. One application is highlighted which takes advantage of the catalytically inert and corrosion resistant nature of an NDC-free surface i.e. stable and quantifiable local proton and hydroxide production due to water electrolysis at a BDD electrode. An approach to measuring the local pH change induced by water electrolysis using iridium oxide coated BDD electrodes is also described in detail.

The effect of spraying parameters on micro-structural properties of WC-12%Co coating deposited on copper substrate by HVOF process

NASA Astrophysics Data System (ADS)

Sathwara, Nishit; Jariwala, C.; Chauhan, N.; Raole, P. M.; Basa, D. K.

2015-08-01

High Velocity Oxy-Fuel (HVOF) thermal sprayed coatingmade from Tungsten Carbide (WC) isconsidered as one of the most durable materials as wear resistance for industrial applications at room temperature. WC coating offers high wear resistance due to its high hardness and tough matrix imparts. The coating properties strongly depend on thermal spray processing parameters, surface preparation and surface finish. In this investigation, the effect of variousHVOF process parameters was studied on WC coating properties. The WC-12%Co coating was produced on Copper substrate. Prior to coating, theCopper substrate surface was prepared by grit blasting. WC-12%Co coatings were deposited on Coppersubstrates with varying process parameters such as Oxygen gas pressure, Air pressure, and spraying distance. Microstructure of coating was examined using Scanning Electron Microscope (SEM) and characterization of phasespresentin the coating was examined by X-Ray Diffraction (XRD). Microhardness of all coatingswas measured by VickerMicrohardness tester. At low Oxygen Pressure(10.00 bar), high Air pressure (7bar) and short nozzle to substrate distance of 170mm, best coating adhesion and porosity less structure isachieved on Coppersubstrate.

Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

PubMed Central

Read, Tania L.; Macpherson, Julie V.

2016-01-01

Boron doped diamond (BDD) electrodes have shown considerable promise as an electrode material where many of their reported properties such as extended solvent window, low background currents, corrosion resistance, etc., arise from the catalytically inert nature of the surface. However, if during the growth process, non-diamond-carbon (NDC) becomes incorporated into the electrode matrix, the electrochemical properties will change as the surface becomes more catalytically active. As such it is important that the electrochemist is aware of the quality and resulting key electrochemical properties of the BDD electrode prior to use. This paper describes a series of characterization steps, including Raman microscopy, capacitance, solvent window and redox electrochemistry, to ascertain whether the BDD electrode contains negligible NDC i.e. negligible sp2 carbon. One application is highlighted which takes advantage of the catalytically inert and corrosion resistant nature of an NDC-free surface i.e. stable and quantifiable local proton and hydroxide production due to water electrolysis at a BDD electrode. An approach to measuring the local pH change induced by water electrolysis using iridium oxide coated BDD electrodes is also described in detail. PMID:26779959

The effect of physiological conditions on the surface structure of proteins: Setting the scene for human digestion of emulsions

NASA Astrophysics Data System (ADS)

Maldonado-Valderrama, J.; Gunning, A. P.; Ridout, M. J.; Wilde, P. J.; Morris, V. J.

2009-10-01

Understanding and manipulating the interfacial mechanisms that control human digestion of food emulsions is a crucial step towards improved control of dietary intake. This article reports initial studies on the effects of the physiological conditions within the stomach on the properties of the film formed by the milk protein ( β -lactoglobulin) at the air-water interface. Atomic force microscopy (AFM), surface tension and surface rheology techniques were used to visualize and examine the effect of gastric conditions on the network structure. The effects of changes in temperature, pH and ionic strength on a pre-formed interfacial structure were characterized in order to simulate the actual digestion process. Changes in ionic strength had little effect on the surface properties. In isolation, acidification reduced both the dilatational and the surface shear modulus, mainly due to strong repulsive electrostatic interactions within the surface layer and raising the temperature to body temperature accelerated the rearrangements within the surface layer, resulting in a decrease of the dilatational response and an increase of surface pressure. Together pH and temperature display an unexpected synergism, independent of the ionic strength. Thus, exposure of a pre-formed interfacial β -lactoglobulin film to simulated gastric conditions reduced the surface dilatational modulus and surface shear moduli. This is attributed to a weakening of the surface network in which the surface rearrangements of the protein prior to exposure to gastric conditions might play a crucial role.

TU-F-BRF-02: MR-US Prostate Registration Using Patient-Specific Tissue Elasticity Property Prior for MR-Targeted, TRUS-Guided HDR Brachytherapy

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

Yang, X; Rossi, P; Ogunleye, T

2014-06-15

Purpose: High-dose-rate (HDR) brachytherapy has become a popular treatment modality for prostate cancer. Conventional transrectal ultrasound (TRUS)-guided prostate HDR brachytherapy could benefit significantly from MR-targeted, TRUS-guided procedure where the tumor locations, acquired from the multiparametric MRI, are incorporated into the treatment planning. In order to enable this integration, we have developed a MR-TRUS registration with a patient-specific biomechanical elasticity prior. Methods: The proposed method used a biomechanical elasticity prior to guide the prostate volumetric B-spline deformation in the MRI and TRUS registration. The patient-specific biomechanical elasticity prior was generated using ultrasound elastography, where two 3D TRUS prostate images were acquiredmore » under different probe-induced pressures during the HDR procedure, which takes 2-4 minutes. These two 3D TRUS images were used to calculate the local displacement (elasticity map) of two prostate volumes. The B-spline transformation was calculated by minimizing the Euclidean distance between the normalized attribute vectors of the prostate surface landmarks on the MR and TRUS. This technique was evaluated through two studies: a prostate-phantom study and a pilot study with 5 patients undergoing prostate HDR treatment. The accuracy of our approach was assessed through the locations of several landmarks in the post-registration and TRUS images; our registration results were compared with the surface-based method. Results: For the phantom study, the mean landmark displacement of the proposed method was 1.29±0.11 mm. For the 5 patients, the mean landmark displacement of the surface-based method was 3.25±0.51 mm; our method, 1.71±0.25 mm. Therefore, our proposed method of prostate registration outperformed the surfaced-based registration significantly. Conclusion: We have developed a novel MR-TRUS prostate registration approach based on patient-specific biomechanical elasticity prior. Successful integration of multi-parametric MR and TRUS prostate images provides a prostate-cancer map for treatment planning, enables accurate dose planning and delivery, and potentially enhances prostate HDR treatment outcome.« less

Analysis and Evaluation of Technical Data on the Photochromic and Non- Linear Optical Properties of Materials

DTIC Science & Technology

1989-03-01

relatively small contractural effort is to provide technical assistance to Dr. Frank Patten (DARPA) in evaluating data on materials, especially... Musikant , S. (ed.), Advances in Materials for Active Optics, Proceedings of SPIE, Volume 567, SPIE:Washington, 1985. [22] Lewis, Aaron, Del Priore...polysilane," J. Appl. Phys. 60 (1986) 3040-3044. [146] Hache, F., Ricard, D., Flytzanis, C., "Optical nonlinearities of small metal particles: surface

Integrating prior information into microwave tomography Part 1: Impact of detail on image quality.

PubMed

Kurrant, Douglas; Baran, Anastasia; LoVetri, Joe; Fear, Elise

2017-12-01

The authors investigate the impact that incremental increases in the level of detail of patient-specific prior information have on image quality and the convergence behavior of an inversion algorithm in the context of near-field microwave breast imaging. A methodology is presented that uses image quality measures to characterize the ability of the algorithm to reconstruct both internal structures and lesions embedded in fibroglandular tissue. The approach permits key aspects that impact the quality of reconstruction of these structures to be identified and quantified. This provides insight into opportunities to improve image reconstruction performance. Patient-specific information is acquired using radar-based methods that form a regional map of the breast. This map is then incorporated into a microwave tomography algorithm. Previous investigations have demonstrated the effectiveness of this approach to improve image quality when applied to data generated with two-dimensional (2D) numerical models. The present study extends this work by generating prior information that is customized to vary the degree of structural detail to facilitate the investigation of the role of prior information in image formation. Numerical 2D breast models constructed from magnetic resonance (MR) scans, and reconstructions formed with a three-dimensional (3D) numerical breast model are used to assess if trends observed for the 2D results can be extended to 3D scenarios. For the blind reconstruction scenario (i.e., no prior information), the breast surface is not accurately identified and internal structures are not clearly resolved. A substantial improvement in image quality is achieved by incorporating the skin surface map and constraining the imaging domain to the breast. Internal features within the breast appear in the reconstructed image. However, it is challenging to discriminate between adipose and glandular regions and there are inaccuracies in both the structural properties of the glandular region and the dielectric properties reconstructed within this structure. Using a regional map with a skin layer only marginally improves this situation. Increasing the structural detail in the prior information to include internal features leads to reconstructions for which the interface that delineates the fat and gland regions can be inferred. Different features within the glandular region corresponding to tissues with varying relative permittivity values, such as a lesion embedded within glandular structure, emerge in the reconstructed images. Including knowledge of the breast surface and skin layer leads to a substantial improvement in image quality compared to the blind case, but the images have limited diagnostic utility for applications such as tumor response tracking. The diagnostic utility of the reconstruction technique is improved considerably when patient-specific structural information is used. This qualitative observation is supported quantitatively with image metrics. © 2017 American Association of Physicists in Medicine.

Study of advanced composite structural design concepts for an arrow wing supersonic cruise configuration

NASA Technical Reports Server (NTRS)

Turner, M. J.; Grande, D. L.

1978-01-01

Based on estimated graphite and boron fiber properties, allowable stresses and strains were established for advanced composite materials. Stiffened panel and conventional sandwich panel concepts were designed and analyzed, using graphite/polyimide and boron/polyimide materials. The conventional sandwich panel was elected as the structural concept for the modified wing structure. Upper and lower surface panels of the arrow wing structure were then redesigned, using high strength graphite/polyimide sandwich panels, retaining the titanium spars and ribs from the prior study. The ATLAS integrated analysis and design system was used for stress analysis and automated resizing of surface panels. Flutter analysis of the hybrid structure showed a significant decrease in flutter speed relative to the titanium wing design. The flutter speed was increased to that of the titanium design by selective increase in laminate thickness and by using graphite fibers with properties intermediate between high strength and high modulus values.

Altered Sputum Microstructure as a Marker of Airway Obstruction in Cystic Fibrosis Patients

NASA Astrophysics Data System (ADS)

Duncan, Gregg; Jung, James; West, Natalie; Boyle, Michael; Suk, Jung Soo; Hanes, Justin

In the lungs of cystic fibrosis (CF) patients, highly viscoelastic mucus remains stagnant in the lung leading to obstructed airways prone to recurrent infections. Bulk-fluid rheological measurement is primarily used to assess the pathological features of mucus. However, this approach is limited in detecting microscopic properties on the length scale of pathogens and immune cells. We have shown in prior work based on the transport of muco-inert nanoparticles (MIP) in CF sputum that patients can carry significantly different microstructural properties. In this study, we aimed to determine the factors leading to variations between patients in sputum microstructure and their clinical implications. The microrheological properties of CF sputum were measured using multi-particle tracking experiments of MIP. MIP were made by grafting polyethylene glycol onto the surface of polystyrene nanoparticles which prior work has shown prevents adhesion to CF sputum. Biochemical analyses show that sputum microstructure was significantly altered by elevated mucin and DNA content. Reduction in sputum pore size is characteristic of patients with obstructed airways as indicated by measured pulmonary function tests. Our microstructural read-out may serve as a novel biomarker for CF.

Water adsorption on the Fe3O4(111) surface: dissociation and network formation.

PubMed

Zaki, Eman; Mirabella, Francesca; Ivars-Barceló, Francisco; Seifert, Jan; Carey, Spencer; Shaikhutdinov, Shamil; Freund, Hans-Joachim; Li, Xiaoke; Paier, Joachim; Sauer, Joachim

2018-06-13

We monitored adsorption of water on a well-defined Fe3O4(111) film surface at different temperatures as a function of coverage using infrared reflection-absorption spectroscopy, temperature programmed desorption, and single crystal adsorption calorimetry. Additionally, density functional theory was employed using a Fe3O4(111)-(2 × 2) slab model to generate 15 energy minimum structures for various coverages. Corresponding vibrational properties of the adsorbed water species were also computed. The results show that water molecules readily dissociate on regular surface Fetet1-O ion pairs to form "monomers", i.e., terminal Fe-OH and surface OH groups. Further water molecules adsorb on the hydroxyl covered surface non-dissociatively and form "dimers" and larger oligomers, which ultimately assemble into an ordered (2 × 2) hydrogen-bonded network structure with increasing coverage prior to the formation of a solid water film.

Preparation and properties of an internal mold release for rigid urethane foam

NASA Astrophysics Data System (ADS)

Paker, B. G.

1980-08-01

Most mold release agents used in the molding of rigid polyurethane foam are applied to the internal surfaces of the mold. These materials form a thin layer between the surface of the mold and the foam, allowing for easy release of the molded parts. This type of mold release must be applied prior to each molding operation; and, after repeated use, cleaning of the mold is required. Small amounts of this mold release are transferred to the molded part, resulting in a part with poor surface bondability characteristics. An internal release agent, which can be mixed in a urethane foam resin was investigated. The internal mold release provided good releasability and resulted in urethane foam that has excellent surface bondability. No compatibility problems are expected from the use of this type of release agent.

Strongly correlated surface states

NASA Astrophysics Data System (ADS)

Alexandrov, Victor A.

Everything has an edge. However trivial, this phrase has dominated theoretical condensed matter in the past half a decade. Prior to that, questions involving the edge considered to be more of an engineering problem rather than a one of fundamental science: it seemed self-evident that every edge is different. However, recent advances proved that many surface properties enjoy a certain universality, and moreover, are 'topologically' protected. In this thesis I discuss a selected range of problems that bring together topological properties of surface states and strong interactions. Strong interactions alone can lead to a wide spectrum of emergent phenomena: from high temperature superconductivity to unconventional magnetic ordering; interactions can change the properties of particles, from heavy electrons to fractional charges. It is a unique challenge to bring these two topics together. The thesis begins by describing a family of methods and models with interactions so high that electrons effectively disappear as particles and new bound states arise. By invoking the AdS/CFT correspondence we can mimic the physical systems of interest as living on the surface of a higher dimensional universe with a black hole. In a specific example we investigate the properties of the surface states and find helical spin structure of emerged particles. The thesis proceeds from helical particles on the surface of black hole to a surface of samarium hexaboride: an f-electron material with localized magnetic moments at every site. Interactions between electrons in the bulk lead to insulating behavior, but the surfaces found to be conducting. This observation motivated an extensive research: weather the origin of conduction is of a topological nature. Among our main results, we confirm theoretically the topological properties of SmB6; introduce a new framework to address similar questions for this type of insulators, called Kondo insulators. Most notably we introduce the idea of Kondo band banding (KBB): a modification of edges and their properties due to interactions. We study (chapter 5) a simplified 1D Kondo model, showing that the topology of its ground state is unstable to KBB. Chapter 6 expands the study to 3D: we argue that not only KBB preserves the topology but it could also explain the experimentally observed anomalously high Fermi velocity at the surface as the case of large KBB effect.

Nanoscale Insight and Control of Structural and Electronic Properties of Organic Semiconductor / Metal Interfaces

NASA Astrophysics Data System (ADS)

Maughan, Bret

Organic semiconductor interfaces are promising materials for use in next-generation electronic and optoelectronic devices. Current models for metal-organic interfacial electronic structure and dynamics are inadequate for strongly hybridized systems. This work aims to address this issue by identifying the factors most important for understanding chemisorbed interfaces with an eye towards tuning the interfacial properties. Here, I present the results of my research on chemisorbed interfaces formed between thin-films of phthalocyanine molecules grown on monocrystalline Cu(110). Using atomically-resolved nanoscale imaging in combination with surface-sensitive photoemission techniques, I show that single-molecule level interactions control the structural and electronic properties of the interface. I then demonstrate that surface modifications aimed at controlling interfacial interactions are an effective way to tailor the physical and electronic structure of the interface. This dissertation details a systematic investigation of the effect of molecular and surface functionalization on interfacial interactions. To understand the role of molecular structure, two types of phthalocyanine (Pc) molecules are studied: non-planar, dipolar molecules (TiOPc), and planar, non-polar molecules (H2Pc and CuPc). Multiple adsorption configurations for TiOPc lead to configuration-dependent self-assembly, Kondo screening, and electronic energy-level alignment. To understand the role of surface structure, the Cu(110) surface is textured and passivated by oxygen chemisorption prior to molecular deposition, which gives control over thin-film growth and interfacial electronic structure in H2Pc and CuPc films. Overall, the work presented here demonstrates a method for understanding interfacial electronic structure of strongly hybridized interfaces, an important first step towards developing more robust models for metal-organic interfaces, and reliable, predictive tuning of interfacial properties.

High-Frequency Focused Water-Coupled Ultrasound Used for Three-Dimensional Surface Depression Profiling

NASA Technical Reports Server (NTRS)

Roth, Don J.; Whalen, Mike F.; Hendricks, J. Lynne; Bodis, James R.

2001-01-01

To interface with other solids, many surfaces are engineered via methods such as plating, coating, and machining to produce a functional surface ensuring successful end products. In addition, subsurface properties such as hardness, residual stress, deformation, chemical composition, and microstructure are often linked to surface characteristics. Surface topography, therefore, contains the signatures of the surface and possibly links to volumetric properties, and as a result serves as a vital link between surface design, manufacturing, and performance. Hence, surface topography can be used to diagnose, monitor, and control fabrication methods. At the NASA Glenn Research Center, the measurement of surface topography is important in developing high-temperature structural materials and for profiling the surface changes of materials during microgravity combustion experiments. A prior study demonstrated that focused air-coupled ultrasound at 1 MHz could profile surfaces with a 25-m depth resolution and a 400-m lateral resolution over a 1.4-mm depth range. In this work, we address the question of whether higher frequency focused water-coupled ultrasound can improve on these specifications. To this end, we employed 10- and 25-MHz focused ultrasonic transducers in the water-coupled mode. The surface profile results seen in this investigation for 25-MHz water-coupled ultrasound, in comparison to those for 1-MHz air-coupled ultrasound, represent an 8 times improvement in depth resolution (3 vs. 25 m seen in practice), an improvement of at least 2 times in lateral resolution (180 vs. 400 m calculated and observed in practice), and an improvement in vertical depth range of 4 times (calculated).

Thermal Performance of Low Layer Density Multilayer Insu1ation Using Liquid Nitrogen

NASA Technical Reports Server (NTRS)

Johnson, Wesley L.; Fesmire, James E.

2011-01-01

In order to support long duration cryogenic propellant storage, the Cryogenic Fluid Management (CFM) Project of the Exploration Technology Development Program (ETDP) is investigating the long duration storage propertie$ of liquid methane on the lunar surface. The Methane Lunar Surface Thermal Control (MLSTC) testing is using a tank of the approximate dimensions of the Altair ascent tanks inside of a vacuum chamber to simulate the environment in low earth orbit and on the lunar surface. The thermal performance testing of multilayer insulation (MLI) coupons that are fabricated identically to the tank applied insulation is necessary to understand the performance of the blankets and to be able to predict the performance of the insulation prior to testing. This coupon testing was completed in Cryostat-100 at the Cryogenics Test Laboratory. The results showed the properties of the insulation as a function of layer density, number of layers, and warm boundary temperature. These results aid in the understanding of the performance parameters o fMLI and help to complete the body of literature on the topic.

Physical and chemical characterization of waste wood derived biochars.

PubMed

Yargicoglu, Erin N; Sadasivam, Bala Yamini; Reddy, Krishna R; Spokas, Kurt

2015-02-01

Biochar, a solid byproduct generated during waste biomass pyrolysis or gasification in the absence (or near-absence) of oxygen, has recently garnered interest for both agricultural and environmental management purposes owing to its unique physicochemical properties. Favorable properties of biochar include its high surface area and porosity, and ability to adsorb a variety of compounds, including nutrients, organic contaminants, and some gases. Physical and chemical properties of biochars are dictated by the feedstock and production processes (pyrolysis or gasification temperature, conversion technology and pre- and post-treatment processes, if any), which vary widely across commercially produced biochars. In this study, several commercially available biochars derived from waste wood are characterized for physical and chemical properties that can signify their relevant environmental applications. Parameters characterized include: physical properties (particle size distribution, specific gravity, density, porosity, surface area), hydraulic properties (hydraulic conductivity and water holding capacity), and chemical and electrochemical properties (organic matter and organic carbon contents, pH, oxidation-reduction potential and electrical conductivity, zeta potential, carbon, nitrogen and hydrogen (CHN) elemental composition, polycyclic aromatic hydrocarbons (PAHs), heavy metals, and leachable PAHs and heavy metals). A wide range of fixed carbon (0-47.8%), volatile matter (28-74.1%), and ash contents (1.5-65.7%) were observed among tested biochars. A high variability in surface area (0.1-155.1g/m(2)) and PAH and heavy metal contents of the solid phase among commercially available biochars was also observed (0.7-83 mg kg(-1)), underscoring the importance of pre-screening biochars prior to application. Production conditions appear to dictate PAH content--with the highest PAHs observed in biochar produced via fast pyrolysis and lowest among the gasification-produced biochars. Copyright © 2014 Elsevier Ltd. All rights reserved.

Persistently Auxetic Materials: Engineering the Poisson Ratio of 2D Self-Avoiding Membranes under Conditions of Non-Zero Anisotropic Strain.

PubMed

Ulissi, Zachary W; Govind Rajan, Ananth; Strano, Michael S

2016-08-23

Entropic surfaces represented by fluctuating two-dimensional (2D) membranes are predicted to have desirable mechanical properties when unstressed, including a negative Poisson's ratio ("auxetic" behavior). Herein, we present calculations of the strain-dependent Poisson ratio of self-avoiding 2D membranes demonstrating desirable auxetic properties over a range of mechanical strain. Finite-size membranes with unclamped boundary conditions have positive Poisson's ratio due to spontaneous non-zero mean curvature, which can be suppressed with an explicit bending rigidity in agreement with prior findings. Applying longitudinal strain along a singular axis to this system suppresses this mean curvature and the entropic out-of-plane fluctuations, resulting in a molecular-scale mechanism for realizing a negative Poisson's ratio above a critical strain, with values significantly more negative than the previously observed zero-strain limit for infinite sheets. We find that auxetic behavior persists over surprisingly high strains of more than 20% for the smallest surfaces, with desirable finite-size scaling producing surfaces with negative Poisson's ratio over a wide range of strains. These results promise the design of surfaces and composite materials with tunable Poisson's ratio by prestressing platelet inclusions or controlling the surface rigidity of a matrix of 2D materials.

Shape Memory Polymers Containing Higher Acrylate Content Display Increased Endothelial Cell Attachment

PubMed Central

Govindarajan, Tina; Shandas, Robin

2018-01-01

Shape Memory Polymers (SMPs) are smart materials that can recall their shape upon the application of a stimulus, which makes them appealing materials for a variety of applications, especially in biomedical devices. Most prior SMP research has focused on tuning bulk properties; studying surface effects of SMPs may extend the use of these materials to blood-contacting applications, such as cardiovascular stents, where surfaces that support rapid endothelialization have been correlated to stent success. Here, we evaluate endothelial attachment onto the surfaces of a family of SMPs previously developed in our group that have shown promise for biomedical devices. Nine SMP formulations containing varying amounts of tert-Butyl acrylate (tBA) and Poly(ethylene glycol) dimethacrylate (PEGDMA) were analyzed for endothelial cell attachment. Dynamic mechanical analysis (DMA), contact angle studies, and atomic force microscopy (AFM) were used to verify bulk and surface properties of the SMPs. Human umbilical vein endothelial cell (HUVEC) attachment and viability was verified using fluorescent methods. Endothelial cells preferentially attached to SMPs with higher tBA content, which have rougher, more hydrophobic surfaces. HUVECs also displayed an increased metabolic activity on these high tBA SMPs over the course of the study. This class of SMPs may be promising candidates for next generation blood-contacting devices. PMID:29707382

Spectroscopic observations of the Moon at the lunar surface

NASA Astrophysics Data System (ADS)

Wu, Yunzhao; Hapke, Bruce

2018-02-01

The Moon's reflectance spectrum records many of its important properties. However, prior to Chang'E-3 (CE-3), no spectra had previously been measured on the lunar surface. Here we show the in situ reflectance spectra of the Moon acquired on the lunar surface by the Visible-Near Infrared Spectrometer (VNIS) onboard the CE-3 rover. The VNIS detected thermal radiation from the lunar regolith, though with much shorter wavelength range than typical thermal radiometer. The measured temperatures are higher than expected from theoretical model, indicating low thermal inertia of the lunar soil and the effects of grain facet on soil temperature in submillimeter scale. The in situ spectra also reveal that 1) brightness changes visible from orbit are related to the reduction in maturity due to the removal of the fine and weathered particles by the lander's rocket exhaust, not the smoothing of the surface and 2) the spectra of the uppermost soil detected by remote sensing exhibit substantial differences with that immediately beneath, which has important implications for the remote compositional analysis. The reflectance spectra measured by VNIS not only reveal the thermal, compositional, and space-weathering properties of the Moon but also provide a means for the calibration of optical instruments that view the surface remotely.

Effects of Laser Re-melting on the Corrosion Properties of HVOF Coatings

NASA Astrophysics Data System (ADS)

Yilbas, B. S.; Toor, I. H.; Patel, F.; Baig, M. A.

2013-05-01

HVOF coating of Inconel 625 powder on carbon steel is carried out. Laser melting of the resulting coating is realized to improve coating structural integrity. Morphological and microstructural changes are examined in the coating prior and after laser treatment process using scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction (XRD). The residual stress developed is measured on the surface vicinity of the laser-treated coating using the XRD technique. The corrosion resistance of the laser-treated and untreated coating surfaces is measured, incorporating the potentiodynamic tests in 0.5 M NaCl aqueous solution. It is found that laser treatment reduces the pores and produces cellular structures with different sizes and orientations in the coating. Laser-controlled melting improves the corrosion resistance of the coating surface.

Optimal Multiple Surface Segmentation With Shape and Context Priors

PubMed Central

Bai, Junjie; Garvin, Mona K.; Sonka, Milan; Buatti, John M.; Wu, Xiaodong

2014-01-01

Segmentation of multiple surfaces in medical images is a challenging problem, further complicated by the frequent presence of weak boundary evidence, large object deformations, and mutual influence between adjacent objects. This paper reports a novel approach to multi-object segmentation that incorporates both shape and context prior knowledge in a 3-D graph-theoretic framework to help overcome the stated challenges. We employ an arc-based graph representation to incorporate a wide spectrum of prior information through pair-wise energy terms. In particular, a shape-prior term is used to penalize local shape changes and a context-prior term is used to penalize local surface-distance changes from a model of the expected shape and surface distances, respectively. The globally optimal solution for multiple surfaces is obtained by computing a maximum flow in a low-order polynomial time. The proposed method was validated on intraretinal layer segmentation of optical coherence tomography images and demonstrated statistically significant improvement of segmentation accuracy compared to our earlier graph-search method that was not utilizing shape and context priors. The mean unsigned surface positioning errors obtained by the conventional graph-search approach (6.30 ± 1.58 μm) was improved to 5.14 ± 0.99 μm when employing our new method with shape and context priors. PMID:23193309

Influence of stearic acid on the structure and rheological behavior of injection-molded ZTA suspensions

NASA Astrophysics Data System (ADS)

Lin, Cong; Wang, Bo; Cheng, Yao; Wang, Cao

2013-01-01

The zirconia-toughened-alumina (ZTA) composite powder was exposed to a prior ball milling treatment with a small amount of stearic acid (SA) before the traditional blending process. The effect of different amounts of stearic acid on surface properties of the powder, the particle size distribution of the powder, and the rheological properties of the suspension were systematically studied within the design of experiments. Fourier transformation infrared spectroscopy (FTIR) analysis was used to prove the chemical interaction between the stearic acid and the ZTA powder. The effects of SA content on the particle sizes and their distribution were carefully examined. Rheological properties such as viscosity, yield stress, and power law exponent of the suspensions were determined within a temperature range of 140-170 °C. The optimal content of SA to improve the properties of the suspensions was found to be 3 wt.%.

Laser-based surface preparation of composite laminates leads to improved electrodes for electrical measurements

NASA Astrophysics Data System (ADS)

Almuhammadi, Khaled; Selvakumaran, Lakshmi; Alfano, Marco; Yang, Yang; Bera, Tushar Kanti; Lubineau, Gilles

2015-12-01

Electrical impedance tomography (EIT) is a low-cost, fast and effective structural health monitoring technique that can be used on carbon fiber reinforced polymers (CFRP). Electrodes are a key component of any EIT system and as such they should feature low resistivity as well as high robustness and reproducibility. Surface preparation is required prior to bonding of electrodes. Currently this task is mostly carried out by traditional sanding. However this is a time consuming procedure which can also induce damage to surface fibers and lead to spurious electrode properties. Here we propose an alternative processing technique based on the use of pulsed laser irradiation. The processing parameters that result in selective removal of the electrically insulating resin with minimum surface fiber damage are identified. A quantitative analysis of the electrical contact resistance is presented and the results are compared with those obtained using sanding.

Heat transfer to two-phase air/water mixtures flowing in small tubes with inlet disequilibrium

NASA Technical Reports Server (NTRS)

Janssen, J. M.; Florschuetz, L. W.; Fiszdon, J. P.

1986-01-01

The cooling of gas turbine components was the subject of considerable research. The problem is difficult because the available coolant, compressor bleed air, is itself quite hot and has relatively poor thermophysical properties for a coolant. Injecting liquid water to evaporatively cool the air prior to its contact with the hot components was proposed and studied, particularly as a method of cooling for contingency power applications. Injection of a small quantity of cold liquid water into a relatively hot coolant air stream such that evaporation of the liquid is still in process when the coolant contacts the hot component was studied. No approach was found whereby heat transfer characteristics could be confidently predicted for such a case based solely on prior studies. It was not clear whether disequilibrium between phases at the inlet to the hot component section would improve cooling relative to that obtained where equilibrium was established prior to contact with the hot surface.

Enhanced fatigue performance of porous coated Ti6Al4V biomedical alloy

NASA Astrophysics Data System (ADS)

Apachitei, I.; Leoni, A.; Riemslag, A. C.; Fratila-Apachitei, L. E.; Duszczyk, J.

2011-05-01

Biofunctional coatings are necessary to improve integration of titanium implants in the host tissue but they may be detrimental for the implant fatigue properties. This study presents an attempt towards enhancement of the in vitro fatigue strength of plasma electrolytic oxidation coated Ti6Al4V alloy by applying shot peening process prior to coating. The electrolytic oxidation was performed in calcium acetate and calcium glycerophosphate electrolytes that allowed formation of porous oxide coatings with high surface free energy and apatite like ability. A deformed surface layer coupled with induced residual compressive stresses seem to affect oxide growth rate and fatigue behavior of the titanium alloy.

Correspondence between AXAF TMA X-ray performance and models based upon mechanical and visible light measurements

NASA Technical Reports Server (NTRS)

Van Speybroeck, L.; Mckinnon, P. J.; Murray, S. S.; Primini, F. A.; Schwartz, D. A.; Zombeck, M. V.; Dailey, C. C.; Reily, J. C.; Weisskopf, M. C.; Wyman, C. L.

1986-01-01

The AXAF Technology Mirror Assembly (TMA) was characterized prior to X-ray testing by properties measured mechanically or with visible light; these include alignment offsets, roundness and global-axial-slope errors, axial-figure errors with characteristic lengths greater than about five mm, and surface roughness with scale lengths between about 0.005 and 0.5 mm. The X-ray data of Schwartz et al. (1985) are compared with predictions based upon the mechanical and visible light measurements.

The influence of tennis court surfaces on player perceptions and biomechanical response.

PubMed

Starbuck, Chelsea; Damm, Loïc; Clarke, James; Carré, Matt; Capel-Davis, Jamie; Miller, Stuart; Stiles, Victoria; Dixon, Sharon

2016-09-01

This study aimed to examine player perceptions and biomechanical responses to tennis surfaces and to evaluate the influence of prior clay court experience. Two groups with different clay experiences (experience group, n = 5 and low-experience group, n = 5) performed a 180° turning movement. Three-dimensional ankle and knee movements (50 Hz), plantar pressure of the turning step (100 Hz) and perception data (visual analogue scale questionnaire) were collected for two tennis courts (acrylic and clay). Greater initial knee flexion (acrylic 20. 8 ± 11.2° and clay 32.5 ± 9.4°) and a more upright position were reported on the clay compared to the acrylic court (P < 0.05). This suggests adaptations to increase player stability on clay. Greater hallux pressures and lower midfoot pressures were observed on the clay court, allowing for sliding whilst providing grip at the forefoot. Players with prior clay court experience exhibited later peak knee flexion compared to those with low experience. All participants perceived the differences in surface properties between courts and thus responded appropriately to these differences. The level of previous clay court experience did not influence players' perceptions of the surfaces; however, those with greater clay court experience may reduce injury risk as a result of reduced loading through later peak knee flexion.

Confidence set inference with a prior quadratic bound

NASA Technical Reports Server (NTRS)

Backus, George E.

1989-01-01

In the uniqueness part of a geophysical inverse problem, the observer wants to predict all likely values of P unknown numerical properties z=(z sub 1,...,z sub p) of the earth from measurement of D other numerical properties y (sup 0) = (y (sub 1) (sup 0), ..., y (sub D (sup 0)), using full or partial knowledge of the statistical distribution of the random errors in y (sup 0). The data space Y containing y(sup 0) is D-dimensional, so when the model space X is infinite-dimensional the linear uniqueness problem usually is insoluble without prior information about the correct earth model x. If that information is a quadratic bound on x, Bayesian inference (BI) and stochastic inversion (SI) inject spurious structure into x, implied by neither the data nor the quadratic bound. Confidence set inference (CSI) provides an alternative inversion technique free of this objection. Confidence set inference is illustrated in the problem of estimating the geomagnetic field B at the core-mantle boundary (CMB) from components of B measured on or above the earth's surface.

Is Mars Sample Return Required Prior to Sending Humans to Mars?

NASA Technical Reports Server (NTRS)

Carr, Michael; Abell, Paul; Allwood, Abigail; Baker, John; Barnes, Jeff; Bass, Deborah; Beaty, David; Boston, Penny; Brinkerhoff, Will; Budney, Charles;

In-situ ellipsometric studies of optical and surface properties of GaAs(100) at elevated temperatures

NASA Technical Reports Server (NTRS)

Yao, Huade; Snyder, Paul G.

1991-01-01

A rotating-polarizer ellipsometer was attached to an ultrahigh vacuum (UHV) chamber. A GaAs(100) sample was introduced into the UHV chamber and heated at anumber of fixed elevated temperatures, without arsenic overpressure. In-situ spectroscopic ellipsometric (SE) measurements were taken, through a pair of low-strain quartz windows, to monitor the surface changes and measure the pseudodielectric functions at elevated temperatures. Real-time data from GaAs surface covered with native oxide showed clearly the evolution of oxide desorption at approximately 580 C. In addition, surface degradation was found before and after the oxide desorption. An oxide free and smooth GaAs surface was obtained by depositing an arsenic protective coating onto a molecular beam epitaxy grown GaAs surface. The arsenic coating was evaporated immediately prior to SE measurements. A comparison showed that our room temperature data from this GaAs surface, measured in the UHV, are in good agreement with those in the literature obtained by wet-chemical etching. The surface also remained clean and smooth at higher temperatures, so that reliable temperature-dependent dielectric functions were obtained.

The Improved Dual-view Field Goniometer System FIGOS

PubMed Central

Schopfer, Jürg; Dangel, Stefan; Kneubühler, Mathias; Itten, Klaus I.

2008-01-01

In spectrodirectional Remote Sensing (RS) the Earth's surface reflectance characteristics are studied by means of their angular dimensions. Almost all natural surfaces exhibit an individual anisotropic reflectance behaviour due to the contrast between the optical properties of surface elements and background and the geometric surface properties of the observed scene. The underlying concept, which describes the reflectance characteristic of a specific surface area, is called the bidirectional reflectance distribution function (BRDF). BRDF knowledge is essential for both correction of directional effects in RS data and quantitative retrieval of surface parameters. Ground-based spectrodirectional measurements are usually performed with goniometer systems. An accurate retrieval of the bidirectional reflectance factors (BRF) from field goniometer measurements requires hyperspectral knowledge of the angular distribution of the reflected and the incident radiation. However, prior to the study at hand, no operational goniometer system was able to fulfill this requirement. This study presents the first dual-view field goniometer system, which is able to simultaneously collect both the reflected and the incident radiation at high angular and spectral resolution and, thus, providing the necessary spectrodirectional datasets to accurately retrieve the surface specific BRF. Furthermore, the angular distribution of the incoming diffuse radiation is characterized for various atmospheric conditions and the BRF retrieval is performed for an artificial target and compared to laboratory spectrodirectional measurement results obtained with the same goniometer system. Suggestions for further improving goniometer systems are given and the need for intercalibration of various goniometers as well as for standardizing spectrodirectional measurements is expressed. PMID:27873805

The Improved Dual-view Field Goniometer System FIGOS.

PubMed

Schopfer, Jürg; Dangel, Stefan; Kneubühler, Mathias; Itten, Klaus I

2008-08-28

In spectrodirectional Remote Sensing (RS) the Earth's surface reflectance characteristics are studied by means of their angular dimensions. Almost all natural surfaces exhibit an individual anisotropic reflectance behaviour due to the contrast between the optical properties of surface elements and background and the geometric surface properties of the observed scene. The underlying concept, which describes the reflectance characteristic of a specific surface area, is called the bidirectional reflectance distribution function (BRDF). BRDF knowledge is essential for both correction of directional effects in RS data and quantitative retrieval of surface parameters. Ground-based spectrodirectional measurements are usually performed with goniometer systems. An accurate retrieval of the bidirectional reflectance factors (BRF) from field goniometer measurements requires hyperspectral knowledge of the angular distribution of the reflected and the incident radiation. However, prior to the study at hand, no operational goniometer system was able to fulfill this requirement. This study presents the first dual-view field goniometer system, which is able to simultaneously collect both the reflected and the incident radiation at high angular and spectral resolution and, thus, providing the necessary spectrodirectional datasets to accurately retrieve the surface specific BRF. Furthermore, the angular distribution of the incoming diffuse radiation is characterized for various atmospheric conditions and the BRF retrieval is performed for an artificial target and compared to laboratory spectrodirectional measurement results obtained with the same goniometer system. Suggestions for further improving goniometer systems are given and the need for intercalibration of various goniometers as well as for standardizing spectrodirectional measurements is expressed.

Medicine Delivery Device with Integrated Sterilization and Detection

NASA Technical Reports Server (NTRS)

Sheam, Michael J.; Greer, Harold F.; Manohara, Harish

2013-01-01

Sterile delivery devices can be created by integrating a medicine delivery instrument with surfaces that are coated with germicidal and anti-fouling material. This requires that a large-surface-area template be developed within a constrained volume to ensure good contact between the delivered medicine and the germicidal material. Both of these can be integrated using JPL-developed silicon nanotip or cryo-etch black silicon technologies with atomic layer deposition (ALD) coating of specific germicidal layers. Nanofabrication techniques that are used to produce a microfluidics device are also capable of synthesizing extremely hig-hsurface-area templates in precise locations, and coating those surfaces with conformal films to manipulate their surface properties. This methodology has been successfully applied at JPL to produce patterned and coated silicon nanotips (also known as black silicon) to manipulate the hydrophilicity of surfaces to direct the spreading of fluids in microdevices. JPL s ALD technique is an ideal method to produce the highly conformal coatings required for this type of application. Certain materials, such as TiO2, have germicidal and anti-fouling properties when they are illuminated with UV light. The proposed delivery device contacts medicine with this high-surface-area black silicon surface coated with a thin-film germicidal deposited conformally with ALD. The coating can also be illuminated with ultraviolet light for the purpose of sterilization or identification of the medicine itself. This constrained volume that is located immediately prior to delivery into a patient, ensures that the medicine delivery device is inherently sterile.

The Impact of Soil Moisture Initialization On Seasonal Precipitation Forecasts

NASA Technical Reports Server (NTRS)

Koster, R. D.; Suarez, M. J.; Tyahla, L.; Houser, Paul (Technical Monitor)

2002-01-01

Some studies suggest that the proper initialization of soil moisture in a forecasting model may contribute significantly to the accurate prediction of seasonal precipitation, especially over mid-latitude continents. In order for the initialization to have any impact at all, however, two conditions must be satisfied: (1) the initial soil moisture anomaly must be "remembered" into the forecasted season, and (2) the atmosphere must respond in a predictable way to the soil moisture anomaly. In our previous studies, we identified the key land surface and atmospheric properties needed to satisfy each condition. Here, we tie these studies together with an analysis of an ensemble of seasonal forecasts. Initial soil moisture conditions for the forecasts are established by forcing the land surface model with realistic precipitation prior to the start of the forecast period. As expected, the impacts on forecasted precipitation (relative to an ensemble of runs that do not utilize soil moisture information) tend to be localized over the small fraction of the earth with all of the required land and atmosphere properties.

In vivo degradation of polyethylene liners after gamma sterilization in air.

PubMed

Kurtz, Steven M; Rimnac, Clare M; Hozack, William J; Turner, Joseph; Marcolongo, Michele; Goldberg, Victor M; Kraay, Matthew J; Edidin, Avram A

2005-04-01

Ultra-high molecular weight polyethylene degrades during storage in air following gamma sterilization, but the extent of in vivo degradation remains unclear. The purpose of this study was to quantify the extent to which the mechanical properties and oxidation of conventional polyethylene acetabular liners treated with gamma sterilization in air change in vivo. Fourteen modular cementless acetabular liners were revised at an average of 10.3 years (range, 5.9 to 13.5 years) after implantation. All liners, which had been machined from GUR 415 resin, had been gamma-sterilized in air; the average shelf life was 0.3 year (range, 0.0 to 0.8 year). After removal, the components were expeditiously frozen to minimize ex vivo changes to the polyethylene prior to characterization. The average duration between freezing and testing was 0.6 year. Mechanical properties and oxidation were measured with use of the small-punch test and Fourier transform infrared spectroscopy, respectively, in the loaded and unloaded regions of the liners. There was substantial regional variation in the mechanical properties and oxidation of the retrieved liners. The ultimate load was observed to vary by >90% near the surface. On the average, the rim and the unloaded bearing showed evidence of severe oxidation near the surface after long-term in vivo aging, but these trends were not typically observed on the loaded bearing surface or near the backside of the liners. The mechanical properties of polyethylene that has been gamma-sterilized in air may decrease substantially in vivo, depending on the location in the liner. The most severe oxidation was observed at the rim, suggesting that the femoral head inhibits access of oxygen-containing body fluids to the bearing surface. This is perhaps why in vivo oxidation has not been associated with clinical performance to date.

Impact of cleaning methods on the structural properties and morphology of SrTiO3 surface

NASA Astrophysics Data System (ADS)

Arnay, Iciar; Rubio-Zuazo, Juan; Castro, German R.

2018-01-01

SrTiO3 is a widely used substrate for the epitaxial growth of complex systems. Nevertheless, in order to get good quality interface and avoid the formation of defects in the adsorbed layer it is essential to prepare the surface of the substrate prior to the deposition. Thermal and chemical treatments are mostly used to eliminate superficial contamination and improve the surface quality. However, there is a lack of information regarding the impact of these treatments on the formation of structural defects at the SrTiO3 surface. In this work we present a detailed characterization of the SrTiO3 surface for the different cleaning methods paying special attention to the formation of oxygen vacancies, large surface mosaicity and roughness. We prove that thermal treatment induces large surface roughness and that chemical etching produces important structural defects at the surface. Our results show that mechanical polishing provided the best compromise in terms of large surface domains, low roughness, absence of oxygen vacancies and absence of atomic structure modification, although with the presence of low level of contaminants at the SrTiO3 surface.

41 CFR 102-36.270 - What if a federal agency requests personal property that is undergoing donation screening or in...

Code of Federal Regulations, 2010 CFR

2010-07-01

... requests personal property that is undergoing donation screening or in the sales process? 102-36.270... agency requests personal property that is undergoing donation screening or in the sales process? Prior to... property undergoing donation screening or in the sales process. Federal transfers may be authorized prior...

41 CFR 102-36.270 - What if a federal agency requests personal property that is undergoing donation screening or in...

Code of Federal Regulations, 2012 CFR

2012-01-01

... requests personal property that is undergoing donation screening or in the sales process? 102-36.270... agency requests personal property that is undergoing donation screening or in the sales process? Prior to... property undergoing donation screening or in the sales process. Federal transfers may be authorized prior...

41 CFR 102-36.270 - What if a federal agency requests personal property that is undergoing donation screening or in...

Code of Federal Regulations, 2014 CFR

2014-01-01

... requests personal property that is undergoing donation screening or in the sales process? 102-36.270... agency requests personal property that is undergoing donation screening or in the sales process? Prior to... property undergoing donation screening or in the sales process. Federal transfers may be authorized prior...

41 CFR 102-36.270 - What if a federal agency requests personal property that is undergoing donation screening or in...

Code of Federal Regulations, 2013 CFR

2013-07-01

... requests personal property that is undergoing donation screening or in the sales process? 102-36.270... agency requests personal property that is undergoing donation screening or in the sales process? Prior to... property undergoing donation screening or in the sales process. Federal transfers may be authorized prior...

41 CFR 102-36.270 - What if a federal agency requests personal property that is undergoing donation screening or in...

Code of Federal Regulations, 2011 CFR

2011-01-01

... requests personal property that is undergoing donation screening or in the sales process? 102-36.270... agency requests personal property that is undergoing donation screening or in the sales process? Prior to... property undergoing donation screening or in the sales process. Federal transfers may be authorized prior...

Finite Size Effects in Submonolayer Catalysts Investigated by CO Electrosorption on PtsML/Pd(100).

PubMed

Yuan, Qiuyi; Doan, Hieu A; Grabow, Lars C; Brankovic, Stanko R

2017-10-04

A combination of scanning tunneling microscopy, subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS), and density functional theory (DFT) is used to quantify the local strain in 2D Pt clusters on the 100 facet of Pd and its effect on CO chemisorption. Good agreement between SNIFTIRS experiments and DFT simulations provide strong evidence that, in the absence of coherent strain between Pt and Pd, finite size effects introduce local compressive strain, which alters the chemisorption properties of the surface. Though this effect has been widely neglected in prior studies, our results suggest that accurate control over cluster sizes in submonolayer catalyst systems can be an effective approach to fine-tune their catalytic properties.

An overview of zirconia ceramics: basic properties and clinical applications.

PubMed

Manicone, Paolo Francesco; Rossi Iommetti, Pierfrancesco; Raffaelli, Luca

2007-11-01

Zirconia (ZrO2) is a ceramic material with adequate mechanical properties for manufacturing of medical devices. Zirconia stabilized with Y2O3 has the best properties for these applications. When a stress occurs on a ZrO2 surface, a crystalline modification opposes the propagation of cracks. Compression resistance of ZrO2 is about 2000 MPa. Orthopedic research led to this material being proposed for the manufacture of hip head prostheses. Prior to this, zirconia biocompatibility had been studied in vivo; no adverse responses were reported following the insertion of ZrO2 samples into bone or muscle. In vitro experimentation showed absence of mutations and good viability of cells cultured on this material. Zirconia cores for fixed partial dentures (FPD) on anterior and posterior teeth and on implants are now available. Clinical evaluation of abutments and periodontal tissue must be performed prior to their use. Zirconia opacity is very useful in adverse clinical situations, for example, for masking of dischromic abutment teeth. Radiopacity can aid evaluation during radiographic controls. Zirconia frameworks are realized by using computer-aided design/manufacturing (CAD/CAM) technology. Cementation of Zr-ceramic restorations can be performed with adhesive luting. Mechanical properties of zirconium oxide FPDs have proved superior to those of other metal-free restorations. Clinical evaluations, which have been ongoing for 3 years, indicate a good success rate for zirconia FPDs. Zirconia implant abutments can also be used to improve the aesthetic outcome of implant-supported rehabilitations. Newly proposed zirconia implants seem to have good biological and mechanical properties; further studies are needed to validate their application.

Perception-based 3D tactile rendering from a single image for human skin examinations by dynamic touch.

PubMed

Kim, K; Lee, S

2015-05-01

Diagnosis of skin conditions is dependent on the assessment of skin surface properties that are represented by more tactile properties such as stiffness, roughness, and friction than visual information. Due to this reason, adding tactile feedback to existing vision based diagnosis systems can help dermatologists diagnose skin diseases or disorders more accurately. The goal of our research was therefore to develop a tactile rendering system for skin examinations by dynamic touch. Our development consists of two stages: converting a single image to a 3D haptic surface and rendering the generated haptic surface in real-time. Converting to 3D surfaces from 2D single images was implemented with concerning human perception data collected by a psychophysical experiment that measured human visual and haptic sensibility to 3D skin surface changes. For the second stage, we utilized real skin biomechanical properties found by prior studies. Our tactile rendering system is a standalone system that can be used with any single cameras and haptic feedback devices. We evaluated the performance of our system by conducting an identification experiment with three different skin images with five subjects. The participants had to identify one of the three skin surfaces by using a haptic device (Falcon) only. No visual cue was provided for the experiment. The results indicate that our system provides sufficient performance to render discernable tactile rendering with different skin surfaces. Our system uses only a single skin image and automatically generates a 3D haptic surface based on human haptic perception. Realistic skin interactions can be provided in real-time for the purpose of skin diagnosis, simulations, or training. Our system can also be used for other applications like virtual reality and cosmetic applications. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Active Prior Tactile Knowledge Transfer for Learning Tactual Properties of New Objects

PubMed Central

Feng, Di

2018-01-01

Reusing the tactile knowledge of some previously-explored objects (prior objects) helps us to easily recognize the tactual properties of new objects. In this paper, we enable a robotic arm equipped with multi-modal artificial skin, like humans, to actively transfer the prior tactile exploratory action experiences when it learns the detailed physical properties of new objects. These experiences, or prior tactile knowledge, are built by the feature observations that the robot perceives from multiple sensory modalities, when it applies the pressing, sliding, and static contact movements on objects with different action parameters. We call our method Active Prior Tactile Knowledge Transfer (APTKT), and systematically evaluated its performance by several experiments. Results show that the robot improved the discrimination accuracy by around 10% when it used only one training sample with the feature observations of prior objects. By further incorporating the predictions from the observation models of prior objects as auxiliary features, our method improved the discrimination accuracy by over 20%. The results also show that the proposed method is robust against transferring irrelevant prior tactile knowledge (negative knowledge transfer). PMID:29466300

Solid-on-solid contact in a sphere-wall collision in a viscous fluid

NASA Astrophysics Data System (ADS)

Birwa, Sumit Kumar; Rajalakshmi, G.; Govindarajan, Rama; Menon, Narayanan

2018-04-01

We study experimentally the collision between a sphere falling through a viscous fluid and a solid plate below. It is known that there is a well-defined threshold Stokes number above which the sphere rebounds from such a collision. Our experiment tests for direct contact between the colliding bodies and, contrary to prior theoretical predictions, shows that solid-on-solid contact occurs even for Stokes numbers just above the threshold for rebounding. The dissipation is fluid dominated, though details of the contact mechanics depend on the surface and bulk properties of the solids. Our experiments and a model calculation indicate that mechanical contact between the two colliding objects is generic and will occur for any realistic surface roughness.

Friction behavior of 304 stainless steel of varying hardness lubricated with benzene and some benzyl structures

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1974-01-01

The lubricating properties of some benzyl and benzene structures were determined by using 304 stainless steel surfaces strained to various hardness. Friction coefficients and wear track widths were measured with a Bowden-Leben type friction apparatus by using a pin-on-disk specimen configuration. Results obtained indicate that benzyl monosulfide, dibenzyl disulfide, and benzyl alcohol resulted in the lowest friction coefficients for 304 stainless steel, while benzyl ether provided the least surface protection and gave the highest friction. Strainhardening of the 304 stainless steel prior to sliding resulted in reduced friction in dry sliding. With benzyl monosulfide, dibenzyl disulfide, and benzyl alcohol changes in 304 stainless steel hardness had no effect upon friction behavior.

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

Cai, Chang-Yun; Yang, Hongta, E-mail: hyang@dragon.nchu.edu.tw; Lin, Kun-Yi Andrew

This article reports a scalable technology for fabricating polymer films with excellent water-repelling and anti-ultraviolet properties. A roll-to-roll compatible doctor blade coating technology is utilized to prepare silica colloidal crystal-polymer composites. The silica microspheres can then be selectively removed to create flexible self-standing macroporous polymer films with crystalline arrays of pores. The void sizes are controlled by tuning the duration of a reactive ion etching process prior to the removal of the templating silica microspheres. After surface modification, superhydrophobic surface can be achieved. This study further demonstrates that the as-prepared transparent porous films with 200 nm of pores exhibit diffraction ofmore » ultraviolet lights originated from the Bragg's diffractive of light from the three-dimensional highly ordered air cavities.« less

Innate Immunity and Biomaterials at the Nexus: Friends or Foes.

PubMed

Christo, Susan N; Diener, Kerrilyn R; Bachhuka, Akash; Vasilev, Krasimir; Hayball, John D

2015-01-01

Biomaterial implants are an established part of medical practice, encompassing a broad range of devices that widely differ in function and structural composition. However, one common property amongst biomaterials is the induction of the foreign body response: an acute sterile inflammatory reaction which overlaps with tissue vascularisation and remodelling and ultimately fibrotic encapsulation of the biomaterial to prevent further interaction with host tissue. Severity and clinical manifestation of the biomaterial-induced foreign body response are different for each biomaterial, with cases of incompatibility often associated with loss of function. However, unravelling the mechanisms that progress to the formation of the fibrotic capsule highlights the tightly intertwined nature of immunological responses to a seemingly noncanonical "antigen." In this review, we detail the pathways associated with the foreign body response and describe possible mechanisms of immune involvement that can be targeted. We also discuss methods of modulating the immune response by altering the physiochemical surface properties of the biomaterial prior to implantation. Developments in these areas are reliant on reproducible and effective animal models and may allow a "combined" immunomodulatory approach of adapting surface properties of biomaterials, as well as treating key immune pathways to ultimately reduce the negative consequences of biomaterial implantation.

Quantitative examination of demineralized and remineralized dental lesions using photothermal radiometry and modulated luminescence

NASA Astrophysics Data System (ADS)

Hellen, Adam; Mandelis, Andreas; Finer, Yoav; Amaechi, Bennett

2010-02-01

The development of photothermal techniques to detect thermal waves in biological tissue has occurred with a concomitant advancement in the extraction of material thermophysical properties and knowledge regarding the internal structure of a medium. Human molars (n=37) were subjected to demineralization in acid gel (pH 4.5, 10 days), followed by incubation in different fluoride-containing remineralization solutions. PTR-LUM frequency scans (1 Hz - 1 kHz) were performed prior to and during demineralization and remineralization treatments. Transverse Micro-Radiography (TMR) analysis followed at treatment conclusion. A coupled diffuse-photon-density-wave and thermal-wave theoretical model was used to quantitatively evaluate changes in thermal and optical properties of sound, demineralized and remineralized enamel. Amplitude increase and phase lag decrease in demineralized samples were consistent with higher scatter of the diffuse-photon density field and thermal wave confinement to near-surface regions. A remineralized sample illustrates a complex interplay between surface and subsurface processes, confining the thermal-wave centroid toward the dominating layer. PTR-LUM sensitivity to changes in tooth mineralization coupled with optical and thermal property extraction illustrates the technique's potential for non-destructive evaluation of multi-layered turbid media.

Morphological properties of collagen fibers in porcine lamina propria

PubMed Central

Johanes, Iecun; Mihelc, Elaine; Sivasankar, Mahalakshmi; Ivanisevic, Albena

2009-01-01

Objectives Collagen influences the biomechanical properties of vocal folds. Altered collagen morphology has been implicated in dysphonia associated with aging and scarring. Documenting the morphological properties of native collagen in healthy vocal folds is essential to understand the structural and functional alterations to collagen with aging and disease. Our primary objective was to quantify the morphological properties of collagen in the vocal fold lamina propria. Our secondary exploratory objective was to investigate the effects of pepsin exposure on the morphological properties of collagen in the lamina propria. Design Experimental, in vitro study with porcine model. Methods Lamina propria was dissected from 26 vocal folds and imaged with Atomic Force Microscopy (AFM). Morphological data on d-periodicity, diameter, and roughness of collagen fibers were obtained. To investigate the effects of pepsin exposure on collagen morphology, vocal fold surface was exposed to pepsin or sham challenge prior to lamina propria dissection and AFM imaging. Results The d-periodicity, diameter, and roughness values for native vocal fold collagen are consistent with literature reports for collagen fibers in other body tissue. Pepsin exposure on vocal fold surface did not appear to change the morphological properties of collagen fibers in the lamina propria. Conclusions Quantitative data on collagen morphology were obtained at nanoscale resolution. Documenting collagen morphology in healthy vocal folds is critical for understanding the physiological changes to collagen with aging and scarring, and for designing biomaterials that match the native topography of lamina propria. PMID:20171830

Climate effects caused by land plant invasion in the Devonian

NASA Astrophysics Data System (ADS)

Hir guillaume, Le; yannick, Donnadieu; yves, Goddéris; brigitte, Meyer-Berthaud; gilles, Ramstein

2017-04-01

Land plants invaded continents during the Mid-Paleozoic. Their spreading and diversification have been compared to the Cambrian explosion in terms of intensity and impact on the diversification of life on Earth. Whereas prior studies were focused on the evolution of the root system and its weathering contribution, here we investigated the biophysical impacts of plant colonization on the surface climate through changes in continental albedo, roughness, thermal properties, and potential evaporation using a 3D-climate model coupled to a global biogeochemical cycles associated to a simple model for vegetation dynamics adapted to Devonian conditions. From the Early to the Late Devonian, we show that continental surface changes induced by land plants and tectonic drift have produced a large CO2 drawdown without being associated to a global cooling, because the cooling trend is counteracted by a warming trend resulting from the surface albedo reduction. If CO2 is consensually assumed as the main driver of the Phanerozoic climate, during land-plant invasion, the modifications of soil properties could have played in the opposite direction of the carbon dioxide fall, hence maintaining warm temperatures during part of the Devonian.

PHOBOS Exploration using Two Small Solar Electric Propulsion Spacecraft

NASA Technical Reports Server (NTRS)

Lang, Jared J.; Baker, John D.; Castillo-Rogez, Julie C.; McElrath, Timothy P.; Piacentine, Jamie S.; Snyder, J. Steve

2012-01-01

Primitive bodies are exciting targets for exploration as they provide clues to the early Solar system conditions and dynamical evolution. The two moons of Mars are particularly interesting because of their proximity to an astrobiological target. However, after four decades of Mars exploration, their origin and nature remain enigmatic. In addition, when considering the long-term objectives of the flexible path for the potential human exploration to Mars, Phobos and Deimos present exciting intermediate opportunities without the complication and expense of landing and ascending from the surface. As interest in these targets for the next frontier of human exploration grows, characterization missions designed specifically to examine surface properties, landing environments, and surface mapping prior to human exploration are becoming increasingly important. A precursor mission concept of this sort has been developed using two identical spacecraft designed from low cost, flight proven and certified off-the-shelf component and utilizing Solar Electric Propulsion (SEP) to orbit both targets as secondary payloads launched aboard any NASA or GTO launch. This precursor mission has the potential to address both precursor measurements that are strategic knowledge gaps and decadal science, including soil physical properties at the global and local (human) scale and the search for in situ resources.

Quantifying Arctic Terrestrial Environment Behaviors Using Geophysical, Point-Scale and Remote Sensing Data

NASA Astrophysics Data System (ADS)

Dafflon, B.; Hubbard, S. S.; Ulrich, C.; Peterson, J. E.; Wu, Y.; Wainwright, H. M.; Gangodagamage, C.; Kholodov, A. L.; Kneafsey, T. J.

2013-12-01

Improvement in parameterizing Arctic process-rich terrestrial models to simulate feedbacks to a changing climate requires advances in estimating the spatiotemporal variations in active layer and permafrost properties - in sufficiently high resolution yet over modeling-relevant scales. As part of the DOE Next-Generation Ecosystem Experiments (NGEE-Arctic), we are developing advanced strategies for imaging the subsurface and for investigating land and subsurface co-variability and dynamics. Our studies include acquisition and integration of various measurements, including point-based, surface-based geophysical, and remote sensing datasets These data have been collected during a series of campaigns at the NGEE Barrow, AK site along transects that traverse a range of hydrological and geomorphological conditions, including low- to high- centered polygons and drained thaw lake basins. In this study, we describe the use of galvanic-coupled electrical resistance tomography (ERT), capacitively-coupled resistivity (CCR) , permafrost cores, above-ground orthophotography, and digital elevation model (DEM) to (1) explore complementary nature and trade-offs between characterization resolution, spatial extent and accuracy of different datasets; (2) develop inversion approaches to quantify permafrost characteristics (such as ice content, ice wedge frequency, and presence of unfrozen deep layer) and (3) identify correspondences between permafrost and land surface properties (such as water inundation, topography, and vegetation). In terms of methods, we developed a 1D-based direct search approach to estimate electrical conductivity distribution while allowing exploration of multiple solutions and prior information in a flexible way. Application of the method to the Barrow datasets reveals the relative information content of each dataset for characterizing permafrost properties, which shows features variability from below one meter length scales to large trends over more than a kilometer. Further, we used Pole- and Kite-based low-altitude aerial photography with inferred DEM, as well as DEM from LiDAR dataset, to quantify land-surface properties and their co-variability with the subsurface properties. Comparison of the above- and below-ground characterization information indicate that while some permafrost characteristics correspond with changes in hydrogeomorphological expressions, others features show more complex linkages with landscape properties. Overall, our results indicate that remote sensing data, point-scale measurements and surface geophysical measurements enable the identification of regional zones having similar relations between subsurface and land surface properties. Identification of such zonation and associated permafrost-land surface properties can be used to guide investigations of carbon cycling processes and for model parameterization.

Durable anti-fogging effect and adhesion improvement on polymer surfaces

NASA Astrophysics Data System (ADS)

Moser, E. M.; Gilliéron, D.; Henrion, G.

2010-01-01

The hydrophobic properties of polymeric surfaces may cause fogging in transparent packaging and poor adhesion to printing colours and coatings. Novel plasma processes for durable functionalization of polypropylene and polyethylene terephthalate substrates were developed and analysed using optical emission spectroscopy. A worm-like nano pattern was created on the polypropylene surface prior to the deposition of thin polar plasma polymerised layers. For both substrates, highly polar surfaces exhibiting a surface tension of up to 69 mN/m and a water contact angle of about 10° were produced - providing the anti-fogging effect. The deposition of thin plasma polymerised layers protects the increased surface areas and enables to tailoring the surface energy of the substrate in a wide range. Wetting characteristics were determined by dynamic contact angle measurements. Investigations of the chemical composition of several layers using X-ray photoelectron spectroscopy and FT-infrared spectroscopy were correlated with functional testing. The surface topography was investigated using atomic force microscopy. The weldability and peeling-off characteristics of the plasma treated polymer films could be adjusted by varying the process parameters. Global and specific migration analyses were undertaken in order to ensure the manufacturing of plasma treated polymer surfaces for direct food contact purposes.

Neuromuscular strategies for the transitions between level and hill surfaces during walking

PubMed Central

Gottschall, Jinger S.; Nichols, T. Richard

2011-01-01

Despite continual fluctuations in walking surface properties, humans and animals smoothly transition between terrains in their natural surroundings. Walking transitions have the potential to influence dynamic balance in both the anterior–posterior and medial–lateral directions, thereby increasing fall risk and decreasing mobility. The goal of the current manuscript is to provide a review of the literature that pertains to the topic of surface slope transitions between level and hill surfaces, as well as report the recent findings of two experiments that focus on the neuromuscular strategies of surface slope transitions. Our results indicate that in anticipation of a change in surface slope, neuromuscular patterns during level walking prior to a hill are significantly different from the patterns during level walking without the future change in surface. Typically, the changes in muscle activity were due to co-contraction of opposing muscle groups and these changes correspond to modifications in head pitch. In addition, further experiments revealed that the neck proprioceptors may be an initial source of feedback for upcoming surface slope transitions. Together, these results illustrate that in order to safely traverse varying surfaces, transitions strides are functionally distinct from either level walking or hill walking independently. PMID:21502127

Physicochemical characterisation of fluids and soft foods frequently mixed with oral drug formulations prior to administration to children.

PubMed

Kersten, E; Barry, A; Klein, S

2016-03-01

Oral drug administration to children poses specific pharmaceutical challenges that are often not seen to the same extent in adults, and whose occurrence may also be age dependent. When an age-appropriate dosage form is not available, manipulation of adult dosage forms (e.g., splitting and crushing of tablets or opening of capsules) has been reported as a means to facilitate administration to children. To enhance swallowability and/or mask an unpleasant taste of the dosage form to be administered, crushed/split tablets or the contents of capsules are often mixed with food or drinks or suspended in a vehicle prior to administration. However, it seems that the risks and benefits of an approach whereby the dosage form is modified prior to administration in this manner are everything but clear. The aim of the present study was to gain an overview of the physicochemical properties of a number of fluids, soft foods and suspension vehicles that are commonly reported to be mixed with oral medications before administration to children to improve patient acceptability. For this purpose, physicochemical parameters of 15 different fluids, soft foods and suspension vehicles were measured. These included pH, buffer capacity, osmolality, surface tension and viscosity. Results of the study clearly show the differences in physicochemical properties of the test candidates. It is thus obvious that the type of fluid/food mixed with a drug product before administration may have a significant impact on bioavailability of the drug administered. Therefore, a risk-based assessment of such practices considering API properties, formulation features and physicochemical properties of the fluids and foods intended to be co-administered with the dosage form, in conjunction with the anatomical and physiological maturity of the gastro-intestinal tract in the intended paediatric population, should be an essential part of paediatric oral formulation development.

Assessment of climate variability of the Greenland Ice Sheet: Integration of in situ and satellite data

NASA Technical Reports Server (NTRS)

Steffen, K.; Abdalati, W.; Stroeve, J.; Key, J.

1994-01-01

The proposed research involves the application of multispectral satellite data in combination with ground truth measurements to monitor surface properties of the Greenland Ice Sheet which are essential for describing the energy and mass of the ice sheet. Several key components of the energy balance are parameterized using satellite data and in situ measurements. The analysis will be done for a ten year time period in order to get statistics on the seasonal and interannual variations of the surface processes and the climatology. Our goal is to investigate to what accuracy and over what geographic areas large scale snow properties and radiative fluxes can be derived based upon a combination of available remote sensing and meteorological data sets. Operational satellite sensors are calibrated based on ground measurements and atmospheric modeling prior to large scale analysis to ensure the quality of the satellite data. Further, several satellite sensors of different spatial and spectral resolution are intercompared to access the parameter accuracy. Proposed parameterization schemes to derive key component of the energy balance from satellite data are validated. For the understanding of the surface processes a field program was designed to collect information on spectral albedo, specular reflectance, soot content, grain size and the physical properties of different snow types. Further, the radiative and turbulent fluxes at the ice/snow surface are monitored for the parameterization and interpretation of the satellite data. The expected results include several baseline data sets of albedo, surface temperature, radiative fluxes, and different snow types of the entire Greenland Ice Sheet. These climatological data sets will be of potential use for climate sensitivity studies in the context of future climate change.

An evaluation of the interfacial bond properties between carbon phenolic and glass phenolic composites

NASA Technical Reports Server (NTRS)

Jordan, Kelvin; Clinton, Raymond; Jeelani, Shaik

1989-01-01

The effects of moisture and surface finish on the mechanical and physical properties of the interfacial bond between the carbon/phenolic (C/P) and glass/phenolic (G/P) composite materials are presented. Four flat panel laminates were fabricated using the C/P and G/P materials. Of the four laminates, one panel was fabricated in which the C/P and G/P materials were cured simultaneously. It was identified as the cocure. The remaining laminates were processed with an initial simultaneous cure of the three C/P billets. Two surface finishes, one on each half, were applied to the top surface. Prior to the application and cure of the G/P material to the machined surface of the three C/P panels, each was subjected to the specific environmental conditioning. Types of conditioning included: (1) nominal fabrication environment, (2) a prescribed drying cycle, and (3) a total immersion in water at 160 F. Physical property tests were performed on specimens removed from the C/P materials of each laminate for determination of the specific gravity, residual volatiles and and resin content. Comparisons of results with shuttle solid rocket motor (SRM) nozzle material specifications verified that the materials used in fabricating the laminates met acceptance criteria and were representative of SRM nozzle materials. Mechanical property tests were performed at room temperature on specimens removed from the G/P, the C/P and the interface between the two materials for each laminate. The double-notched shear strength test was used to determine the ultimate interlaminar shear strength. Results indicate no appreciable difference in the C/P material of the four laminates with the exception of the cocure laminate, where 20 percent reduction in the strength was observed. The most significant effect and the ultimate strength was significantly reduced in the wet material. No appreciable variation was noted between the surface finishes in the wet laminate.

Ion Exchange Equilibrium and Kinetic Properties of Polyacrylate Films and Applications to Chemical Analysis and Environmental Decontamination

NASA Technical Reports Server (NTRS)

Tanner, Stephen P.

1997-01-01

One of the goals of the original proposal was to study how cross-linking affects the properties of an ion exchange material(IEM) developed at Lewis Research Center. However, prior to the start of this work, other workers at LERC investigated the effect of cross-linking on the properties of this material. Other than variation in the ion exchange capacity, the chemical characteristics were shown to be independent of the cross-linking agent, and the degree of cross-linking. New physical forms of the film were developed (film, supported film, various sizes of beads, and powder). All showed similar properties with respect to ion exchange equilibria but the kinetics of ion exchange depended on the surface area per unit mass; the powder form of the IEM exchanging much more rapidly than the other forms. The research performed under this grant was directed towards the application of the IEM to the analysis of metal ions at environmental concentrations.

Modeling Images of Natural 3D Surfaces: Overview and Potential Applications

NASA Technical Reports Server (NTRS)

Jalobeanu, Andre; Kuehnel, Frank; Stutz, John

2004-01-01

Generative models of natural images have long been used in computer vision. However, since they only describe the of 2D scenes, they fail to capture all the properties of the underlying 3D world. Even though such models are sufficient for many vision tasks a 3D scene model is when it comes to inferring a 3D object or its characteristics. In this paper, we present such a generative model, incorporating both a multiscale surface prior model for surface geometry and reflectance, and an image formation process model based on realistic rendering, the computation of the posterior model parameter densities, and on the critical aspects of the rendering. We also how to efficiently invert the model within a Bayesian framework. We present a few potential applications, such as asteroid modeling and Planetary topography recovery, illustrated by promising results on real images.

Segregation effects during solidification in weightless melts

NASA Technical Reports Server (NTRS)

Li, C.

1973-01-01

Two types of melt segregation effects were studied: (1) evaporative segregation, or segregation due to surface evaporation; and (2) freezing segregation, or segregation due to liquid-solid phase transformation. These segregation effects are closely related. In fact, evaporative segregation always precedes freezing segregation to some degree and must often be studied prior to performing meaningful solidification experiments. This is particularly true since evaporation may cause the melt composition, at least at the critical surface regions or layers to be affected manyfold within seconds so that the surface region or layer melting point and other thermophysical properties, nucleation characteristics, base for undercooling, and critical velocity to avoid constitutional supercooling, may be completely unexpected. An important objective was, therefore, to develop the necessary normal evaporation equations for predicting the compositional changes within specified times at temperature and to correlate these equations with actual experimental data collected from the literature.

The Role of Ru Redox in pH-Dependent Oxygen Evolution on Rutile Ruthenium Dioxide Surfaces

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

Stoerzinger, Kelsey A.; Rao, Reshma R.; Wang, Xiao Renshaw

Rutile RuO 2 is known to exhibit high catalytic activity for the oxygen evolution reaction (OER) and large pseudocapacitance associated with redox of surface Ru, however the mechanistic link between these properties and the role of pH is yet to be understood. Here we report that the OER activities of the (101), (001) and (111) RuO 2 surfaces were found to increase while the potential of a pseudocapacitive feature just prior to OER shifted to lower potentials (“super-Nernstian” shift) with increasing pH on the reversible hydrogen electrode (RHE) scale. This behavior is in contrast to the (100) and (110) surfacesmore » that have pH-independent Ru redox and OER activity. The link in catalytic and pseudocapacitive behavior illustrates the importance of this redox feature in generating active sites, building new mechanistic understanding of the OER.« less

Impact of fluorine based reactive chemistry on structure and properties of high moment magnetic material

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

Yang, Xiaoyu, E-mail: xiaoyu.yang@wdc.com; Chen, Lifan; Han, Hongmei

The impact of the fluorine-based reactive ion etch (RIE) process on the structural, electrical, and magnetic properties of NiFe and CoNiFe-plated materials was investigated. Several techniques, including X-ray fluorescence, 4-point-probe, BH looper, transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS), were utilized to characterize both bulk film properties such as thickness, average composition, Rs, ρ, Bs, Ms, and surface magnetic “dead” layers' properties such as thickness and element concentration. Experimental data showed that the majority of Rs and Bs changes of these bulk films were due to thickness reduction during exposure to the RIE process. ρ and Msmore » change after taking thickness reduction into account were negligible. The composition of the bulk films, which were not sensitive to surface magnetic dead layers with nano-meter scale, showed minimum change as well. It was found by TEM and EELS analysis that although both before and after RIE there were magnetic dead layers on the top surface of these materials, the thickness and element concentration of the layers were quite different. Prior to RIE, dead layer was actually native oxidation layers (about 2 nm thick), while after RIE dead layer consisted of two sub-layers that were about 6 nm thick in total. Sub-layer on the top was native oxidation layer, while the bottom layer was RIE “damaged” layer with very high fluorine concentration. Two in-situ RIE approaches were also proposed and tested to remove such damaged sub-layers.« less

Transient Flow through an Unsaturated Levee Embankment during the 2011 Mississippi River Flood

NASA Astrophysics Data System (ADS)

Jafari, N.; Stark, T.; Vahedifard, F.; Cadigan, J.

2017-12-01

The Mississippi River and corresponding tributaries drain approximately 3.23 million km2 (1.25 million mi2) or the equivalent of 41% of the contiguous United States. Approximately 2,600 km ( 1,600 miles) of earthen levees presently protect major urban cities and agricultural land against the periodic Mississippi River floods within the Lower Mississippi River Valley. The 2011 flood also severely stressed the levees and highlighted the need to evaluate the behavior of levee embankments during high water levels. The performance of earthen levees is complex because of the uncertainties in construction materials, antecedent moisture contents, hydraulic properties, and lack of field monitoring. In particular, calibration of unsaturated and saturated soil properties of levee embankment and foundation layers along with the evaluation of phreatic surface during high river stage is lacking. Due to the formation of sand boils at the Duncan Point Levee in Baton Rouge, LA during the 2011 flood event, a reconnaissance survey was conducted to collect pore-water pressures in the sand foundation using piezometers and identifying the phreatic surface at the peak river level. Transient seepage analyses were performed to calibrate the foundation and levee embankment material properties using field data collected. With this calibrated levee model, numerical experiments were conducted to characterize the effects of rainfall intensity and duration, progression of phreatic surface, and seasonal climate variability prior to floods on the performance of the levee embankment. For example, elevated phreatic surface from river floods are maintained for several months and can be compounded with rainfall to lead to slope instability.

Detection of hazardous cavities with combined geophysical methods

NASA Astrophysics Data System (ADS)

Hegymegi, Cs.; Nyari, Zs.; Pattantyus-Abraham, M.

2003-04-01

Unknown near-surface cavities often cause problems for municipal communities all over the world. This is the situation in Hungary in many towns and villages, too. Inhabitants and owners of real estates (houses, cottages, lands) are responsible for the safety and stability of their properties. The safety of public sites belongs to the local municipal community. Both (the owner and the community) are interested in preventing accidents. Near-surface cavities (unknown caves or earlier built and forgotten cellars) usually can be easily detected by surface geophysical methods. Traditional and recently developed measuring techniques in seismics, geoelectrics and georadar are suitable for economical investigation of hazardous, potentially collapsing cavities, prior to excavation and reinforcement. This poster will show some example for detection of cellars and caves being dangerous for civil population because of possible collapse under public sites (road, yard, playground, agricultural territory, etc.). The applied and presented methods are ground penetrating radar, seismic surface tomography and analysis of single traces, geoelectric 2D and 3D resistivity profiling. Technology and processing procedure will be presented.

Fabrication of TiO2-modified polytetrafluoroethylene ultrafiltration membranes via plasma-enhanced surface graft pretreatment

NASA Astrophysics Data System (ADS)

Qian, Yingjia; Chi, Lina; Zhou, Weili; Yu, Zhenjiang; Zhang, Zhongzhi; Zhang, Zhenjia; Jiang, Zheng

2016-01-01

Surface hydrophilic modification of polymer ultrafiltration membrane using metal oxide represents an effective yet highly challenging solution to improve water flux and antifouling performance. Via plasma-enhanced graft of poly acryl acid (PAA) prior to coating TiO2, we successfully fixed TiO2 functional thin layer on super hydrophobic polytetrafluoroethylene (PTFE) ultrafiltration (UF) membranes. The characterization results evidenced TiO2 attached on the PTFE-based UF membranes through the chelating bidentate coordination between surface-grafted carboxyl group and Ti4+. The TiO2 surface modification may greatly reduce the water contact angle from 115.8° of the PTFE membrane to 35.0° without degradation in 30-day continuous filtration operations. The novel TiO2/PAA/PTFE membranes also exhibited excellent antifouling and self-cleaning performance due to the intrinsic hydrophilicity and photocatalysis properties of TiO2, which was further confirmed by the photo-degradation of MB under Xe lamp irradiation.

Correcting Borehole Temperture Profiles for the Effects of Postglacial Warming

NASA Astrophysics Data System (ADS)

Rath, V.; Gonzalez-Rouco, J. F.

2010-09-01

Though the investigation of observed borehole temperatures has proved to be a valuable tool for the reconstruction of ground surface temperature histories, there are many open questions concerning the signifcance and accuracy of the reconstructions from these data. In particular, the temperature signal of the warming after the Last glacial Maximum (LGM) is still present in borehole temperature proiles. It also influences the relatively shallow boreholes used in current paleoclimate inversions to estimate temperature changes in the last centuries. This is shown using Monte Carlo experiments on past surface temperature change, using plausible distributions for the most important parameters, i.e.,amplitude and timing of the glacial-interglacial transition, the prior average temperature, and petrophysical properties. It has been argued that the signature of the last glacial-interglacial transition could be responsible for the high amplitudes of millennial temperature reconstructions. However, in shallow boreholes the additional effect of past climate can reasonably approximated by a linear variation of temperature with depth, and thus be accommodated by a "biased" background heat flow. This is good news for borehole climatology. A simple correction based on subtracting an appropriate prior surface temperature history shows promising results reducing these errors considerably, in particular with deeper boreholes, where the warming signal in heat flow can no longer be approximated linearly. We will show examples from North America and Eurasia, comparing temperatures reduced the proposed algoritm with AOGCM modeling results.

Synergistic effect of wire bending and salivary pH on surface properties and mechanical properties of orthodontic stainless steel archwires.

PubMed

Hobbelink, Marieke G; He, Yan; Xu, Jia; Xie, Huixu; Stoll, Richard; Ye, Qingsong

2015-01-01

The aim of this study was to investigate the corrosive behaviour of stainless steel archwires in a more clinically relevant way by bending and exposing to various pH. One hundred and twenty pieces of rectangular stainless steel wires (0.43 × 0.64 mm) were randomly assigned into four groups. In each group, there were 15 pieces of bent wires and 15 straight ones. Prior to measurements of the wires, as individual experimental groups (group 1, 2, and 3), the wires were exposed to artificial saliva for 4 weeks at pH 5.6, 6.6, and 7.6, respectively. A control group of wires (group 4) remained in air for the same period of time before sent for measurements. Surface roughness (Ra-value) was measured by a profilometer. Young's modulus and maximum force were determined by a four-point flexural test apparatus. Scanning electron microscopy was used to observe the surface morphology of straight wire. Differences between groups were examined using a two-way analysis of variance (ANOVA). Mean surface roughness values, flexural Young's moduli, and maximum force values of bent wires are significantly different from those of the straight wires, which was the main effect of wire bending, ignoring the influence of pH. A significant effect was found between Ra-values regarding the main effect of pH, ignoring the influence of shape. There was a significant interaction effect of bending and pH on flexural Young's moduli of stainless steel archwires, while pH did not show much impact on the maximum force values of those stainless steel wires. Bigger surface irregularities were seen on SEM images of straight wires immersed in artificial saliva at pH 5.6 compared to artificial saliva at other pH values. Surface depth (Rz) was more sensitive than Ra in revealing surface roughness, both measured from 3D reconstructed SEM images. Ra showed a comparable result of surface roughness to Ra-value measured by the profilometer. Bending has a significant influence on surface roughness and mechanical properties of rectangular SS archwires. pH plays a synergistic effect on the change of mechanical properties of stainless steel (SS) wires along with wire bending.

Reactive polymer coatings: A robust platform towards sophisticated surface engineering for biotechnology

NASA Astrophysics Data System (ADS)

Chen, Hsien-Yeh

Functionalized poly(p-xylylenes) or so-called reactive polymers can be synthesized via chemical vapor deposition (CVD) polymerization. The resulting ultra-thin coatings are pinhole-free and can be conformally deposited to a wide range of substrates and materials. More importantly, the equipped functional groups can served as anchoring sites for tailoring the surface properties, making these reactive coatings a robust platform that can deal with sophisticated challenges faced in biointerfaces. In this work presented herein, surface coatings presenting various functional groups were prepared by CVD process. Such surfaces include aldehyde-functionalized coating to precisely immobilize saccharide molecules onto well-defined areas and alkyne-functionalized coating to click azide-modified molecules via Huisgen 1,3-dipolar cycloaddition reaction. Moreover, CVD copolymerization has been conducted to prepare multifunctional coatings and their specific functions were demonstrated by the immobilization of biotin and NHS-ester molecules. By using a photodefinable coating, polyethylene oxides were immobilized onto a wide range of substrates through photo-immobilization. Spatially controlled protein resistant properties were characterized by selective adsorption of fibrinogen and bovine serum albumin as model systems. Alternatively, surface initiator coatings were used for polymer graftings of polyethylene glycol) methyl ether methacrylate, and the resultant protein- and cell- resistant properties were characterized by adsorption of kinesin motor proteins, fibrinogen, and murine fibroblasts (NIH3T3). Accessibility of reactive coatings within confined microgeometries was systematically studied, and the preparation of homogeneous polymer thin films within the inner surface of microchannels was demonstrated. Moreover, these advanced coatings were applied to develop a dry adhesion process for microfluidic devices. This process provides (i) excellent bonding strength, (ii) extended storage time prior to bonding, and (iii) well-defined surface functionalities for subsequent surface modifications. Finally, we have also prepared surface microstructures and surface patterns using reactive coatings via photopatterning, projection lithography, supramolecular nanostamping (SuNS), and vapor-assisted micropatterning in replica structures (VAMPIR). These patterning techniques can be complimentarily used and provide access to precisely confined microenvironments on flat and curved geometries. Reactive coatings provide a technology platform that creates active, long-term control and may lead to improved mimicry of biological systems for effective bio-functional modifications.

High-rate production of micro- and nanostructured surfaces: Injection molding and novel process for metal tooling manufacturing

NASA Astrophysics Data System (ADS)

De Jesus Vega, Marisely

Devices containing micro and nanostructured surfaces are developing and constantly finding new applications, especially for medical diagnostics, point-of-care applications, and microneedles. They are also employed in the functionalization of surfaces for superhydrophobicity, drag reduction, or reversible adhesion by mimicking bio-inspired surfaces. This research provides a thorough investigation on the effects of different polymeric materials and processing conditions on the replication of micro and nanostructured surfaces via injection molding. In addition, this dissertation also presents a novel approach for the production of durable microstructured metal tooling to be used for the production of surfaces with microchannels via injection molding. Materials such as thermoplastic vulcanizates are substituting regular thermoplastic materials and vulcanized elastomers in many applications due to their outstanding properties and ease of processability. These material properties broaden the scope of applications for microstructured surfaces. However, there is a need for understanding how these materials behave in microinjection molding since thermoplastic elastomers' behavior during injection molding have been shown to differ from that of the widely understood behavior of thermoplastics. Replication of microstructured surfaces using thermoplastic vulcanizates (TPV) was studied in the first part of this thesis. TPVs with different hardness's were molded using microinjection molding with various processing conditions and the replication and surface details of 20 microm pillars (aspect ratio of 1:1) were characterized. In the second part of this research liquid silicone rubber (LSR) was studied as a material for the production of micro and nanostructured surfaces. LSR is a silicone based material such as polydimethylsiloxane (PDMS), which is widely used for research and development of micro and nanostructured devices, and thus provides all the benefits of PDMS but can be rapidly processed via liquid injection molding. LSR with its excellent mechanical properties, transparency, non-toxicity and rapid molding capabilities can bring the production of micro and nanostructured surfaces from laboratory research facilities to high-rate manufacturing. However, previous research on microstructured surfaces made off LSR does not focus on the processing aspect of this material. Therefore, there is a lack of understanding of how different processing conditions affect the replication of microstructures. Additionally, there are no reports molding nanostructures of LSR. Features between 115 microm and 0.250 microm were molded in this work and the effect of different processing conditions and features sizes were studied. For the last part of this work, a novel metal additive manufacturing technique was used for the production of microstructured surfaces to be used as tooling for injection molding. The printing method consists of metal pastes printed through a tip onto a steel substrate. Prior work has shown spreading and swelling of features when metal pastes extrude out of the printing tip. PDMS was studied as a binder material to minimize spreading and swelling of the features by curing right after printing. In addition, prior work has shown durability of this metal printed tool up to 5000 injection molding cycles. This work compares this durability to durability of commercially available selective laser sintering metal tools. Furthermore, surface roughness was studied as this is one of the most important things to consider when molding microchannels for certain applications.

Characterizing Volumetric Strain at Brady Hot Springs, Nevada, USA Using Geodetic Data, Numerical Models, and Prior Information

NASA Astrophysics Data System (ADS)

Reinisch, E. C.; Feigl, K. L.; Cardiff, M. A.; Morency, C.; Kreemer, C.; Akerley, J.

2017-12-01

Time-dependent deformation has been observed at Brady Hot Springs using data from the Global Positioning System (GPS) and interferometric synthetic aperture radar (InSAR) [e.g., Ali et al. 2016, http://dx.doi.org/10.1016/j.geothermics.2016.01.008]. We seek to determine the geophysical process governing the observed subsidence. As two end-member hypotheses, we consider thermal contraction and a decrease in pore fluid pressure. A decrease in temperature would cause contraction in the subsurface and subsidence at the surface. A decrease in pore fluid pressure would allow the volume of pores to shrink and also produce subsidence. To simulate these processes, we use a dislocation model that assumes uniform elastic properties in a half space [Okada, 1985]. The parameterization consists of many cubic volume elements (voxels), each of which contracts by closing its three mutually orthogonal bisecting square surfaces. Then we use linear inversion to solve for volumetric strain in each voxel given a measurement of range change. To differentiate between the two possible hypotheses, we use a Bayesian framework with geostatistical prior information. We perform inversion using each prior to decide if one leads to a more geophysically reasonable interpretation than the other. This work is part of a project entitled "Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology, Geodesy, and Hydrology" and is supported by the Geothermal Technology Office of the U.S. Department of Energy [DE-EE0006760].

7 CFR 1955.10 - Voluntary conveyance of real property by the borrower to the Government.

Code of Federal Regulations, 2010 CFR

2010-01-01

... whether or not prior liens will be paid. Normally, the Government will pay prior liens in full prior to... its successor agency under Public Law 103-354 liens) and pay real estate taxes or assessments which... Law 103-354 pays will be added to the debt; a credit equal to the market value of the property, as...

Glass transition behavior of polystyrene/silica nanocomposites.

NASA Astrophysics Data System (ADS)

Xie, Yuping; Sen, Sudeepto; Kumar, Sanat; Bansal, Amitabh

2006-03-01

The change in thermomechanical properties of nano-filled polymers is of considerable scientific and technological interest. The interaction between the nanofillers and the matrix polymer controls the nanocomposite properties. We will present the results from recent and ongoing DSC experiments on polystyrene/silica nanocomposites. Polystyrene of different molecular weights (and from different sources) and silica nanoparticles 10-15 nm in diameter (both as received from Nissan and surface modified by grafted or physisorbed polystyrene) are being used to process the nanocomposites. We are studying trends in the glass transition behavior by changing the matrix molecular weights and the silica weight fractions. Recent data indicate that the glass transition temperature can both decrease and increase depending on the polymer-nanofiller combination as well as the thermal treatment of the nanocomposites prior to the DSC runs.

Superfund Record of Decision (EPA Region 3): Metal Banks, Philadelphia, PA, December 31, 1997

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

NONE

1998-09-01

This Record of Decision (ROD) presents the final remedial action selected for the Metal Bank Superfund Site (Site), located in northeastern Philadelphia, Pennsylvania. The remedy addresses contaminated soil, sediment, surface water, and groundwater at the Site and includes: installation of an oil collection system consisting of a sheet pile wall around the southern and western perimeter of the property; installation of temporary cofferdams prior to soil/sediment excavation to minimize transport of contamination into the Delaware River; excavation of contaminated soil within the Courtyard Area within two feet of the surface where polychlorinated biphenyl (PCB) concentrations exceed 10 ppm; disposal ofmore » contaminated soils and sediments that are hazardous; removal and disposal of the underground storage tank and its contents from the Southern Portion of the property; backfilling of excavated areas; posting signs prohibiting consumption of fish caught in the Delaware River in the vicinity of the Site; restrictions on the deed to the property to prevent future residential or agricultural use of the Site, use of the groundwater, and intrusive activities into the subsurface soils below the water table in the Southern Portion of the property; additional investigation to determine whether dense non-aqueous phase liquids (DNAPLs) are present at the Site and whether the storm sewer system in the vicinity of the Site is contaminated; and monitoring of groundwater, the Delaware River, and the Baxter Water intake.« less

Cold Gas-Sprayed Deposition of Metallic Coatings onto Ceramic Substrates Using Laser Surface Texturing Pre-treatment

NASA Astrophysics Data System (ADS)

Kromer, R.; Danlos, Y.; Costil, S.

2018-04-01

Cold spraying enables a variety of metals dense coatings onto metal surfaces. Supersonic gas jet accelerates particles which undergo with the substrate plastic deformation. Different bonding mechanisms can be created depending on the materials. The particle-substrate contact time, contact temperature and contact area upon impact are the parameters influencing physicochemical and mechanical bonds. The resultant bonding arose from plastic deformation of the particle and substrate and temperature increasing at the interface. The objective was to create specific topography to enable metallic particle adhesion onto ceramic substrates. Ceramic did not demonstrate deformation during the impact which minimized the intimate bonds. Laser surface texturing was hence used as prior surface treatment to create specific topography and to enable mechanical anchoring. Particle compressive states were necessary to build up coating. The coating deposition efficiency and adhesion strength were evaluated. Textured surface is required to obtain strong adhesion of metallic coatings onto ceramic substrates. Consequently, cold spray coating parameters depend on the target material and a methodology was established with particle parameters (diameters, velocities, temperatures) and particle/substrate properties to adapt the surface topography. Laser surface texturing is a promising tool to increase the cold spraying applications.

Cleaning of copper traces on circuit boards with excimer laser radiation

NASA Astrophysics Data System (ADS)

Wesner, D. A.; Mertin, M.; Lupp, F.; Kreutz, E. W.

1996-04-01

Cleaning of Cu traces on circuit boards is studied using pulsed excimer laser radiation (pulse width ˜ 20 ns, wavelength 248 nm), with the goal of improving the properties of the Cu surface for soldering and bonding. Traces with well-defined oxide overlayers are cleaned by irradiation in air using ≤ 10 3 laser pulses at fluences per pulse of ≤ 2 J cm -2. After treatment the surface morphology is analyzed using optical microscopy, optical profilometry, and scanning electron microscopy, while the chemical state of the surface is investigated with X-ray photoelectron (XPS) spectroscopy. Ellipsometry is used to determine the oxide overlayer thickness. Prior to cleaning samples exhibit a contamination overlayer about 15-25 nm in thickness containing Cu 2O and C. Cleaning reduces the overlayer thickness to ≤ 10 nm by material removal. The process tends to be self-limiting, since the optical reflectivity of the oxidized Cu surface for laser radiation is smaller than that of the cleaned surface. Additionally, the interaction with the laser radiation results in surface segregation of a minor alloy component out of the bulk (e.g. Zn), which may help to passivate the surface for further chemical reactions.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, J.D.

1993-11-09

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of standard polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

A review on remotely sensed land surface temperature anomaly as an earthquake precursor

NASA Astrophysics Data System (ADS)

Bhardwaj, Anshuman; Singh, Shaktiman; Sam, Lydia; Joshi, P. K.; Bhardwaj, Akanksha; Martín-Torres, F. Javier; Kumar, Rajesh

2017-12-01

The low predictability of earthquakes and the high uncertainty associated with their forecasts make earthquakes one of the worst natural calamities, capable of causing instant loss of life and property. Here, we discuss the studies reporting the observed anomalies in the satellite-derived Land Surface Temperature (LST) before an earthquake. We compile the conclusions of these studies and evaluate the use of remotely sensed LST anomalies as precursors of earthquakes. The arrival times and the amplitudes of the anomalies vary widely, thus making it difficult to consider them as universal markers to issue earthquake warnings. Based on the randomness in the observations of these precursors, we support employing a global-scale monitoring system to detect statistically robust anomalous geophysical signals prior to earthquakes before considering them as definite precursors.

Preparation of glucose sensors using gold nanoparticles modified diamond electrode

NASA Astrophysics Data System (ADS)

Fachrurrazie; Ivandini, T. A.; Wibowo, W.

2017-04-01

A glucose sensor was successfully developed by immobilizing glucose oxidase (GOx) at boron-doped diamond (BDD) electrodes. Prior to GOx immobilization, the BDD was modified with gold nanoparticles (AuNPs). To immobilize AuNPs, the gold surface was modified to nitrogen termination. The characterization of the electrode surface was performed using an X-ray photoelectron spectroscopy and a scanning electron microscope, while the electrochemical properties of the enzyme electrode were characterized using cyclic voltammetry. Cyclic voltammograms of the prepared electrode for D-glucose in phosphate buffer solution pH 7 showed a new reduction peak at +0.16 V. The currents of the peak were linear in the concentration range of 0.1 M to 0.9 M, indicated that the GOx-AuNP-BDD can be applied for electrochemical glucose detection.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, J.D.

1995-03-07

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of ``standard`` polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, John D.

1993-01-01

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of "standard" polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Vacuum deposition and curing of liquid monomers apparatus

DOEpatents

Affinito, John D.

1996-01-01

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of "standard" polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, John D.

1995-01-01

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of "standard" polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Quantitative analysis of visible surface defect risk in tablets during film coating using terahertz pulsed imaging.

PubMed

Niwa, Masahiro; Hiraishi, Yasuhiro

2014-01-30

Tablets are the most common form of solid oral dosage produced by pharmaceutical industries. There are several challenges to successful and consistent tablet manufacturing. One well-known quality issue is visible surface defects, which generally occur due to insufficient physical strength, causing breakage or abrasion during processing, packaging, or shipping. Techniques that allow quantitative evaluation of surface strength and the risk of surface defect would greatly aid in quality control. Here terahertz pulsed imaging (TPI) was employed to evaluate the surface properties of core tablets with visible surface defects of varying severity after film coating. Other analytical methods, such as tensile strength measurements, friability testing, and scanning electron microscopy (SEM), were used to validate TPI results. Tensile strength and friability provided no information on visible surface defect risk, whereas the TPI-derived unique parameter terahertz electric field peak strength (TEFPS) provided spatial distribution of surface density/roughness information on core tablets, which helped in estimating tablet abrasion risk prior to film coating and predicting the location of the defects. TPI also revealed the relationship between surface strength and blending condition and is a nondestructive, quantitative approach to aid formulation development and quality control that can reduce visible surface defect risk in tablets. Copyright © 2013 Elsevier B.V. All rights reserved.

A novel method for improving cerussite sulfidization

NASA Astrophysics Data System (ADS)

Feng, Qi-cheng; Wen, Shu-ming; Zhao, Wen-juan; Cao, Qin-bo; Lü, Chao

2016-06-01

Evaluation of flotation behavior, solution measurements, and surface analyses were performed to investigate the effects of chloride ion addition on the sulfidization of cerussite in this study. Micro-flotation tests indicate that the addition of chloride ions prior to sulfidization can significantly increase the flotation recovery of cerussite, which is attributed to the formation of more lead sulfide species on the mineral surface. Solution measurement results suggest that the addition of chloride ions prior to sulfidization induces the transformation of more sulfide ions from pulp solution onto the mineral surface by the formation of more lead sulfide species. X-ray diffraction and energy-dispersive spectroscopy indicate that more lead sulfide species form on the mineral surface when chloride ions are added prior to sulfidization. These results demonstrate that the addition of chloride ions prior to sulfidization can significantly improve the sulfidization of cerussite, thereby enhancing the flotation performance.

Engineering the Mechanical Properties of Ultrabarrier Films Grown by Atomic Layer Deposition for the Encapsulation of Printed Electronics

DOE PAGES

Bulusu, Anuradha; Singh, Ankit K.; Wang, Cheng-Yin; ...

2015-08-28

Direct deposition of barrier films by atomic layer deposition (ALD) onto printed electronics presents a promising method for packaging devices. Films made by ALD have been shown to possess desired ultrabarrier properties, but face challenges when directly grown onto surfaces with varying composition and topography. Challenges include differing nucleation and growth rates across the surface, stress concentrations from topography and coefficient of thermal expansion (CTE) mismatch, elastic mismatch, and particle contamination that may impact the performance of the ALD barrier. In such cases, a polymer smoothing layer may be needed to coat the surface prior to ALD barrier film deposition.more » We present the impact of architecture on the performance of aluminum oxide (Al2O3)/hafnium oxide (HfO2) ALD nanolaminate barrier films deposited on fluorinated polymer layer using an optical calcium (Ca) test under damp heat. It is found that with increasing polymer thickness, the barrier films with residual tensile stress are prone to cracking resulting in rapid failure of the Ca sensor at 50{degree sign}C/85% RH. Inserting a SiNx layer with residual compressive stress between the polymer and ALD layers is found to prevent cracking over a range of polymer thicknesses with more than 95% of the Ca sensor remaining after 500 h of testing. These results suggest that controlling mechanical properties and film architecture play an important role in the performance of direct deposited ALD barriers.« less

Pulsed Electrodeposition of Ni with Uniform Co-Deposition of Micron Sized Diamond Particles on Copper Substrate

NASA Astrophysics Data System (ADS)

Kumar, Prashant; Mahato, Neelima

Nanocrystalline nickel was deposited on annealed copper substrate of unit surface area (1 cm2) via pulsed electrodeposition technique using potentiostat (model 263A, Princeton Applied Research, USA) from Watts bath containing nickel sulfate, nickel chloride ,boric acid and sodium citrate. Diamond particles of three different dimensions, viz., 1, 3, and 6 micron were added separately (5 g/L) to the watts bath and co-deposited along with nanocrystalline nickel. The temperature was kept constant at 55 °C. The solution was ultrasonicated for 45-60 minutes prior to deposition to disperse the diamond particles uniformly in the bath. Depositions were carried out at different current densities, viz., 50, 100,150 and 200 mA/ cm2 for different durations, i.e.7, 14 and 21 minutes and best results are optimized for 200mA/cm2 so it is used for all process here .Scanning electron micrographs (SEM) show uniform deposition of microstructure of micron diamond on the surface of copper embedded in the nickel matrix. Elemental mapping confirmed uniform deposition of nickel and diamond with almost no cracks or pits. Mechanical properties of the sample such as, Vicker's hardness increased abruptly after the electrodeposition. Improved microstructural and mechanical properties were found in the case of electrodeposited surfaces containing followed by 3 and 6 micron diamond. The properties were also found better than those processed via stirring the solution during deposition.

Thermomechanical and chemical properties of porous W/liquid Li hybrid systems as plasma-facing self-healing surfaces

NASA Astrophysics Data System (ADS)

Kapat, Aveek; Lang, Eric; Neff, Anton; Allain, Jean Paul

2017-10-01

The environmental conditions at the plasma-material interface of a future nuclear fusion reactor interacting will be extreme. The incident plasma will carry heat fluxes of the order of 100's of MWm-2 and particle fluxes that can average 1024 m-2s-1. The fusion reactor wall would need to operate at high temperatures near 800 C and the incident energy of particles will vary from a few eV ions to MeV neutrons. A hybrid system, inspired by self-healing solid-state concepts, combines the ductile phase of liquid Li within a solid phase porous W. The liquid Li serves to control hydrogen retention and provide vapor shielding, within the framework of a tunable porosity to optimize edge plasma conditions [2]. Additionally, the porous interface can also provide for effective defect sinks for high duty cycle neutron damage. The surface chemistry of liquid Li on a porous surface varied with D irradiation is studied and its effect on retention. Prior results with refractory alloys have demonstrated effective wetting properties [3]. These hybrid systems, as well as traditional W samples, are bombarded with 500eV D2+and Ar+ at 230oC and 300oC. The Li, O, and C XPS peaks were examined and compared to controls. Additionally, the porous W is characterized for thermo-mechanical properties. Work supported by USDOE Contract DE- DE-SC0014267.

Critical evaluation and comparison of enrichment efficiency of multi-walled carbon nanotubes, C18 silica and activated carbon towards some pesticides from environmental waters.

PubMed

El-Sheikh, Amjad H; Sweileh, Jamal A; Al-Degs, Yahya S; Insisi, Ahmad A; Al-Rabady, Nancy

2008-02-15

In this work, optimization of multi-residue solid phase extraction (SPE) procedures coupled with high-performance liquid chromatography for the determination of Propoxur, Atrazine and Methidathion from environmental waters is reported. Three different sorbents were used in this work: multi-walled carbon nanotubes (MWCNTs), C18 silica and activated carbon (AC). The three optimized SPE procedures were compared in terms of analytical performance, application to environmental waters, cartridge re-use, adsorption capacity and cost of adsorbent. Although the adsorption capacity of MWCNT was larger than AC and C18, however, the analytical performance of AC could be made close to the other sorbents by appropriate optimization of the SPE procedures. A sample of AC was then oxidized with various oxidizing agents to show that ACs of various surface properties has different enrichment efficiencies. Thus researchers are advised to try AC of various surface properties in SPE of pollutants prior to using expensive sorbents (such as MWCNT and C18 silica).

Effect of degassing temperature on specific surface area and pore volume measurements of biochar

NASA Astrophysics Data System (ADS)

Sigmund, Gabriel; Hüffer, Thorsten; Kah, Melanie; Hofmann, Thilo

2017-04-01

Specific surface area, pore volume, and pore size distribution are key biochar properties that have been related to water and nutrient cycling, microbial activity as well as sorption potential for organic compounds. Specific surface area and pore volume are commonly determined by measurement of physisorption of N2 and/or CO2. The measurement requires prior degassing of the samples, which may change the structure of the materials. Information on degassing temperature is rarely reported in literature, and recommendations differ considerably between existing guidelines for biochar characterization. Therefore, the influence of degassing temperature on N2 and CO2physisorption measurements was investigated by systematically degassing a range of materials, including four biochars, Al2O3 and carbon nanotubes at different temperatures (105 ˚ C, 150 ˚ C, 200 ˚ C, 250 ˚ C and 300 ˚ C for ≥ 14 h each). Measured specific surface area and pore volume increased with increasing degassing temperature for all biochars. Additional surface area and pore volume may have become available as components in biochars volatilized during the degassing phase. The results of our study showed that (i) degassing conditions change material properties, and influence physisorption measurements for biochar (ii) comparison between parameters derived from different degassing protocols may not be appropriate, and (iii) degassing protocols should be harmonized in the biochar community [1]. [1] Sigmund, et al. (2016), "Biochar total surface area and total pore volume determined by N2 and CO2 physisorption are strongly influenced by degassing temperature", STOTEN, doi: http://dx.doi.org/10.1016/j.scitotenv.2016.12.023.

Corona plasma modification of polyamide 66 for the design of textile delivery systems for cosmetic therapy

NASA Astrophysics Data System (ADS)

Labay, C.; Canal, J. M.; Navarro, A.; Canal, C.

2014-10-01

Cosmetic and medical applications of technical textiles are a research expanding field. One of the added values of these new materials would be that they are suitable to contain and release active ingredients in a controlled manner. The influence of the initial state of the surface of polyamide 6.6 (PA66) fibers on the wetting properties of the fibers as well as on the incorporation of caffeine on the fibers and on its release kinetics from the fibers has been investigated. Comparison between industrially-finished PA66 fabrics and laboratory washed fabrics has been done to carry out this study. Furthermore, surface modification of the PA66 fibers by low temperature plasma has been studied regarding the modification of the physical, chemical and topographical properties of the textile fibers. Corona plasma treatment has been investigated to achieve surface modification in the first nanometers of polymer fibers surface in order to modulate the incorporation and the release of caffeine. It has been demonstrated that both initial state of the PA66 surface and prior plasma treatment of the PA66 fibers before the active principle incorporation condition caffeine release kinetics from the textile fibers. The final release percentage increases linearly with the C-O and Cdbnd O functional groups incorporated by plasma on the surface. It has also been established that the release amounts of caffeine achieved after 8 h from the PA66 fabric are in the same order of magnitude than topical doses of commercial gel-based formulations.

Processing, structure, property and performance relationships for the thermal spray of the internal surface of aluminum cylinders

NASA Astrophysics Data System (ADS)

Cook, David James

The increased need for automotive weight reduction has necessitated the use of aluminum for engine blocks. Conventional aluminum alloys cannot survive the constant wear from a piston ring reciprocating on the surface. However, a wear resistant thermal spray coating can be applied on the internal surface of the cylinder bore, which has significant advantages over other available options. Thermal spray is a well-established process for depositing molten, semi-molten, or solid particles onto a substrate to form a protective coating. For this application, the two main challenges were obtaining good wear resistance, and achieving good adhesion. To design a system capable of producing a well-adhered, wear resistant coating for this high volume application it is necessary to identify the overall processing, structure, properties, and performance relationships. The results will demonstrate that very important relationships exist among particle characteristics, substrate conditions, and the properties of the final coating. However, it is the scientific studies to understand some of the process physics in these relationships that allow recognition of the critical processing conditions that need to be controlled to ensure a consistent, reliable thermal spray coating. In this investigation, it will be shown that the critical microstructural aspect of the coating that produced the required tribological properties was the presence of wuestite (FeO). It was found that by using a low carbon steel material with compressed air atomizing gas, it was possible to create an Fe/FeO structure that exhibited excellent tribological properties. This study will also show that traditional thermal spray surface preparation techniques were not ideal for this application, therefore a novel alternative approach was developed. The application of a flux to the aluminum surface prior to thermal spray promotes excellent bond strengths to non-roughened aluminum. Analysis will show that this flux strips the oxide from the aluminum and allows for chemical bonding of the NiAl coating to the aluminum via the formation of intermetallics. By developing processing, structure, property, and performance relationships for the full process, it was possible to design a complete coating process to succeed in this application. The determination of these relationships and the underlying process physics improves reliability and instills confidence in the process.

Effects of different sterilization methods on the physico-chemical and bioresponsive properties of plasma-treated polycaprolactone films.

PubMed

Ghobeira, Rouba; Philips, Charlot; Declercq, Heidi; Cools, Pieter; De Geyter, Nathalie; Cornelissen, Ria; Morent, Rino

2017-01-24

For most tissue engineering applications, surface modification and sterilization of polymers are critical aspects determining the implant success. The first part of this study is thus dedicated to modifying polycaprolactone (PCL) surfaces via plasma treatment using a medium pressure dielectric barrier discharge, while the second part focuses on the sterilization of plasma-modified PCL. Chemical and physical surface changes are examined making use of water contact angle goniometry (WCA), x-ray photoelectron spectroscopy and atomic force microscopy. Bioresponsive properties are evaluated by performing cell culture tests. The results show that air and argon plasmas decrease the WCA significantly due to the incorporation of oxygen-containing functionalities onto the PCL surface, without modifying its morphology. Extended treatment times lead to PCL degradation, especially in the case of air plasma. In addition to surface modification, the plasma potential to sterilize PCL is studied with appropriate treatment times, but sterility has not been achieved so far. Therefore, plasma-modified films are subjected to UV, H 2 O 2 plasma (HP) and ethylene oxide (EtO) sterilizations. UV exposure of 3 h does not alter the PCL physico-chemical properties. A decreased wettability is observed after EtO sterilization, attributable to the modification of PCL chain ends reacting with EtO molecules. HP sterilization increases the WCA of the plasma-treated samples, presumably due to the scission of the hydrophilic bonds generated during the prior plasma treatments. Moreover, HP modifies the PCL surface morphology. For all the sterilizations, an improved cell adhesion and proliferation is observed on plasma-treated films compared to untreated ones. EtO shows the lowest proliferation rate compared to HP and UV. Overall, of the three sterilizations, UV is the most effective, since the physical alterations provoked by HP might interfere with the structural integrity when it comes to 3D scaffolds, and the chemical modifications caused by EtO, in addition to its toxicity, interfere with PCL bioactivity.

Irradiating of Bulk Soybeans: Influence on Their Functional and Sensory Properties for Soyfood Processing

NASA Technical Reports Server (NTRS)

Chia, Chiew-Ling; Wilson, Lester A.; Boylston, Terri; Perchonok, Michele; French, Stephen

2006-01-01

Soybeans were chosen for lunar and planetary missions, where soybeans will be supplied in bulk or grown locally, due to their nutritive value and ability to produce oil and protein for further food applications. However, soybeans must be processed into foods prior to consumption. Radiation that soybeans would be exposed to during bulk storage prior to and during a Mars mission may influence their germination and functional properties. The influence of radiation includes the affect of surface pasteurization to ensure the astronauts safety from food-borne illnesses (HACCP, CCP), and the affect of the amount of radiation the soybeans receive during a Mars mission. Decreases in the amount of natural antioxidants free radical formation, and oxidation-induced changes in the soybean will influence the nutritional value, texture, color, and aroma of soyfoods. The objective of this study was to determine the influence of pasteurization and sterilization surface radiation on whole soybeans using gamma and electron beam radiation. The influence of 0, 1, 5, 10, and 30kGy on microbial load, germination rate, ease of processing, and quality of soymilk and tofu were determined. Surface radiation of whole dry soybeans using electron beam or gamma rays from 1-30kGy did provide microbial safety for the astronauts. However, the lower dose levels had surviving yeasts and molds. These doses caused oxidative changes that resulted in soymilk and tofu with rancid aromas. GC-MS of the aroma compounds using SPME Headspace confirmed the presence of lipid oxidation compounds. Soybean germination ability was reduced as radiation dosage increased. While lower doses may reduce these problems, the ability to insure microbial safety of bulk soybeans will be lost. Counter measures could include vacuum packaging, nitrogen flushing, added antioxidants, and radiating under freezing conditions. Doses below 1kGy need to be investigated further to determine the influence of the radiation encountered during Mars missions.

Exogenous ROS-induced cell sheet transfer based on hematoporphyrin-polyketone film via a one-step process.

PubMed

Koo, Min-Ah; Lee, Mi Hee; Kwon, Byeong-Ju; Seon, Gyeung Mi; Kim, Min Sung; Kim, Dohyun; Nam, Ki Chang; Park, Jong-Chul

2018-04-01

To date, most of invasive cell sheet harvesting methods have used culture surface property variations, such as wettability, pH, electricity, and magnetism, to induce cell detachment. These methods that rely on surface property changes are effective when cell detachment prior to application is necessary, but of limited use when used for cell sheet transfer to target regions. The study reports a new reactive oxygen species (ROS)-induced strategy based on hematoporphyrin-incorporated polyketone film (Hp-PK film) to transfer cell sheets directly to target areas without an intermediate harvesting process. After green LED (510 nm) irradiation, production of exogenous ROS from the Hp-PK films induces cell sheet detachment and transfer. The study suggests that ROS-induced cell detachment property of the Hp-PK film is closely related to conformational changes of extracellular matrix (ECM) proteins. Also, this strategy with the Hp-PK film can be applied by regulating production rate of exogenous ROS in various types of cells, including fibroblasts, mesenchymal stem cells and keratinocytes. In conclusion, ROS-induced method using the Hp-PK film can be used for one-step cell sheet transplantation and has potential in biomedical applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Innate Immunity and Biomaterials at the Nexus: Friends or Foes

PubMed Central

Christo, Susan N.; Diener, Kerrilyn R.; Bachhuka, Akash; Vasilev, Krasimir; Hayball, John D.

2015-01-01

Biomaterial implants are an established part of medical practice, encompassing a broad range of devices that widely differ in function and structural composition. However, one common property amongst biomaterials is the induction of the foreign body response: an acute sterile inflammatory reaction which overlaps with tissue vascularisation and remodelling and ultimately fibrotic encapsulation of the biomaterial to prevent further interaction with host tissue. Severity and clinical manifestation of the biomaterial-induced foreign body response are different for each biomaterial, with cases of incompatibility often associated with loss of function. However, unravelling the mechanisms that progress to the formation of the fibrotic capsule highlights the tightly intertwined nature of immunological responses to a seemingly noncanonical “antigen.” In this review, we detail the pathways associated with the foreign body response and describe possible mechanisms of immune involvement that can be targeted. We also discuss methods of modulating the immune response by altering the physiochemical surface properties of the biomaterial prior to implantation. Developments in these areas are reliant on reproducible and effective animal models and may allow a “combined” immunomodulatory approach of adapting surface properties of biomaterials, as well as treating key immune pathways to ultimately reduce the negative consequences of biomaterial implantation. PMID:26247017

Quantification of cell response to polymeric composites using a two-dimensional gradient platform.

PubMed

Lin, Nancy J; Hu, Haiqing; Sung, Lipin; Lin-Gibson, Sheng

2009-07-01

A simple and straightforward screening process to assess the toxicity and corresponding cell response of dental composites would be useful prior to extensive in vitro or in vivo characterization. To this end, gradient composite samples were prepared with variations in filler content/type and in degree of conversion (DC). The DC was determined using near infrared spectroscopy (NIR), and the surface morphology was evaluated by laser scanning confocal microscopy (LSCM). RAW 264.7 macrophage-like cells were cultured directly on the composite gradient samples, and cell viability, density, and area were measured at 24 h. All three measures of cell response varied as a function of material properties. For instance, compositions with higher filler content had no reduction in cell viability or cell density, even at low conversions of 52%, whereas significant decreases in viability and density were present when the filler content was 35% or below (by mass). The overall results demonstrate the complexity of the cell-material interactions, with properties including DC, filler type, filler mass ratio, and surface morphology influencing the cell response. The combinatorial approach described herein enables simultaneous screening of multiple compositions and material properties, providing a more thorough characterization of cell response for the improved selection of biocompatible composite formulations and processing conditions.

Investigation of 'surface donors' in Al2O3/AlGaN/GaN metal-oxide-semiconductor heterostructures: Correlation of electrical, structural, and chemical properties

NASA Astrophysics Data System (ADS)

Ťapajna, M.; Stoklas, R.; Gregušová, D.; Gucmann, F.; Hušeková, K.; Haščík, Š.; Fröhlich, K.; Tóth, L.; Pécz, B.; Brunner, F.; Kuzmík, J.

2017-12-01

III-N surface polarization compensating charge referred here to as 'surface donors' (SD) was analyzed in Al2O3/AlGaN/GaN metal-oxide-semiconductor (MOS) heterojunctions using scaled oxide films grown by metal-organic chemical vapor deposition at 600 °C. We systematically investigated impact of HCl pre-treatment prior to oxide deposition and post-deposition annealing (PDA) at 700 °C. SD density was reduced down to 1.9 × 1013 cm-2 by skipping HCl pre-treatment step as compared to 3.3 × 1013 cm-2 for structures with HCl pre-treatment followed by PDA. The nature and origin of SD was then analyzed based on the correlation between electrical, micro-structural, and chemical properties of the Al2O3/GaN interfaces with different SD density (NSD). From the comparison between distributions of interface traps of MOS heterojunction with different NSD, it is demonstrated that SD cannot be attributed to interface trapped charge. Instead, variation in the integrity of the GaOx interlayer confirmed by X-ray photoelectron spectroscopy is well correlated with NSD, indicating SD may be formed by border traps at the Al2O3/GaOx interface.

Structural, Physical, and Compositional Analysis of Lunar Simulants and Regolith

NASA Technical Reports Server (NTRS)

Greenberg, Paul; Street, Kenneth W.; Gaier, James

2008-01-01

Relative to the prior manned Apollo and unmanned robotic missions, planned Lunar initiatives are comparatively complex and longer in duration. Individual crew rotations are envisioned to span several months, and various surface systems must function in the Lunar environment for periods of years. As a consequence, an increased understanding of the surface environment is required to engineer and test the associated materials, components, and systems necessary to sustain human habitation and surface operations. The effort described here concerns the analysis of existing simulant materials, with application to Lunar return samples. The interplay between these analyses fulfills the objective of ascertaining the critical properties of regolith itself, and the parallel objective of developing suitable stimulant materials for a variety of engineering applications. Presented here are measurements of the basic physical attributes, i.e. particle size distributions and general shape factors. Also discussed are structural and chemical properties, as determined through a variety of techniques, such as optical microscopy, SEM and TEM microscopy, Mossbauer Spectroscopy, X-ray diffraction, Raman microspectroscopy, inductively coupled argon plasma emission spectroscopy and energy dispersive X-ray fluorescence mapping. A comparative description of currently available stimulant materials is discussed, with implications for more detailed analyses, as well as the requirements for continued refinement of methods for simulant production.

Colour computer-generated holography for point clouds utilizing the Phong illumination model.

PubMed

Symeonidou, Athanasia; Blinder, David; Schelkens, Peter

2018-04-16

A technique integrating the bidirectional reflectance distribution function (BRDF) is proposed to generate realistic high-quality colour computer-generated holograms (CGHs). We build on prior work, namely a fast computer-generated holography method for point clouds that handles occlusions. We extend the method by integrating the Phong illumination model so that the properties of the objects' surfaces are taken into account to achieve natural light phenomena such as reflections and shadows. Our experiments show that rendering holograms with the proposed algorithm provides realistic looking objects without any noteworthy increase to the computational cost.

Self-assembly of fatty acids on hydroxylated Al surface and effects of their stability on wettability and nanoscale organization.

PubMed

Liascukiene, Irma; Steffenhagen, Marie; Asadauskas, Svajus J; Lambert, Jean-François; Landoulsi, Jessem

2014-05-27

The self-assembly of fatty acids (FA) on the surfaces of inorganic materials is a relevant way to control their wetting properties. While the mechanism of adsorption on model flat substrate is well described in the literature, interfacial processes remain poorly documented on nanostructured surfaces. In this study, we report the self-assembly of a variety of FA on a hydroxylated Al surface which exhibits a random nanoscale organization. Our results revealed a peculiar fingerprint due to the FA self-assembly which consists in the formation of aligned nanopatterns in a state of hierarchical nanostructuration, regardless of the molecular structure of the FA (chain length, level of unsaturation). After a significant removal of adsorbed FA using UV/O3 treatment, a complete wetting was reached, and a noticeable disturbance of the surface morphology was observed, evidencing the pivotal role of FA molecules to maintain these nanostructures. The origin of wetting properties was investigated prior to and after conditioning of FA-modified samples taking into account key parameters, namely the surface roughness and its composition. For this purpose, the Wenzel roughness, defined as the third moment of power spectral density, was used, as it is sensitive to high spatial frequency and thus to the obtained hierarchical level of nanostructuration. Our results revealed that no correlation can be made between water contact angles (θ(w)) and the Wenzel roughness. By contrast, θ(w) strongly increased with the amount of -CHx- groups exhibited by adsorbed FA. These findings suggest that the main origin of hydrophobization is the presence of self-assembled molecules and that the surface roughness has only a small contribution to the wettability.

The Power Prior: Theory and Applications

PubMed Central

Ibrahim, Joseph G.; Chen, Ming-Hui; Gwon, Yeongjin; Chen, Fang

2015-01-01

The power prior has been widely used in many applications covering a large number of disciplines. The power prior is intended to be an informative prior constructed from historical data. It has been used in clinical trials, genetics, health care, psychology, environmental health, engineering, economics, and business. It has also been applied for a wide variety of models and settings, both in the experimental design and analysis contexts. In this review article, we give an A to Z exposition of the power prior and its applications to date. We review its theoretical properties, variations in its formulation, statistical contexts for which it has been used, applications, and its advantages over other informative priors. We review models for which it has been used, including generalized linear models, survival models, and random effects models. Statistical areas where the power prior has been used include model selection, experimental design, hierarchical modeling, and conjugate priors. Prequentist properties of power priors in posterior inference are established and a simulation study is conducted to further examine the empirical performance of the posterior estimates with power priors. Real data analyses are given illustrating the power prior as well as the use of the power prior in the Bayesian design of clinical trials. PMID:26346180

Shape-driven 3D segmentation using spherical wavelets.

PubMed

Nain, Delphine; Haker, Steven; Bobick, Aaron; Tannenbaum, Allen

2006-01-01

This paper presents a novel active surface segmentation algorithm using a multiscale shape representation and prior. We define a parametric model of a surface using spherical wavelet functions and learn a prior probability distribution over the wavelet coefficients to model shape variations at different scales and spatial locations in a training set. Based on this representation, we derive a parametric active surface evolution using the multiscale prior coefficients as parameters for our optimization procedure to naturally include the prior in the segmentation framework. Additionally, the optimization method can be applied in a coarse-to-fine manner. We apply our algorithm to the segmentation of brain caudate nucleus, of interest in the study of schizophrenia. Our validation shows our algorithm is computationally efficient and outperforms the Active Shape Model algorithm by capturing finer shape details.

How Much Can We Learn from a Single Chromatographic Experiment? A Bayesian Perspective.

PubMed

Wiczling, Paweł; Kaliszan, Roman

2016-01-05

In this work, we proposed and investigated a Bayesian inference procedure to find the desired chromatographic conditions based on known analyte properties (lipophilicity, pKa, and polar surface area) using one preliminary experiment. A previously developed nonlinear mixed effect model was used to specify the prior information about a new analyte with known physicochemical properties. Further, the prior (no preliminary data) and posterior predictive distribution (prior + one experiment) were determined sequentially to search towards the desired separation. The following isocratic high-performance reversed-phase liquid chromatographic conditions were sought: (1) retention time of a single analyte within the range of 4-6 min and (2) baseline separation of two analytes with retention times within the range of 4-10 min. The empirical posterior Bayesian distribution of parameters was estimated using the "slice sampling" Markov Chain Monte Carlo (MCMC) algorithm implemented in Matlab. The simulations with artificial analytes and experimental data of ketoprofen and papaverine were used to test the proposed methodology. The simulation experiment showed that for a single and two randomly selected analytes, there is 97% and 74% probability of obtaining a successful chromatogram using none or one preliminary experiment. The desired separation for ketoprofen and papaverine was established based on a single experiment. It was confirmed that the search for a desired separation rarely requires a large number of chromatographic analyses at least for a simple optimization problem. The proposed Bayesian-based optimization scheme is a powerful method of finding a desired chromatographic separation based on a small number of preliminary experiments.

Vacuum deposition and curing of liquid monomers apparatus

DOEpatents

Affinito, J.D.

1996-08-20

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of ``standard`` polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface. 3 figs.

A Technique for Transient Thermal Testing of Thick Structures

NASA Technical Reports Server (NTRS)

Horn, Thomas J.; Richards, W. Lance; Gong, Leslie

1997-01-01

A new open-loop heat flux control technique has been developed to conduct transient thermal testing of thick, thermally-conductive aerospace structures. This technique uses calibration of the radiant heater system power level as a function of heat flux, predicted aerodynamic heat flux, and the properties of an instrumented test article. An iterative process was used to generate open-loop heater power profiles prior to each transient thermal test. Differences between the measured and predicted surface temperatures were used to refine the heater power level command profiles through the iteration process. This iteration process has reduced the effects of environmental and test system design factors, which are normally compensated for by closed-loop temperature control, to acceptable levels. The final revised heater power profiles resulted in measured temperature time histories which deviated less than 25 F from the predicted surface temperatures.

Carboxyl functionalization of carbon fibers via aryl diazonium reaction in molten urea to enhance interfacial shear strength

NASA Astrophysics Data System (ADS)

Wang, Yuwei; Meng, Linghui; Fan, Liquan; Wu, Guangshun; Ma, Lichun; Zhao, Min; Huang, Yudong

2016-01-01

Using molten urea as the solvent, carbon fibers were functionalized with carboxylic acid groups via aryl diazonium reaction in 15 min to improve their interfacial bonding with epoxy resin. The surface functionalization was quantified by X-ray photoelectron spectroscopy, which showed that the relative surface coverage of carboxylic acid groups increased from an initial percentage of 3.17-10.41%. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 66%. Meanwhile, the technique did not adopt any pre-oxidation step to produce functional groups prior to grafting and was shown to maintain the tensile strength of the fibers. This methodology provided a rapid, facile and economically viable route to produce covalently functionalized carbon fibers in large quantities with an eco-friendly method.

The effect of hot isostatic pressing parameters on microstructure and mechanical properties of Eurofer powder HIPed material

NASA Astrophysics Data System (ADS)

Gentzbittel, J. M.; Chu, I.; Burlet, H.

2002-12-01

The production of reduced activation ferritic/martensitic (RAFM) steel by powder metallurgy and high isostatic pressing (HIP) offers numerous advantages for different nuclear applications. The objective of this work is to optimise the Eurofer powder HIP process in order to obtain RAFM solid HIPed steel with similar mechanical properties to those of a forged material. Starting from the forged solid Eurofer steel batch, the material is atomized and the Eurofer powder is characterized in terms of granulometry, chemical composition, surface oxides, etc. Different compaction HIP cycle parameters in the temperature range (950-1100 °C) are tested. The chemical composition of the HIPed material is comparable to the initial forged Eurofer. All the obtained materials are fully dense and the microstructure of the compacted material is well martensitic. The prior austenite grain size seems to be constant in this temperature range. The mechanical tests performed at room temperature reveal acceptable hardness, tensile and Charpy impact properties regarding the ITER specification.

Mechanical properties testing of candidate polymer matrix materials for use in high performance composites

NASA Technical Reports Server (NTRS)

Zimmerman, R. S.; Adams, D. F.

1985-01-01

The mechanical properties of four candidate neat resin systems for use in graphite/epoxy composites are characterized. This includes tensile and shear stiffnesses and strengths, coefficients of thermal and moisture expansion, and fracture toughness. Tests are conducted on specimens in the dry state and moisture-saturated, at temperatures of 23C, 82C and 121C. The neat resins tested are Hexcel HX-1504, Narmco 5245-C, American Cyanamid CYCOM 907, and Union Carbide ERX-4901A (MDA). Results are compared with those obtained for four other epoxy resins tested in a prior program, i.e., Hercules 3502, 2220-1, and 2220-3, and Ciba-Geigy Fibredux 914, as well as with available Hercules 3501-6 data. Scanning electron microscopic examination of fracture surfaces is performed to permit the correlation of observed failure modes with the environmental test conditions. A finite element micromechanics analysis is used to predict unidirectional composite response under various test conditions, using the measured neat resin properties as input data.

Direct metal brazing to cermet feedthroughs

DOEpatents

Not Available

1982-07-29

An improved method for brazing metallic components to a cermet surface in an alumina substrate eliminates the prior art metallized layer over the cermet via and adjoining alumina surfaces. Instead, a nickel layer is applied over the cermet surface only and metallic components are brazed directly to this nickel coated cermet surface. As a result, heretofore unachievable tensile strength joints are produced. In addition, cermet vias with their brazed metal components can be spaced more closely in the alumina substrate because of the elimination of the prior art metallized alumina surfaces.

Direct metal brazing to cermet feedthroughs

DOEpatents

Hopper, Jr., Albert C.

1984-12-18

An improved method for brazing metallic components to a cermet surface in an alumina substrate eliminates the prior art metallized layer over the cermet via and adjoining alumina surfaces. Instead, a nickel layer is applied over the cermet surface only and metallic components are brazed directly to this nickel coated cermet surface. As a result, heretofore unachievable tensile strength joints are produced. In addition, cermet vias with their brazed metal components can be spaced more closely in the alumina substrate because of the elimination of the prior art metallized alumina surfaces.

39 CFR 601.102 - Revocation of prior purchasing regulations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 39 Postal Service 1 2010-07-01 2010-07-01 false Revocation of prior purchasing regulations. 601.102 Section 601.102 Postal Service UNITED STATES POSTAL SERVICE PROCUREMENT SYSTEM FOR THE U.S. POSTAL SERVICE: INTELLECTUAL PROPERTY RIGHTS OTHER THAN PATENTS PURCHASING OF PROPERTY AND SERVICES § 601.102...

39 CFR 601.102 - Revocation of prior purchasing regulations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 39 Postal Service 1 2011-07-01 2011-07-01 false Revocation of prior purchasing regulations. 601.102 Section 601.102 Postal Service UNITED STATES POSTAL SERVICE PROCUREMENT SYSTEM FOR THE U.S. POSTAL SERVICE: INTELLECTUAL PROPERTY RIGHTS OTHER THAN PATENTS PURCHASING OF PROPERTY AND SERVICES § 601.102...

Modifying Matrix Materials to Increase Wetting and Adhesion

NASA Technical Reports Server (NTRS)

Zhong, Katie

2011-01-01

In an alternative approach to increasing the degrees of wetting and adhesion between the fiber and matrix components of organic-fiber/polymer matrix composite materials, the matrix resins are modified. Heretofore, it has been common practice to modify the fibers rather than the matrices: The fibers are modified by chemical and/or physical surface treatments prior to combining the fibers with matrix resins - an approach that entails considerable expense and usually results in degradation (typically, weakening) of fibers. The alternative approach of modifying the matrix resins does not entail degradation of fibers, and affords opportunities for improving the mechanical properties of the fiber composites. The alternative approach is more cost-effective, not only because it eliminates expensive fiber-surface treatments but also because it does not entail changes in procedures for manufacturing conventional composite-material structures. The alternative approach is best described by citing an example of its application to a composite of ultra-high-molecular- weight polyethylene (UHMWPE) fibers in an epoxy matrix. The epoxy matrix was modified to a chemically reactive, polarized epoxy nano-matrix to increase the degrees of wetting and adhesion between the fibers and the matrix. The modification was effected by incorporating a small proportion (0.3 weight percent) of reactive graphitic nanofibers produced from functionalized nanofibers into the epoxy matrix resin prior to combining the resin with the UHMWPE fibers. The resulting increase in fiber/matrix adhesion manifested itself in several test results, notably including an increase of 25 percent in the maximum fiber pullout force and an increase of 60-65 percent in fiber pullout energy. In addition, it was conjectured that the functionalized nanofibers became involved in the cross linking reaction of the epoxy resin, with resultant enhancement of the mechanical properties and lower viscosity of the matrix.

Lunar Dust and Lunar Simulant Activation, Monitoring, Solution and Cellular Toxicity Properties

NASA Technical Reports Server (NTRS)

Wallace, William; Jeevarajan, A. S.

2009-01-01

During the Apollo missions, many undesirable situations were encountered that must be mitigated prior to returning humans to the moon. Lunar dust (that part of the lunar regolith less than 20 microns in diameter) was found to produce several problems with mechanical equipment and could have conceivably produced harmful physiological effects for the astronauts. For instance, the abrasive nature of the dust was found to cause malfunctions of various joints and seals of the spacecraft and suits. Additionally, though efforts were made to exclude lunar dust from the cabin of the lunar module, a significant amount of material nonetheless found its way inside. With the loss of gravity correlated with ascent from the lunar surface, much of the finer fraction of this dust began to float and was inhaled by the astronauts. The short visits tothe Moon during Apollo lessened exposure to the dust, but the plan for future lunar stays of up to six months demands that methods be developed to minimize the risk of dust inhalation. The guidelines for what constitutes "safe" exposure will guide the development of engineering controls aimed at preventing the presence of dust in the lunar habitat. This work has shown the effects of grinding on the activation level of lunar dust, the changes in dissolution properties of lunar simulant, and the production of cytokines by cellular systems. Grinding of lunar dust leads to the production of radicals in solution and increased dissolution of lunar simulant in buffers of different pH. Additionally, ground lunar simulant has been shown to promote the production of IL-6 and IL-8, pro-inflammatory cytokines, by alveolar epithelial cells. These results provide evidence of the need for further studies on these materials prior to returning to the lunar surface.

Mechanical properties and cell-culture characteristics of a polycaprolactone kagome-structure scaffold fabricated by a precision extruding deposition system.

PubMed

Lee, Se-Hwan; Cho, Yong Sang; Hong, Myoung Wha; Lee, Bu-Kyu; Park, Yongdoo; Park, Sang-Hyug; Kim, Young Yul; Cho, Young-Sam

2017-09-13

To enhance the mechanical properties of three-dimensional (3D) scaffolds used for bone regeneration in tissue engineering, many researchers have studied their structure and chemistry. In the structural engineering field, the kagome structure has been known to have an excellent relative strength. In this study, to enhance the mechanical properties of a synthetic polymer scaffold used for tissue engineering, we applied the 3D kagome structure to a porous scaffold for bone regeneration. Prior to fabricating the biocompatible-polymer scaffold, the ideal kagome structure, which was manufactured by a 3D printer of the digital light processing type, was compared with a grid-structure, which was used as the control group, using a compressive experiment. A polycaprolactone (PCL) kagome-structure scaffold was successfully fabricated by additive manufacturing using a 3D printer with a precision extruding deposition head. To assess the physical characteristics of the fabricated PCL-kagome-structure scaffold, we analyzed its porosity, pore size, morphological structure, surface roughness, compressive stiffness, and mechanical bending properties. The results showed that, the mechanical properties of proposed kagome-structure scaffold were superior to those of a grid-structure scaffold. Moreover, Sarcoma osteogenic (Saos-2) cells were used to evaluate the characteristics of in vitro cell proliferation. We carried out cell counting kit-8 (CCK-8) and DNA contents assays. Consequently, the cell proliferation of the kagome-structure scaffold was increased; this could be because the surface roughness of the kagome-structure scaffold enhances initial cell attachment.

Temporal and vertical variability in optical properties of New England shelf waters during late summer and spring

NASA Astrophysics Data System (ADS)

Sosik, Heidi M.; Green, Rebecca E.; Pegau, W. Scott; Roesler, Collin S.

2001-05-01

Relationships between optical and physical properties were examined on the basis of intensive sampling at a site on the New England continental shelf during late summer 1996 and spring 1997. During both seasons, particles were found to be the primary source of temporal and vertical variability in optical properties since light absorption by dissolved material, though significant in magnitude, was relatively constant. Within the particle pool, changes in phytoplankton were responsible for much of the observed optical variability. Physical processes associated with characteristic seasonal patterns in stratification and mixing contributed to optical variability mostly through effects on phytoplankton. An exception to this generalization occurred during summer as the passage of a hurricane led to a breakdown in stratification and substantial resuspension of nonphytoplankton particulate material. Prior to the hurricane, conditions in summer were highly stratified with subsurface maxima in absorption and scattering coefficients. In spring, stratification was much weaker but increased over the sampling period, and a modest phytoplankton bloom caused surface layer maxima in absorption and scattering coefficients. These seasonal differences in the vertical distribution of inherent optical properties were evident in surface reflectance spectra, which were elevated and shifted toward blue wavelengths in the summer. Some seasonal differences in optical properties, including reflectance spectra, suggest that a significant shift toward a smaller particle size distribution occurred in summer. Shorter timescale optical variability was consistent with a variety of influences including episodic events such as the hurricane, physical processes associated with shelfbreak frontal dynamics, biological processes such as phytoplankton growth, and horizontal patchiness combined with water mass advection.

Comparison between diffuse infrared and acoustic transmission over the human skull.

PubMed

Wang, Q; Reganti, N; Yoshioka, Y; Howell, M; Clement, G T

2015-01-01

Skull-induced distortion and attenuation present a challenge to both transcranial imaging and therapy. Whereas therapeutic procedures have been successful in offsetting aberration using from prior CTs, this approach impractical for imaging. In effort to provide a simplified means for aberration correction, we have been investigating the use of diffuse infrared light as an indicator of acoustic properties. Infrared wavelengths were specifically selected for tissue penetration; however this preliminary study was performed through bone alone via a transmission mode to facilitate comparison with acoustic measurements. The inner surface of a half human skull, cut along the sagittal midline, was illuminated using an infrared heat lamp and images of the outer surface were acquired with an IR-sensitive camera. A range of source angles were acquired and averaged to eliminate source bias. Acoustic measurement were likewise obtained over the surface with a source (1MHz, 12.7mm-diam) oriented parallel to the skull surface and hydrophone receiver (1mm PVDF). Preliminary results reveal a positive correlation between sound speed and optical intensity, whereas poor correlation is observed between acoustic amplitude and optical intensity.

Effects of surface morphology of ZnO seed layers on growth of ZnO nanostructures prepared by hydrothermal method and annealing.

PubMed

Yim, Kwang Gug; Kim, Min Su; Leem, Jae-Young

2013-05-01

ZnO nanostructures were grown on Si (111) substrates by a hydrothermal method. Prior to growing the ZnO nanostructures, ZnO seed layers with different post-heat temperatures were prepared by a spin-coating process. Then, the ZnO nanostructures were annealed at 500 degrees C for 20 min under an Ar atmosphere. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) were carried out at room temperature (RT) to investigate the structural and optical properties of the as-grown and annealed ZnO nanostructures. The surface morphologies of the seed layers changed from a smooth surface to a mountain chain-like structure as the post-heating temperatures increased. The as-grown and annealed ZnO nanostructures exhibited a strong (002) diffraction peak. Compared to the as-grown ZnO nanostructures, the annealed ZnO nanostructures exhibited significantly strong enhancement in the PL intensity ratio by almost a factor of 2.

Hydrologic data at a wetland site, Millington, Shelby County, Tennessee, June 1993 through June 1994

USGS Publications Warehouse

Robinson, J.A.; Diehl, T.H.; Stogner, R.W.

1996-01-01

Hydrologic data at a wetland site near Millington, Shelby County, Tennessee, were collected from June 1993 through June 1994. The data were collected to support the efforts of the Tennessee Department of Transportation to better understand hydrologic properties at the site prior to wetland restoration. Water levels were monitored in thirteen 8-inch- diameter wells, approximately 2 feet deep. The casing in each well was slotted and screened from land surface to a depth of about 2 feet. Water-level recorders provided continuous records of stage during periods of wetland inundation, and depth to water table during periods of noninundation. A continuous-stage recorder was installed in a pond. Precipitation data were obtained from the Naval Air Station-Memphis, Millington, Tennessee. Land surface at the wells was inundated from 0 to 56 percent of the study period. Additionally, water levels in the wells were not more than 1.5 feet below land surface for 16 to 68 percent of the study period.

Altering Iron Oxide Nanoparticle Surface Properties Induce Cortical Neuron Cytotoxicity

PubMed Central

Rivet, Christopher J.; Yuan, Yuan; Borca-Tasciuc, Diana-Andra; Gilbert, Ryan J.

2014-01-01

Superparamagnetic iron oxide nanoparticles, with diameters in the range of a few tens of nanometers, display the ability to cross the blood-brain barrier and are envisioned as diagnostic and therapeutic tools in neuro-medicine. However, despite the numerous applications being explored, insufficient information is available on their potential toxic effect on neurons. While iron oxide has been shown to pose a decreased risk of toxicity, surface functionalization, often employed for targeted delivery, can significantly alter the biological response. This aspect is addressed in the present study, which investigates the response of primary cortical neurons to iron oxide nanoparticles with coatings frequently used in biomedical applications: aminosilane, dextran, and polydimethylamine. Prior to administering the particles to neuronal cultures, each particle type was thoroughly characterized to assess the (1) size of individual nanoparticles, (2) concentration of the particles in solution and (3) agglomeration size and morphology. Culture results show that polydimethylamine functionalized nanoparticles induce cell death at all concentrations tested by swift and complete removal of the plasma membrane. Aminosilane coated particles affected metabolic activity only at higher concentrations while leaving the membrane intact and dextran-coated nanoparticles partially altered viability at higher concentrations. These findings suggest that nanoparticle characterization and primary cell-based cytotoxicity evaluation should be completed prior to applying nanomaterials to the nervous system. PMID:22111864

Influence of amorphous content on compaction behaviour of anhydrous alpha-lactose.

PubMed

Ziffels, S; Steckel, H

2010-03-15

Modified lactoses are widely used as filler-binders in direct compression of tablets. Until today, little about the compaction behaviour of anhydrous alpha-lactose is known. In this study, a new method to prepare anhydrous alpha-lactose from alpha-lactose monohydrate by desiccation with heated ethanol was evaluated and the influence of amorphous content in the lactose powder prior to modification on powder properties, compaction behaviour and storage stability was determined. The modification process led to anhydrous alpha-lactose with decreased bulk and tapped density, increased flow rate and significantly higher specific surface area. Due to the higher specific surface area, the compaction behaviour of the anhydrous alpha-lactose was found to be significantly better than the compaction behaviour of powder blends consisting of alpha-lactose monohydrate and amorphous lactose. An influence of the amorphous content prior to modification could be observed only at higher compaction forces. In general, tablets of modified powders needed longer time to disintegrate directly after compression. However, the storage stability of modified tablets was found to be better compared to the amorphous-crystalline tablets which were influenced by storage conditions, initial crushing strength as well as amorphous content due to the re-crystallization of amorphous lactose during storage. 2009 Elsevier B.V. All rights reserved.

Systematic parameter inference in stochastic mesoscopic modeling

NASA Astrophysics Data System (ADS)

Lei, Huan; Yang, Xiu; Li, Zhen; Karniadakis, George Em

2017-02-01

We propose a method to efficiently determine the optimal coarse-grained force field in mesoscopic stochastic simulations of Newtonian fluid and polymer melt systems modeled by dissipative particle dynamics (DPD) and energy conserving dissipative particle dynamics (eDPD). The response surfaces of various target properties (viscosity, diffusivity, pressure, etc.) with respect to model parameters are constructed based on the generalized polynomial chaos (gPC) expansion using simulation results on sampling points (e.g., individual parameter sets). To alleviate the computational cost to evaluate the target properties, we employ the compressive sensing method to compute the coefficients of the dominant gPC terms given the prior knowledge that the coefficients are "sparse". The proposed method shows comparable accuracy with the standard probabilistic collocation method (PCM) while it imposes a much weaker restriction on the number of the simulation samples especially for systems with high dimensional parametric space. Fully access to the response surfaces within the confidence range enables us to infer the optimal force parameters given the desirable values of target properties at the macroscopic scale. Moreover, it enables us to investigate the intrinsic relationship between the model parameters, identify possible degeneracies in the parameter space, and optimize the model by eliminating model redundancies. The proposed method provides an efficient alternative approach for constructing mesoscopic models by inferring model parameters to recover target properties of the physics systems (e.g., from experimental measurements), where those force field parameters and formulation cannot be derived from the microscopic level in a straight forward way.

Functional characterization of normal and degraded bovine meniscus: Rate-dependent indentation and friction studies

PubMed Central

Baro, Vincent J.; Bonnevie, Edward D.; Lai, Xiaohan; Price, Christopher; Burris, David L.; Wang, Liyun

2013-01-01

The menisci are known to play important roles in normal joint function and the development of diseases such as osteoarthritis. However, our understanding of meniscus’ load bearing and lubrication properties at the tissue level remains limited. The objective of this investigation was to characterize the site- and rate-dependency of the compressive and frictional responses of the meniscus under a spherical contact load. Using a custom testing device, indentation tests with rates of 1, 10, 25, 50, and 100 μm/s were performed on bovine medial meniscus explants, which were harvested from five locations including the femoral apposing surface at the anterior, central, and posterior locations and the central portion at the deep layer and at the tibial apposing surface (n=5 per location). Sliding tests with rates of 0.05, 0.25, 1, and 5 mm/s were performed on the central femoral aspect and central tibial aspect superficial samples (n=6 per location). A separate set of superficial samples were subjected to papain digestion and tested prior to and post treatment. Our findings are: i) the Hertz contact model can be used to fit the force responses of meniscus under the conditions tested; ii) the anterior region is significantly stiffer than the posterior region and tissue modulus does not vary with tissue depth at the central region; iii) the friction coefficient of the meniscus is on the order of 0.02 under migratory contacts and the femoral apposing surface tends to show lower friction than the tibial apposing surface; iv) the meniscus exhibits increased modulus and lubrication with increased indentation and sliding rates; v) matrix degradation impedes the functional load support and lubrication properties of the tissue. The site- and rate-dependent properties of the meniscus may be attributed to spatial variations of the tissue’s biphasic structure. These properties substantiate the role of the meniscus as one of the important bearing surfaces of the knee. These data contribute to an improved understanding of meniscus function, and its role in degenerative joint diseases. In addition, the results provide functional metrics for developing engineered tissue replacements. PMID:22449445

Shape-Driven 3D Segmentation Using Spherical Wavelets

PubMed Central

Nain, Delphine; Haker, Steven; Bobick, Aaron; Tannenbaum, Allen

2013-01-01

This paper presents a novel active surface segmentation algorithm using a multiscale shape representation and prior. We define a parametric model of a surface using spherical wavelet functions and learn a prior probability distribution over the wavelet coefficients to model shape variations at different scales and spatial locations in a training set. Based on this representation, we derive a parametric active surface evolution using the multiscale prior coefficients as parameters for our optimization procedure to naturally include the prior in the segmentation framework. Additionally, the optimization method can be applied in a coarse-to-fine manner. We apply our algorithm to the segmentation of brain caudate nucleus, of interest in the study of schizophrenia. Our validation shows our algorithm is computationally efficient and outperforms the Active Shape Model algorithm by capturing finer shape details. PMID:17354875

The Nickel(111)/Alkaline Electrolyte Interface

NASA Technical Reports Server (NTRS)

Wang, Kuilong; Chottiner, G. S.; Scherson, D. A.; Reid, Margaret A.

1991-01-01

The electrochemical properties of Ni (111) prepared and characterized in ultra high vacuum, UHV, by surface analytical techniques have been examined in alkaline media by cyclic voltammetry using an UHV-electrochemical cell transfer system designed and built in this laboratory. Prior to the transfer, the Ni(111) surfaces were exposed to saturation coverages of CO in UHV in an attempt to protect the surface from possible contamination with other gases during the transfer. Temperature Programmed Desorption, TPD, of CO-dosed Ni (111) surfaces displaying sharp c(4x2), LEED patterns, subsequently exposed to water-saturated Ar at atmospheric pressure in an auxiliary UHV compatible chamber and finally transferred back to the main UHV chamber, yielded CO2 and water as the only detectable products. This indicates that the CO-dosed surfaces react with water and/or bicarbonate and hydroxide as the most likely products. Based on the integration of the TPD peaks, the combined amounts of H2O and CO2 were found to be on the order of a single monolayer. The reacted c(4x2)CO/Ni(111) layer seems to protect the surface from undergoing spontaneous oxidation in strongly alkaline solutions. This was evidenced by the fact that the open circuit potential observed immediately after contact with deaerated 0.1 M KOH was about 0.38 V vs. DHE, drifting slightly towards more negative values prior to initiating the voltametric scans. The average ratio of the integrated charge obtained in the first positive linear scan in the range of 0.35 to 1.5 V vs. DHE (initiated at the open circuit potential) and the first (and subsequent) linear negative scans in the same solution yielded for various independent runs a value of 3.5 +/- 0.3. Coulometric analysis of the cyclic voltammetry curves indicate that the electrochemically formed oxyhydroxide layer involves a charge equivalent to 3.2 +/- 0.4 layers of Ni metal.

The effects of local forearm muscle cooling on motor unit properties.

PubMed

Mallette, Matthew M; Green, Lara A; Gabriel, David A; Cheung, Stephen S

2018-02-01

Muscle cooling impairs maximal force. Using needle electromyography (EMG) to assess motor unit properties during muscle cooling, is limited and equivocal. Therefore, we aimed to determine the impact of local muscle cooling on motor unit firing properties using surface EMG decomposition. Twenty participants (12 M, 8 F) completed maximal, evoked, and trapezoidal contractions during thermoneutral and cold muscle conditions. Forearm muscle temperature was manipulated using 10-min neutral (~ 32 °C) or 20-min cold (~ 3 °C) water baths. Twitches and maximal voluntary contractions were performed prior to, and after, forearm immersion in neutral or cold water. Motor unit properties were assessed during trapezoidal contractions to 50% baseline force using surface EMG decomposition. Impaired contractile properties from muscle cooling were evident in the twitch amplitude, duration, and rate of force development indicating that the muscle was successfully cooled from the cold water bath (all d ≥ 0.5, P < 0.05). Surface EMG decomposition showed muscle cooling increased the number of motor units (d = 0.7, P = 0.01) and motor unit action potential (MUAP) duration (d = 0.6, P < 0.001), but decreased MUAP amplitude (d = 0.2, P = 0.012). Individually, neither motor unit firing rates (d = 0.1, P = 0.843) nor recruitment threshold (d = 0.1, P = 0.746) changed; however, the relationship between the recruitment threshold and motor unit firing rate was steeper (d = 1.0, P < 0.001) and had an increased y-intercept (d = 0.9, P = 0.007) with muscle cooling. Since muscle contractility is impaired with muscle cooling, these findings suggest a compensatory increase in the number of active motor units, and small but coupled changes in motor unit firing rates and recruitment threshold to produce the same force.

The power prior: theory and applications.

PubMed

Ibrahim, Joseph G; Chen, Ming-Hui; Gwon, Yeongjin; Chen, Fang

2015-12-10

The power prior has been widely used in many applications covering a large number of disciplines. The power prior is intended to be an informative prior constructed from historical data. It has been used in clinical trials, genetics, health care, psychology, environmental health, engineering, economics, and business. It has also been applied for a wide variety of models and settings, both in the experimental design and analysis contexts. In this review article, we give an A-to-Z exposition of the power prior and its applications to date. We review its theoretical properties, variations in its formulation, statistical contexts for which it has been used, applications, and its advantages over other informative priors. We review models for which it has been used, including generalized linear models, survival models, and random effects models. Statistical areas where the power prior has been used include model selection, experimental design, hierarchical modeling, and conjugate priors. Frequentist properties of power priors in posterior inference are established, and a simulation study is conducted to further examine the empirical performance of the posterior estimates with power priors. Real data analyses are given illustrating the power prior as well as the use of the power prior in the Bayesian design of clinical trials. Copyright © 2015 John Wiley & Sons, Ltd.

Asphalt additives in thick hot mixed asphalt-concrete pavements. Research report (Interim), Sep 86-Oct 90

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

Button, J.W.; Prapnnachari, S.

Asphalt concrete field test pavements were placed in District 19 north of Texarkana on US-59/71 in 1987 and 1988 to evaluate the ability of certain asphalt additives to enhance resistance to cracking and rutting. Two 10-inch thick and 0.9 mile (approx.) long test pavements and a similar untreated control section were constructed in the northbound and southbound lanes for a total of 6 field trials. Asphalt additives were incorporated in both the 8-inch base and the overlying 2-inch surface layers. The additives evaluated included Goodyear LPF 5812, Chemkrete-CTI 102, Exxon Polybilt 102, and Styrelf 13. Samples of paving materials includingmore » aggregates, asphalts, compacted mixes, and pavement cores were collected, conveyed to the laboratory, and tested to provide detailed documentation of their properties. Tests included rheological properties of the binders before and after artificial aging, characterization of aggregate, Hveem and Marshall stability, stiffness as a function of temperature, tensile properties before and after moisture conditioning and artificial aging, air void content, creep, and permanent deformation. Field tests and visual evaluations have been conducted to objectively evaluate field performance. Results of these tests are reported herein. Within 6 months after construction of the base layers and prior to placement of the surface course, the Chemkrete modified base became severely cracked. As a result, the surface mix placed on this base section was treated with Goodyear latex rather than Chemkrete. All other modified pavements and the control section have performed well and exhibited essentially equivalent performance after 2 1/2 years in service.« less

Development of high-viscosity, two-paste bioactive bone cements.

PubMed

Deb, S; Aiyathurai, L; Roether, J A; Luklinska, Z B

2005-06-01

Self-curing two-paste bone cements have been developed using methacrylate monomers with a view to formulate cements with low polymerization exotherm, low shrinkage, better mechanical properties, and improved adhesion to bone and implant surfaces. The monomers include bis-phenol A glycidyl dimethacrylate (bis-GMA), urethane dimethacrylate (UDMA) and triethylene glycol dimethacrylate (TEGDMA) as a viscosity modifier. Two-paste systems were formulated containing 60% by weight of a bioactive ceramic, hydroxyapatite. A methacroyloxy silane (A174) was used as a coupling agent due to its higher water stability in comparison to other aminosilanes to silanate the hydroxyapatite particles prior to composite formulation. A comparison of the FT-infrared spectrum of hydroxyapatite and silanated hydroxyapatite showed the presence of the carbonyl groups ( approximately 1720 cm(-1)), -C=C-( approximately 1630 cm(-1)) and Si-O- (1300-1250 cm(-1)) which indicated the availability of silane groups on the filler surface. Two methods of mixing were effected to form the bone cement: firstly by mixing in an open bowl and secondly by extruding the two pastes by an auto-mixing tip using a gun to dispense the pastes. Both types of cements yielded low polymerization exotherms with good mechanical properties; however, the lower viscosity of UDMA allowed better extrusion and handling properties. A biologically active apatite layer formed on the bone cement surface within a short period after its immersion in simulated body fluid, demonstrating in vitro bioactivity of the composite. This preliminary data thus suggests that UDMA is a viable alternative to bis-GMA as a polymerizable matrix in the formation of bone cements.

Locating landmarks on high-dimensional free energy surfaces

PubMed Central

Chen, Ming; Yu, Tang-Qing; Tuckerman, Mark E.

2015-01-01

Coarse graining of complex systems possessing many degrees of freedom can often be a useful approach for analyzing and understanding key features of these systems in terms of just a few variables. The relevant energy landscape in a coarse-grained description is the free energy surface as a function of the coarse-grained variables, which, despite the dimensional reduction, can still be an object of high dimension. Consequently, navigating and exploring this high-dimensional free energy surface is a nontrivial task. In this paper, we use techniques from multiscale modeling, stochastic optimization, and machine learning to devise a strategy for locating minima and saddle points (termed “landmarks”) on a high-dimensional free energy surface “on the fly” and without requiring prior knowledge of or an explicit form for the surface. In addition, we propose a compact graph representation of the landmarks and connections between them, and we show that the graph nodes can be subsequently analyzed and clustered based on key attributes that elucidate important properties of the system. Finally, we show that knowledge of landmark locations allows for the efficient determination of their relative free energies via enhanced sampling techniques. PMID:25737545

High quality of InAsSb epilayer with cutoff wavelength longer than 10 μm grown on GaAs by the modified LPE technique

NASA Astrophysics Data System (ADS)

Hu, S. H.; Sun, C. H.; Sun, Y.; Ge, J.; Wang, R.; Wu, J.; Wang, Q. W.; Dai, N.

2009-04-01

The InAsSb epilayers with a cutoff wavelength of 11.5 μm were successfully grown on highly lattice-mismatched semi-insulating (1 0 0) GaAs substrate by the modified liquid phase epitaxy (LPE) technique. Fourier transform infrared (FTIR) transmission spectrum revealed a strong band gap narrowing for this alloy. The electrical properties were investigated by the Van der Pauw measurements at 300 and 77 K. InAsSb epilayers showed high Hall mobilities being 11,800 cm 2/V s at room temperature (RT). After an annealing treament for 10 h, the electron mobility at 77 K were improved from 1730 cm 2/V s (prior to annealing) to 13,470 cm 2/V s. Wet etching was used to display the surface etch pits prior to and after annealing treatment, showing that the mobility improvement was due to the reduction of the etch pits density.

50 CFR 12.32 - Effect of prior illegality.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 1 2010-10-01 2010-10-01 false Effect of prior illegality. 12.32 Section... PLANTS SEIZURE AND FORFEITURE PROCEDURES Disposal of Forfeited or Abandoned Property § 12.32 Effect of prior illegality. The effect of any prior illegality on a subsequent holder of any wildlife or plant...

On the petrological, geochemical, and geophysical characterization of a returned Mars surface sample and the impact of biological sterilization on the analyses

NASA Technical Reports Server (NTRS)

1974-01-01

A study was conducted: to identify those experiments that could and should be done on a returned Martian sample in order to characterize its inorganic properties; to evaluate, insofar as can be done, the effects of potential biological sterilization of the sample by heating prior to its return; to identify particular analytical techniques needing further improvement in order to make optimum use of a returned sample; and to identify experiments to be done on simulants, with and without sterilization, that better define the limits of information available about the planet from analyses of returned samples.

Universal timescales in the rheology of spheroid cell aggregates

NASA Astrophysics Data System (ADS)

Yu, Miao; Mahtabfar, Aria; Beleen, Paul; Foty, Ramsey; Zahn, Jeffrey; Shreiber, David; Liu, Liping; Lin, Hao

2017-11-01

The rheological properties of tissue play important roles in key biological processes including embryogenesis, cancer metastasis, and wound healing. Spheroid cell aggregate is a particularly interesting model system for the study of these phenomena. In the long time, they behave like drops with a surface tension. In the short, viscoelasticity also needs to be considered. In this work, we discover two coupled and universal timescales for spheroid aggregates. A total of 12 aggregate types (total aggregate number n =290) derived from L and GBM (glioblastoma multiforme) cells are studied with microtensiometer to obtain their surface tension. They are also allowed to relax upon release of the compression forces. The two timescales are observed during the relaxation process; their values do not depend on compression time nor the degree of deformation, and are consistent among all 12 types. Following prior work (Yu et al., Phys. Rev. Lett., 115:128303; Liu et al., J. Mech. Phys. Solids, 98:309-329) we use a rigorous mathematical theory to interpret the results, which reveals intriguing properties of the aggregates on both tissue and cellular levels. The mechanics of multicellular organization reflects both complexity and regularity due to strong active regulation.

Magnetic properties and macroscopic heterogeneity of FeCoNbB Hitperms

NASA Astrophysics Data System (ADS)

Butvin, Pavol; Butvinová, Beata; Sitek, Jozef; Degmová, Jarmila; Vlasák, Gabriel; Švec, Peter; Janičkovič, Dušan

Nanocrystalline ribbons of Fe 81-xCo xNb 7B 12 (where x ranges from 0 to 40.5 at%) Hitperm alloys have been investigated as to their basic magnetic properties and the influence of the macroscopic heterogeneity. Different crystalline share at surfaces compared with the volume average is observed by conversion electron Mössbauer spectroscopy (CEMS) and Mössbauer spectroscopy (MS), respectively. This marks the presence of macroscopic heterogeneity in these Hitperms. The heterogeneity is generally more significant in Ar-annealed samples than in the vacuum-annealed ones. The characteristic slant hysteresis loops (hard-ribbon-axis) are seen as a rule with few exceptions. An inspection of hysteresis loop response of resin potted samples shows that the surfaces bi-axially squeeze the ribbon interior in heterogeneous Hitperms when the ribbons cool down after annealing. Certain compositions show macroscopic viscous flow prior to crystallization so the heterogeneity gets another chance to induce anisotropy during annealing. The induction attains 1.5 T but saturates poorly due to the heterogeneity and the ensuing anisotropy. Moreover the heterogeneity appears to hamper the crystallization within the ribbon interior. Unlike Finemets, the density of these Hitperms show no pronounced trend with annealing.

Sources and properties of non-exhaust particulate matter from road traffic: a review.

PubMed

Thorpe, Alistair; Harrison, Roy M

2008-08-01

While emissions control regulation has led to a substantial reduction in exhaust emissions from road traffic, currently non-exhaust emissions from road vehicles are unabated. These include particles from brake wear, tyre wear, road surface abrasion and resuspension in the wake of passing traffic. Quantification of the magnitude of such emissions is problematic both in the laboratory and the field and the latter depends heavily upon a knowledge of the physical and chemical properties of non-exhaust particles. This review looks at each source in turn, reviewing the available information on the source materials and particles derived from them in laboratory studies. In a final section, some of the key publications dealing with measurements in road tunnels and the roadside environment are reviewed. It is concluded that with the exception of brake dust particles which may be identified from their copper (Cu) and antimony (Sb) content, unequivocal identification of particles from other sources is likely to prove extremely difficult, either because of the lack of suitable tracer elements or compounds, or because of the interactions between sources prior to the emission process. Even in the case of brake dust, problems will arise in distinguishing directly emitted particles from those arising from resuspension of deposited brake dust from the road surface, or that derived from entrainment of polluted roadside soils, either directly or as a component of road surface dust.

Transpiration purged optical probe

DOEpatents

VanOsdol, John; Woodruff, Steven

2004-01-06

An optical apparatus for clearly viewing the interior of a containment vessel by applying a transpiration fluid to a volume directly in front of the external surface of the optical element of the optical apparatus. The fluid is provided by an external source and transported by means of an annular tube to a capped end region where the inner tube is perforated. The perforation allows the fluid to stream axially towards the center of the inner tube and then axially away from an optical element which is positioned in the inner tube just prior to the porous sleeve. This arrangement draws any contaminants away from the optical element keeping it free of contaminants. In one of several embodiments, the optical element can be a lens, a viewing port or a laser, and the external source can provide a transpiration fluid having either steady properties or time varying properties.

26 CFR 1.197-1T - Certain elections for intangible property (temporary).

Code of Federal Regulations, 2010 CFR

2010-04-01

...) to apply prior law to property acquired pursuant to a written binding contract in effect on August 10... section 13261 of OBRA '93 (e.g., the amendment of section 1253 in the case of a franchise, trademark, or... section 197 intangible with an unadjusted basis of $180. Under prior law, no amortization or depreciation...

Enhancing the Stiffness of Electrospun Nanofiber Scaffolds with Controlled Surface Coating and Mineralization

PubMed Central

Liu, Wenying; Yeh, Yi-Chun; Lipner, Justin; Xie, Jingwei; Sung, Hsing-Wen; Thomopoulos, Stavros; Xia, Younan

2011-01-01

A new method was developed to coat hydroxyapatite (HAp) onto electrospun poly(lactic-co-glycolic acid) (PLGA) nanofibers for tendon-to-bone insertion site repair applications. Prior to mineralization, chitosan and heparin were covalently immobilized onto the surface of the fibers to accelerate the nucleation of bone-like HAp crystals. Uniform coatings of HAp were obtained by immersing the nanofiber scaffolds into a modified 10 times concentrated simulated body fluid (m10SBF) for different periods of time. The new method resulted in thicker and denser coatings of mineral on the fibers compared to previously reported methods. Scanning electron microscopy measurements confirmed the formation of nanoscale HAp particles on the fibers. Mechanical property assessment demonstrated higher stiffness with respect to previous coating methods. A combination of the nanoscale fibrous structure and bone-like mineral coating could mimic the structure, composition, and function of mineralized tissues. PMID:21710996

An Evaluation of Pixel-Based Methods for the Detection of Floating Objects on the Sea Surface

NASA Astrophysics Data System (ADS)

Borghgraef, Alexander; Barnich, Olivier; Lapierre, Fabian; Van Droogenbroeck, Marc; Philips, Wilfried; Acheroy, Marc

2010-12-01

Ship-based automatic detection of small floating objects on an agitated sea surface remains a hard problem. Our main concern is the detection of floating mines, which proved a real threat to shipping in confined waterways during the first Gulf War, but applications include salvaging, search-and-rescue operation, perimeter, or harbour defense. Detection in infrared (IR) is challenging because a rough sea is seen as a dynamic background of moving objects with size order, shape, and temperature similar to those of the floating mine. In this paper we have applied a selection of background subtraction algorithms to the problem, and we show that the recent algorithms such as ViBe and behaviour subtraction, which take into account spatial and temporal correlations within the dynamic scene, significantly outperform the more conventional parametric techniques, with only little prior assumptions about the physical properties of the scene.

High-performance super capacitors based on activated anthracite with controlled porosity

NASA Astrophysics Data System (ADS)

Lee, Hyun-Chul; Byamba-Ochir, Narandalai; Shim, Wang-Geun; Balathanigaimani, M. S.; Moon, Hee

2015-02-01

Mongolian anthracite is chemically activated using potassium hydroxide as an activation agent to make activated carbon materials. Prior to the chemical activation, the chemical agent is introduced by two different methods as follows, (1) simple physical mixing, (2) impregnation. The physical properties such as specific surface area, pore volume, pore size distribution, and adsorption energy distribution are measured to assess them as carbon electrode materials for electric double-layer capacitors (EDLC). The surface functional groups and morphology are also characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analyses respectively. The electrochemical results for the activated carbon electrodes in 3 M sulfuric acid electrolyte solution indicate that the activated Mongolian anthracite has relatively large specific capacitances in the range of 120-238 F g-1 and very high electrochemical stability, as they keep more than 98% of initial capacitances until 1000 charge/discharge cycles.

MitoQ Loaded Chitosan-Hyaluronan Composite Membranes for Wound Healing

PubMed Central

Tamer, Tamer M.; Collins, Maurice N.; Valachová, Katarina; Hassan, Mohamed A.; Omer, Ahmed M.; Mohy-Eldin, Mohamed S.; Švík, Karol; Jurčík, Rastislav; Ondruška, Ľubomír; Biró, Csaba; Albadarin, Ahmad B.; Šoltés, Ladislav

2018-01-01

Two self-associating biopolymers, namely chitosan (Ch) and a high-molar-mass hyaluronan (HA), were used to prepare membranes with the aim to protect and to enhance the healing of injured skin. A mitochondrially-targeted antioxidant—MitoQ—was incorporated into the mixture of biopolymers prior to their self-association. These three-component membranes were evaluated in detail utilising surface roughness measurements, contact angle measurements, hemocompatibility, and thrombogenicity analyses. Furthermore, in vivo application of Ch/HA/MitoQ membranes was assessed on injured rabbit and rat skin utilizing histological methods. The results showed that the prepared thrombogenic Ch/HA/MitoQ membranes had higher roughness, which allowed for greater surface area for tissue membrane interaction during the healing processes, and lower cytotoxicity levels than controls. MitoQ-loaded composite membranes displayed superior healing properties in these animal models compared to control membranes. PMID:29642447

MitoQ Loaded Chitosan-Hyaluronan Composite Membranes for Wound Healing.

PubMed

Tamer, Tamer M; Collins, Maurice N; Valachová, Katarina; Hassan, Mohamed A; Omer, Ahmed M; Mohy-Eldin, Mohamed S; Švík, Karol; Jurčík, Rastislav; Ondruška, Ľubomír; Biró, Csaba; Albadarin, Ahmad B; Šoltés, Ladislav

2018-04-07

Two self-associating biopolymers, namely chitosan (Ch) and a high-molar-mass hyaluronan (HA), were used to prepare membranes with the aim to protect and to enhance the healing of injured skin. A mitochondrially-targeted antioxidant-MitoQ-was incorporated into the mixture of biopolymers prior to their self-association. These three-component membranes were evaluated in detail utilising surface roughness measurements, contact angle measurements, hemocompatibility, and thrombogenicity analyses. Furthermore, in vivo application of Ch/HA/MitoQ membranes was assessed on injured rabbit and rat skin utilizing histological methods. The results showed that the prepared thrombogenic Ch/HA/MitoQ membranes had higher roughness, which allowed for greater surface area for tissue membrane interaction during the healing processes, and lower cytotoxicity levels than controls. MitoQ-loaded composite membranes displayed superior healing properties in these animal models compared to control membranes.

The effects of argon ion bombardment on the corrosion resistance of tantalum

NASA Astrophysics Data System (ADS)

Ramezani, A. H.; Sari, A. H.; Shokouhy, A.

2017-02-01

Application of ion beam has been widely used as a surface modification method to improve surface properties. This paper investigates the effect of argon ion implantation on surface structure as well as resistance against tantalum corrosion. In this experiment, argon ions with energy of 30 keV and in doses of 1 × 1017-10 × 1017 ions/cm2 were used. The surface bombardment with inert gases mainly produces modified topography and morphology of the surface. Atomic Force Microscopy was also used to patterned the roughness variations prior to and after the implantation phase. Additionally, the corrosion investigation apparatus wear was applied to compare resistance against tantalum corrosion both before and after ion implantation. The results show that argon ion implantation has a substantial impact on increasing resistance against tantalum corrosion. After the corrosion test, scanning electron microscopy (SEM) analyzed the samples' surface morphologies. In addition, the elemental composition is characterized by energy-dispersive X-ray (EDX) analysis. The purpose of this paper was to obtain the perfect condition for the formation of tantalum corrosion resistance. In order to evaluate the effect of the ion implantation on the corrosion behavior, potentiodynamic tests were performed. The results show that the corrosion resistance of the samples strongly depends on the implantation doses.

Land Surface Microwave Emissivities Derived from AMSR-E and MODIS Measurements with Advanced Quality Control

NASA Technical Reports Server (NTRS)

Moncet, Jean-Luc; Liang, Pan; Galantowicz, John F.; Lipton, Alan E.; Uymin, Gennady; Prigent, Catherine; Grassotti, Christopher

2011-01-01

A microwave emissivity database has been developed with data from the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and with ancillary land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the same Aqua spacecraft. The primary intended application of the database is to provide surface emissivity constraints in atmospheric and surface property retrieval or assimilation. An additional application is to serve as a dynamic indicator of land surface properties relevant to climate change monitoring. The precision of the emissivity data is estimated to be significantly better than in prior databases from other sensors due to the precise collocation with high-quality MODIS LST data and due to the quality control features of our data analysis system. The accuracy of the emissivities in deserts and semi-arid regions is enhanced by applying, in those regions, a version of the emissivity retrieval algorithm that accounts for the penetration of microwave radiation through dry soil with diurnally varying vertical temperature gradients. These results suggest that this penetration effect is more widespread and more significant to interpretation of passive microwave measurements than had been previously established. Emissivity coverage in areas where persistent cloudiness interferes with the availability of MODIS LST data is achieved using a classification-based method to spread emissivity data from less-cloudy areas that have similar microwave surface properties. Evaluations and analyses of the emissivity products over homogeneous snow-free areas are presented, including application to retrieval of soil temperature profiles. Spatial inhomogeneities are the largest in the vicinity of large water bodies due to the large water/land emissivity contrast and give rise to large apparent temporal variability in the retrieved emissivities when satellite footprint locations vary over time. This issue will be dealt with in the future by including a water fraction correction. Also note that current reliance on the MODIS day-night algorithm as a source of LST limits the coverage of the database in the Polar Regions. We will consider relaxing the current restriction as part of future development.

Spectral Remote Sensing of Dust Sources on the U.S. Great Plains from 1930s Panchromatic Aerial Phtography

NASA Astrophysics Data System (ADS)

Bolles, K.; Forman, S. L.

2017-12-01

Understanding the spatiotemporal dynamics of dust sources is essential to accurately quantify the various impacts of dust on the Earth system; however, a persistent deficiency in modeling dust emission is detailed knowledge of surface texture, geomorphology, and location of dust emissive surfaces, which strongly influence the effects of wind erosion. Particle emission is closely linked to both climatic and physical surface factors - interdependent variables that respond to climate nonlinearly and are mitigated by variability in land use or management practice. Recent efforts have focused on development of a preferential dust source (PDS) identification scheme to improve global dust-cycle models, which posits certain surfaces are more likely to emit dust than others, dependent upon associated sediment texture and geomorphological limitations which constrain sediment supply and availability. In this study, we outline an approach to identify and verify the physical properties and distribution of dust emissive surfaces in the U.S. Great Plains from historical aerial imagery in order to establish baseline records of dust sources, associated erodibility, and spatiotemporal variability, prior to the satellite era. We employ a multi-criteria, spatially-explicit model to identify counties that are "representative" of the broader landscape on the Great Plains during the 1930s. Parameters include: percentage of county cultivated and uncultivated per the 1935 Agricultural Census, average soil sand content, mean annual Palmer Drought Severity Index (PDSI), maximum annual temperature and percent difference to the 30-year normal maximum temperature, and annual precipitation and percent difference to the 30-year normal precipitation level. Within these areas we generate random points to select areas for photo reproduction. Selected frames are photogrammetrically scanned at 1200 dpi, radiometrically corrected, mosaicked and georectified to create an IKONOS-equivalent image. Gray-level co-occurrence matrices are calculated in a 3x3 moving window to determine textural properties of the mosaic and delineate bare surfaces of different sedimentological properties. Field stratigraphic assessments and spatially-referenced historical data are integrated within ArcGIS to ground-truth imagery.

Analysis of the Effects of Vitiates on Surface Heat Flux in Ground Tests of Hypersonic Vehicles

NASA Technical Reports Server (NTRS)

Cuda, Vincent; Gaffney, Richard L

2008-01-01

To achieve the high enthalpy conditions associated with hypersonic flight, many ground test facilities burn fuel in the air upstream of the test chamber. Unfortunately, the products of combustion contaminate the test gas and alter gas properties and the heat fluxes associated with aerodynamic heating. The difference in the heating rates between clean air and a vitiated test medium needs to be understood so that the thermal management system for hypersonic vehicles can be properly designed. This is particularly important for advanced hypersonic vehicle concepts powered by air-breathing propulsion systems that couple cooling requirements, fuel flow rates, and combustor performance by flowing fuel through sub-surface cooling passages to cool engine components and preheat the fuel prior to combustion. An analytical investigation was performed comparing clean air to a gas vitiated with methane/oxygen combustion products to determine if variations in gas properties contributed to changes in predicted heat flux. This investigation started with simple relationships, evolved into writing an engineering-level code, and ended with running a series of CFD cases. It was noted that it is not possible to simultaneously match all of the gas properties between clean and vitiated test gases. A study was then conducted selecting various combinations of freestream properties for a vitiated test gas that matched clean air values to determine which combination of parameters affected the computed heat transfer the least. The best combination of properties to match was the free-stream total sensible enthalpy, dynamic pressure, and either the velocity or Mach number. This combination yielded only a 2% difference in heating. Other combinations showed departures of up to 10% in the heat flux estimate.

Good News for Borehole Climatology

NASA Astrophysics Data System (ADS)

Rath, Volker; Fidel Gonzalez-Rouco, J.; Goosse, Hugues

2010-05-01

Though the investigation of observed borehole temperatures has proved to be a valuable tool for the reconstruction of ground surface temperature histories, there are many open questions concerning the significance and accuracy of the reconstructions from these data. In particular, the temperature signal of the warming after the Last glacial Maximum (LGM) is still present in borehole temperature profiles. It influences the relatively shallow boreholes used in current paleoclimate inversions to estimate temperature changes in the last centuries. This is shown using Monte Carlo experiments on past surface temperature change, using plausible distributions for the most important parameters, i.e.,amplitude and timing of the glacial-interglacial transition, the prior average temperature, and petrophysical properties. It has been argued that the signature of the last glacial-interglacial transition could be responsible for the high amplitudes of millennial temperature reconstructions. However, in shallow boreholes the additional effect of past climate can reasonably approximated by a linear variation of temperature with depth, and thus be accommodated by a "biased" background heat flow. This is good news for borehole climate, but implies that the geological heat flow values have to be interpreted accordingly. Borehole climate reconstructions from these shallow are most probably underestimating past variability due to the diffusive character of the heat conduction process, and the smoothness constraints necessary for obtaining stable solutions of this ill-posed inverse problem. A simple correction based on subtracting an appropriate prior surface temperature history shows promising results reducing these errors considerably, also with deeper boreholes, where the heat flow signal can not be approximated linearly, and improves the comparisons with AOGCM modeling results.

Hysteresis as an Implicit Prior in Tactile Spatial Decision Making

PubMed Central

Thiel, Sabrina D.; Bitzer, Sebastian; Nierhaus, Till; Kalberlah, Christian; Preusser, Sven; Neumann, Jane; Nikulin, Vadim V.; van der Meer, Elke; Villringer, Arno; Pleger, Burkhard

2014-01-01

Perceptual decisions not only depend on the incoming information from sensory systems but constitute a combination of current sensory evidence and internally accumulated information from past encounters. Although recent evidence emphasizes the fundamental role of prior knowledge for perceptual decision making, only few studies have quantified the relevance of such priors on perceptual decisions and examined their interplay with other decision-relevant factors, such as the stimulus properties. In the present study we asked whether hysteresis, describing the stability of a percept despite a change in stimulus property and known to occur at perceptual thresholds, also acts as a form of an implicit prior in tactile spatial decision making, supporting the stability of a decision across successively presented random stimuli (i.e., decision hysteresis). We applied a variant of the classical 2-point discrimination task and found that hysteresis influenced perceptual decision making: Participants were more likely to decide ‘same’ rather than ‘different’ on successively presented pin distances. In a direct comparison between the influence of applied pin distances (explicit stimulus property) and hysteresis, we found that on average, stimulus property explained significantly more variance of participants’ decisions than hysteresis. However, when focusing on pin distances at threshold, we found a trend for hysteresis to explain more variance. Furthermore, the less variance was explained by the pin distance on a given decision, the more variance was explained by hysteresis, and vice versa. Our findings suggest that hysteresis acts as an implicit prior in tactile spatial decision making that becomes increasingly important when explicit stimulus properties provide decreasing evidence. PMID:24587045

Effect of Cl2 plasma treatment and annealing on vanadium based metal contacts to Si-doped Al0.75Ga0.25N

NASA Astrophysics Data System (ADS)

Lapeyrade, Mickael; Alamé, Sabine; Glaab, Johannes; Mogilatenko, Anna; Unger, Ralph-Stephan; Kuhn, Christian; Wernicke, Tim; Vogt, Patrick; Knauer, Arne; Zeimer, Ute; Einfeldt, Sven; Weyers, Markus; Kneissl, Michael

2017-09-01

In order to understand the electrical properties of V/Al/Ni/Au metal contacts to Si-doped Al0.75Ga0.25N layers, X-ray photoelectron spectroscopy analysis was performed on differently treated AlGaN:Si surfaces before metal deposition, and transmission electron microscopy was used to study the semiconductor-metal interface after contact annealing at 900 °C. Cl2 plasma etching of AlGaN increases the aluminum/nitrogen ratio at the surface, and Al oxide or oxynitride is always formed by any surface treatment applied after etching. After contact annealing, a complex interface structure including amorphous AlOx and different metal phases such as Al-Au-Ni, V-Al, and V2N were found. The electrical properties of the contacts were determined by thermionic emission and/or thermionic field emission in the low voltage regime. Nearly ohmic contacts on AlGaN surfaces exposed to a Cl2 plasma were only obtained by annealing the sample at a temperature of 815 °C under N2/NH3 prior to metallization. By this treatment, the oxygen contamination on the surface could be minimized, resulting in a larger semiconductor area to be in direct contact with metal phases such as Al-rich Al-Au-Ni or V-Al and leading to a contact resistivity of 2.5 × 10-2 Ω cm2. This treatment can be used to significantly reduce the operating voltage of current deep ultraviolet light emitting diodes which will increase their wall plug efficiency and lower the thermal stress during their operation.

The surface latent heat flux anomalies related to major earthquake

NASA Astrophysics Data System (ADS)

Jing, Feng; Shen, Xuhui; Kang, Chunli; Xiong, Pan; Hong, Shunying

2011-12-01

SLHF (Surface Latent Heat Flux) is an atmospheric parameter, which can describe the heat released by phase changes and dependent on meteorological parameters such as surface temperature, relative humidity, wind speed etc. There is a sharp difference between the ocean surface and the land surface. Recently, many studies related to the SLHF anomalies prior to earthquakes have been developed. It has been shown that the energy exchange enhanced between coastal surface and atmosphere prior to earthquakes can increase the rate of the water-heat exchange, which will lead to an obviously increases in SLHF. In this paper, two earthquakes in 2010 (Haiti earthquake and southwest of Sumatra in Indonesia earthquake) have been analyzed using SLHF data by STD (standard deviation) threshold method. It is shows that the SLHF anomaly may occur in interpolate earthquakes or intraplate earthquakes and coastal earthquakes or island earthquakes. And the SLHF anomalies usually appear 5-6 days prior to an earthquake, then disappear quickly after the event. The process of anomaly evolution to a certain extent reflects a dynamic energy change process about earthquake preparation, that is, weak-strong-weak-disappeared.

Inferring internal properties of Earth's core dynamics and their evolution from surface observations and a numerical geodynamo model

NASA Astrophysics Data System (ADS)

Aubert, J.; Fournier, A.

2011-10-01

Over the past decades, direct three-dimensional numerical modelling has been successfully used to reproduce the main features of the geodynamo. Here we report on efforts to solve the associated inverse problem, aiming at inferring the underlying properties of the system from the sole knowledge of surface observations and the first principle dynamical equations describing the convective dynamo. To this end we rely on twin experiments. A reference model time sequence is first produced and used to generate synthetic data, restricted here to the large-scale component of the magnetic field and its rate of change at the outer boundary. Starting from a different initial condition, a second sequence is next run and attempts are made to recover the internal magnetic, velocity and buoyancy anomaly fields from the sparse surficial data. In order to reduce the vast underdetermination of this problem, we use stochastic inversion, a linear estimation method determining the most likely internal state compatible with the observations and some prior knowledge, and we also implement a sequential evolution algorithm in order to invert time-dependent surface observations. The prior is the multivariate statistics of the numerical model, which are directly computed from a large number of snapshots stored during a preliminary direct run. The statistics display strong correlation between different harmonic degrees of the surface observations and internal fields, provided they share the same harmonic order, a natural consequence of the linear coupling of the governing dynamical equations and of the leading influence of the Coriolis force. Synthetic experiments performed with a weakly nonlinear model yield an excellent quantitative retrieval of the internal structure. In contrast, the use of a strongly nonlinear (and more realistic) model results in less accurate static estimations, which in turn fail to constrain the unobserved small scales in the time integration of the evolution scheme. Evaluating the quality of forecasts of the system evolution against the reference solution, we show that our scheme can improve predictions based on linear extrapolations on forecast horizons shorter than the system e-folding time. Still, in the perspective of forthcoming data assimilation activities, our study underlines the need of advanced estimation techniques able to cope with the moderate to strong nonlinearities present in the geodynamo.

Microstructural and Morphological Factors Affecting Uncertainty in Small Scale Mechanical Properties

NASA Astrophysics Data System (ADS)

Maughan, Michael R.

If materials are to be developed from the ground up, the process will be dependent upon accurate and well-defined models of material behavior. These models can be closed-form solutions developed from first principles, simulations, or empirically derived equations, among others. Material behavior at the mesoscale is in general well understood, having had several centuries of study. However, behavior at the micro or nanoscale still requires characterization. Understanding the collective influence of the microstructure on the bulk material, for example with models like the Hall-Petch relation, has advanced our ability to manipulate the material to our advantage. We now have the ability to study not only the structure of the material, but also the material behavior and properties at the nanoscale. Understanding this behavior is critical to developing a framework for interpreting and utilizing these properties in materials design. This research aims to improve the fundamental understanding of the mechanical performance of materials and the subsequent variation in measured properties. The literature reports widely varying material properties such as hardness, elastic modulus, and yield point when measured at the nanoscale. Proposed variation mechanisms in these properties include surface preparation, error in measurement, heterogeneous dislocation density and distribution, crystal orientation, surface oxide film fracture, and others. Among other things, this work shows that these sources of variation can be determined and quantified, and that this information can be utilized as a characterization and/or predictive tool. The main goals of this work are to 1) continue basic research on sources of variation in the nanoscale properties of materials, specifically hardness and modulus in crystalline and glassy solids, 2) study the abrupt transition from elastic to plastic material behavior known as pop-in and resolve the problem of pseudo-elastic behavior prior to plasticity, and 3) integrate the sources of and propagate the variation into materials simulations, 4) study the influence of dislocation processes on indentation size effects, and 5) apply this learning to difficult to measure or interpret materials applications.

Effect of repeated sterilization cycles on the physical properties of scaling instruments: a scanning electron microscopy study.

PubMed

Porto, Alessandra Nogueira; Borges, Álvaro Henrique; Semenoff-Segundo, Alex; Raslan, Suzane A; Pedro, Fábio Luis Miranda; Jorge, Antônio Olavo Cardoso; Bandeca, Matheus Coelho

2015-05-01

Repeated sterilizations cycles cause undesirable alterations in the material properties of the instruments, such as corrosion, alterations in the hardness of the metal and the loss of the cutting sharpness of the instrument. This research examined the effect of repeated dry heat sterilization and autoclaves cycles on carbon steel (CS) and stainless steel (SS) curettes during the scaling and root planning. A total of 77 Gracey curettes were used in this study. Of these, 35 were SS and 42 were CS curettes submitted in different process: Dry heat, autoclave, inhibition of corrosion and autoclave, scaling, root planning and dry heat, scaling, root planning, inhibition of corrosion and autoclave. The inhibition of corrosion used on the carbon curettes (prior to sterilization in the autoclave) was sodium nitrite at 2%. The curettes received 10 consecutive cycles of sterilization and after that the cutting edges were examined in the electronic microscope, at 60 and 100 magnification times. The images were evaluated by three independent examiners, who compared the photographs of each group with the control group. The surface corrosion products and a deterioration of the edges were observed and the results showed that the SS curettes suffered little alteration with sterilization, scaling, root planning whereas the CS curettes were visibly affected by sterilization in the autoclave, but when the inhibition of corrosion was used prior to the sterilization, the oxidation was considerably reduced.

Groundwater withdrawal impacts in a karst area

NASA Astrophysics Data System (ADS)

Destephen, R. A.; Benson, C. P.

1993-12-01

During a 3000-gpm pump test on a groundwater supply well in Augusta County, Virginia, residential properties were impacted. The impacts included lowered farm pond water levels, development of a sinkhole, and water level decrease in residential wells. A study was performed to assess whether a lower design yield was possible with minimal impacts on adjacent property. This study included a 48-h 1500-gpm pump test that evaluated impacts due to: (1) sinkhole development and potential damage to homes, (2) loss of water in residential wells, and (3) water-quality degradation. Spring flows, residential well levels, survey monuments, and water quality were monitored. Groundwater and surface water testing included inorganic water-quality parameters and microbiological parameters. The latter included particulate analyses, Giardia cysts, and coliforms, which were used to evaluate the connection between groundwater and local surface waterbodies. Although results of the study indicated a low potential for structural damage due to future sinkhole activity, it showed that the water quality of some residential wells might be degraded. Because particulate analyses confirmed that groundwater into the supply well is under the direct influence of surface water, it was recommended that certain residents be placed on an alternate water supply prior to production pumping and that filtration be provided for the well in accordance with the Surface Water Treatment Rule. A mitigation plan was implemented. This plan included crack surveys, a long-term settlement station monitoring program, and limitation of the groundwater withdrawal rate to 1.0 million gallons per day (mgd) and maximum production rate to 1500 gpm.

Mangold Property Management, Inc. Information Sheet

EPA Pesticide Factsheets

Mangold Property Management, Inc. (the Company) is located in Monterey, California. The settlement involves the lease of properties constructed prior to 1978, located in Salinas and Monterey, California.

Bone surface enhancement in ultrasound images using a new Doppler-based acquisition/processing method.

PubMed

Yang, Xu; Tang, Songyuan; Tasciotti, Ennio; Righetti, Raffaella

2018-01-17

Ultrasound (US) imaging has long been considered as a potential aid in orthopedic surgeries. US technologies are safe, portable and do not use radiations. This would make them a desirable tool for real-time assessment of fractures and to monitor fracture healing. However, image quality of US imaging methods in bone applications is limited by speckle, attenuation, shadow, multiple reflections and other imaging artifacts. While bone surfaces typically appear in US images as somewhat 'brighter' than soft tissue, they are often not easily distinguishable from the surrounding tissue. Therefore, US imaging methods aimed at segmenting bone surfaces need enhancement in image contrast prior to segmentation to improve the quality of the detected bone surface. In this paper, we present a novel acquisition/processing technique for bone surface enhancement in US images. Inspired by elastography and Doppler imaging methods, this technique takes advantage of the difference between the mechanical and acoustic properties of bones and those of soft tissues to make the bone surface more easily distinguishable in US images. The objective of this technique is to facilitate US-based bone segmentation methods and improve the accuracy of their outcomes. The newly proposed technique is tested both in in vitro and in vivo experiments. The results of these preliminary experiments suggest that the use of the proposed technique has the potential to significantly enhance the detectability of bone surfaces in noisy ultrasound images.

Bone surface enhancement in ultrasound images using a new Doppler-based acquisition/processing method

NASA Astrophysics Data System (ADS)

Yang, Xu; Tang, Songyuan; Tasciotti, Ennio; Righetti, Raffaella

2018-01-01

Ultrasound (US) imaging has long been considered as a potential aid in orthopedic surgeries. US technologies are safe, portable and do not use radiations. This would make them a desirable tool for real-time assessment of fractures and to monitor fracture healing. However, image quality of US imaging methods in bone applications is limited by speckle, attenuation, shadow, multiple reflections and other imaging artifacts. While bone surfaces typically appear in US images as somewhat ‘brighter’ than soft tissue, they are often not easily distinguishable from the surrounding tissue. Therefore, US imaging methods aimed at segmenting bone surfaces need enhancement in image contrast prior to segmentation to improve the quality of the detected bone surface. In this paper, we present a novel acquisition/processing technique for bone surface enhancement in US images. Inspired by elastography and Doppler imaging methods, this technique takes advantage of the difference between the mechanical and acoustic properties of bones and those of soft tissues to make the bone surface more easily distinguishable in US images. The objective of this technique is to facilitate US-based bone segmentation methods and improve the accuracy of their outcomes. The newly proposed technique is tested both in in vitro and in vivo experiments. The results of these preliminary experiments suggest that the use of the proposed technique has the potential to significantly enhance the detectability of bone surfaces in noisy ultrasound images.

Optimized postweld heat treatment procedures for 17-4 PH stainless steels

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

Bhaduri, A.K.; Sujith, S.; Srinivasan, G.

1995-05-01

The postweld heat treatment (PWHT) procedures for 17-4 PH stainless steel weldments of matching chemistry was optimized vis-a-vis its microstructure prior to welding based on microstructural studies and room-temperature mechanical properties. The 17-4 PH stainless steel was welded in two different prior microstructural conditions (condition A and condition H 1150) and then postweld heat treated to condition H900 or condition H1150, using different heat treatment procedures. Microstructural investigations and room-temperature tensile properties were determined to study the combined effects of prior microstructural and PWHT procedures.

The effects of clam fishing on the properties of surface sediments in the lagoon of Venice, Italy

NASA Astrophysics Data System (ADS)

Aspen, R. J.; Vardy, S.; Perkins, R. G.; Davidson, I. R.; Bates, R.; Paterson, D. M.

Harvesting of clams(Tapes philippinarum) has important socio-economic and environmental implications for the Venice lagoon area, Italy. Clam harvesting disrupts the structure of benthic communities but the effects upon sediment stability and surface structure remain unclear. The effect of clam fishing on the sediment properties of the lagoon bed was investigated at two different sites, a heavily fished site (San Angelo) and an infrequently fished site (San Giaccomo). Both sites were assessed for immediate impacts of fishing, using indicators of biogenic sediment stabilisation. Samples were taken at three points along three 100 m linear transects at each site prior to and post fishing. Paired samples were also taken parallel to each transect at a distance of 5m, to allow for temporal variation. Sediment stability, measured with a cohesive strength meter (CSM), was significantly higher at the less impacted site (F1,34 = 6.23, p < 0.018), was correlated with indicators of biogenic sediment stabilisation and decreased by approximately 50% following the trawling event. Concomitant decreases in chlorophyll a (chl a), colloidal-S carbohydrate and dry bulk density were observed on the transect after fishing but not adjacent to the fishing path. At the heavily impacted site, clam fishing by trawling had, in general, no significant effect on the biological and physical properties (although chl a did decrease significantly after fishing). The lack of a significant impact from fishing at the impacted site was attributed to the higher frequency of fishing occurring in this area. Hence, frequent fishing of the lagoon prevents establishment of biotic communities, preventing biostabilisation and thus reduces the stability of the surface sediment.

Influence of airborne-particle abrasion on mechanical properties and bond strength of carbon/epoxy and glass/bis-GMA fiber-reinforced resin posts.

PubMed

Soares, Carlos Jose; Santana, Fernanda Ribeiro; Pereira, Janaina Carla; Araujo, Tatiana Santos; Menezes, Murilo Souza

2008-06-01

Controversy exists concerning the use of fiber-reinforced posts to improve bond strength to resin cement because some precementation treatments can compromise the mechanical properties of the posts. The purpose of this study was to analyze the influence of airborne-particle abrasion on the mechanical properties and microtensile bond strength (MTBS) of carbon/epoxy and glass/bis-GMA fiber-reinforced resin posts. Flexural strength (delta(f)), flexural modulus (E(f)), and stiffness (S) were assessed using a 3-point bending test for glass fiber-reinforced and carbon fiber-reinforced resin posts submitted to airborne-particle abrasion (AB) with 50-microm Al(2)O(3), and for posts without any surface treatment (controls) (n=10). Forty glass fiber (GF) and 40 carbon fiber (CF) posts were submitted to 1 of 4 surface treatments (n=10) prior to MTBS testing: silane (S); silane and adhesive (SA); airborne-particle abrasion with 50-microm Al(2)O(3) and silane (ABS); airborne-particle abrasion, silane, and adhesive (ABSA). Two composite resin restorations (Filtek Z250) with rounded depressions in the lateral face were bilaterally fixed to the post with resin cement (RelyX ARC). Next, the specimen was sectioned with a precision saw running perpendicular to the bonded surface to obtain 10 bonded beam specimens with a cross-sectional area of 1 mm(2). Each beam specimen was tested in a mechanical testing machine (EMIC 2,000 DL), under stress, at a crosshead speed of 0.5 mm/min until failure. Data were analyzed by 2-way ANOVA followed by Tukey HSD test (alpha=.05). Failure patterns of tested specimens were analyzed using scanning electron microscopy (SEM). The 3-point bending test demonstrated significant differences among groups only for the post type factor for flexural strength, flexural modulus, and stiffness. The carbon fiber posts exhibited significantly higher mean flexural strength (P=.001), flexural modulus (P=.003), and stiffness (P=.001) values when compared with glass fiber posts, irrespective of surface treatment. An alteration in the superficial structure of the posts could be observed by SEM after airborne-particle abrasion. MTBS testing showed no significant effect for the surface treatment type; however, significant effects for post system factor and for interaction between the 2 factors were observed. For the carbon fiber post, the ABSA surface treatment resulted in values significantly lower than the S surface treatment. SEM analysis of MTBS-tested specimens demonstrated adhesive and cohesive failures. Airborne-particle abrasion did not influence the mechanical properties of the post; however, it produced undesirable surface changes, which could reduce the bond strength to resin cement. For the surface treatments studied, if silane is applied, the adhesive system and airborne-particle abrasion are not necessary.

Transformation twinning of Ni-Mn-Ga characterized with temperature-controlled atomic force microscopy.

PubMed

Reinhold, Matthew; Watson, Chad; Knowlton, William B; Müllner, Peter

2010-06-01

The magnetomechanical properties of ferromagnetic shape memory alloy Ni-Mn-Ga single crystals depend strongly on the twin microstructure, which can be modified through thermomagnetomechanical training. Atomic force microscopy (AFM) and magnetic force microscopy (MFM) were used to characterize the evolution of twin microstructures during thermomechanical training of a Ni-Mn-Ga single crystal. Experiments were performed in the martensite phase at 25 degrees C and in the austenite phase at 55 degrees C. Two distinct twinning surface reliefs were observed at room temperature. At elevated temperature (55 degrees C), the surface relief of one twinning mode disappeared while the other relief remained unchanged. When cooled back to 25 degrees C, the twin surface relief recovered. The relief persisting at elevated temperature specifies the positions of twin boundaries that were present when the sample was polished prior to surface characterization. AFM and MFM following thermomechanical treatment provide a nondestructive method to identify the crystallographic orientation of each twin and of each twin boundary plane. Temperature dependent AFM and MFM experiments reveal the twinning history thereby establishing the technique as a unique predictive tool for revealing the path of the martensitic and reverse transformations of magnetic shape memory alloys.

Transformation twinning of Ni–Mn–Ga characterized with temperature-controlled atomic force microscopy

PubMed Central

Reinhold, Matthew; Watson, Chad; Knowlton, William B.; Müllner, Peter

2010-01-01

The magnetomechanical properties of ferromagnetic shape memory alloy Ni–Mn–Ga single crystals depend strongly on the twin microstructure, which can be modified through thermomagnetomechanical training. Atomic force microscopy (AFM) and magnetic force microscopy (MFM) were used to characterize the evolution of twin microstructures during thermomechanical training of a Ni–Mn–Ga single crystal. Experiments were performed in the martensite phase at 25 °C and in the austenite phase at 55 °C. Two distinct twinning surface reliefs were observed at room temperature. At elevated temperature (55 °C), the surface relief of one twinning mode disappeared while the other relief remained unchanged. When cooled back to 25 °C, the twin surface relief recovered. The relief persisting at elevated temperature specifies the positions of twin boundaries that were present when the sample was polished prior to surface characterization. AFM and MFM following thermomechanical treatment provide a nondestructive method to identify the crystallographic orientation of each twin and of each twin boundary plane. Temperature dependent AFM and MFM experiments reveal the twinning history thereby establishing the technique as a unique predictive tool for revealing the path of the martensitic and reverse transformations of magnetic shape memory alloys. PMID:20589105

Inspecting Friction Stir Welding using Electromagnetic Probes

NASA Technical Reports Server (NTRS)

Kinchen, David G.

2004-01-01

A report describes the use of advanced electromagnetic probes to measure the dimensions, the spatial distribution of electrical conductivity, and related other properties of friction stir welds (FSWs) between parts made of the same or different aluminum alloy(s). The probes are of the type described in in another Tech Brief. To recapitulate: A probe of this type is essentially an eddy-current probe that includes a primary (driver) winding that meanders and multiple secondary (sensing) windings that meander along the primary winding. Electrical conductivity is commonly used as a measure of heat treatment and tempering of aluminum alloys, but prior to the development of these probes, the inadequate sensitivity and limited accuracy of electrical-conductivity probes precluded such use on FSWs between different aluminum alloys, and the resolution of those probes was inadequate for measurement of FSW dimensions with positions and metallurgical properties. In contrast, the present probes afford adequate accuracy and spatial resolution for the purposes of measuring the dimensions of FSW welds and correlating spatially varying electrical conductivities with metallurgical properties, including surface defects.

An investigation of the moisture sorption and permeability properties of mill-fabricated oriented strandboard

NASA Astrophysics Data System (ADS)

Timusk, Paul Christopher

This thesis brings the disciplines of Building Science and Wood Science together in the study of the moisture-related properties of oriented strand board (OSB). Using controlled mill-manufactured panels specifically made for this project, this research reveals how the sorption and permeance properties of OSB are affected by several variables including production parameters and physical panel properties, moisture-history, and relative humidity exposure. Since OSB varies in composition through its thickness, this study isolated and tested various core and surface components. Permeability and sorption properties of individual OSB layers, intact panel sections, and panel sections that had undergone cyclic wetting and drying or relative humidity cycling prior to testing, were evaluated. After laboratory testing and analysis, a set of OSB permeance and sorption values were entered into the material database of a finite-element hygrothermal computer modeling program. Relying on this data, a series of hygrothermal wall simulations were carried out using standard wall sections exposed to various climate conditions found throughout North America. These simulations revealed that the results vary widely depending upon the permeance and sorption values used. Thus the common practice of characterizing a range of OSB products with various moisture histories by using a single permeance or sorption value may not be wise.

Surface Sampling of Spores in Dry-Deposition Aerosols▿

PubMed Central

Edmonds, Jason M.; Collett, Patricia J.; Valdes, Erica R.; Skowronski, Evan W.; Pellar, Gregory J.; Emanuel, Peter A.

2009-01-01

The ability to reliably and reproducibly sample surfaces contaminated with a biological agent is a critical step in measuring the extent of contamination and determining if decontamination steps have been successful. The recovery operations following the 2001 attacks with Bacillus anthracis spores were complicated by the fact that no standard sample collection format or decontamination procedures were established. Recovery efficiencies traditionally have been calculated based upon biological agents which were applied to test surfaces in a liquid format and then allowed to dry prior to sampling tests, which may not be best suited for a real-world event with aerosolized biological agents. In order to ascertain if differences existed between air-dried liquid deposition and biological spores which were allowed to settle on a surface in a dried format, a study was undertaken to determine if differences existed in surface sampling recovery efficiencies for four representative surfaces. Studies were then undertaken to compare sampling efficiencies between liquid spore deposition and aerosolized spores which were allowed to gradually settle under gravity on four different test coupon types. Tests with both types of deposition compared efficiencies of four unique swabbing materials applied to four surfaces with various surface properties. Our studies demonstrate that recovery of liquid-deposited spores differs significantly from recovery of dry aerosol-deposited spores in most instances. Whether the recovery of liquid-deposited spores is overexaggerated or underrepresented with respect to that of aerosol-deposited spores depends upon the surface material being tested. PMID:18997021

30 CFR 872.31 - Are there any restrictions on how you may use prior balance replacement funds?

Code of Federal Regulations, 2010 CFR

2010-07-01

... prior balance replacement funds? 872.31 Section 872.31 Mineral Resources OFFICE OF SURFACE MINING... ELIGIBLE STATES AND INDIAN TRIBES § 872.31 Are there any restrictions on how you may use prior balance replacement funds? (a) Yes. If you are certified under section 411(a) of SMCRA, you may only use prior balance...

30 CFR 872.31 - Are there any restrictions on how you may use prior balance replacement funds?

Code of Federal Regulations, 2011 CFR

2011-07-01

... prior balance replacement funds? 872.31 Section 872.31 Mineral Resources OFFICE OF SURFACE MINING... ELIGIBLE STATES AND INDIAN TRIBES § 872.31 Are there any restrictions on how you may use prior balance replacement funds? (a) Yes. If you are certified under section 411(a) of SMCRA, you may only use prior balance...

Heat treatment versus properties studies associated with the Inconel 718 PBF acoustic filters

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

Smolik, G.R.; Reuter, W.G.

PBF acoustic filter Unit No. 1 cracked when heat treatment was attempted. The effects of prior thermal cycling, solution anneal temperature, and cooling rate from solution anneals were investigated. The investigations concerned influences of the above variables upon both 1400$sup 0$F stress rupture solution- annealed properties and room temperature age-hardened properties. 1400$sup 0$F stress rupture properties were of interest to assist the prevention of cracking during heat treatments. Room temperature age-hardened properties were needed to ensure that design requirement would be provided. Prior thermal cycling was investigated to determine if extra thermal cycles would be detrimental to the repaired filter.more » Slow furnace cools were considered as a means of reducing thermal stresses. Effects of solution annealing at 2000 and 1900$sup 0$F were also determined. Test results showed that slow cooling rates would not only reduce thermal stresses but also improve 1400$sup 0$F ductility. A modified aging treatment was established which provided the required 145 ksi room temperature yield strength for the slowly cooled material. Prior cooling did not degrade final age-hardened room temperature tensile or impact properties. (auth)« less

Effects of macro- versus nanoporous silicon substrates on human aortic endothelial cell behavior

PubMed Central

2014-01-01

Human aortic endothelial cells play a key role in the pathogenesis of atherosclerosis, which is a common, progressive, and multifactorial disease that is the clinical endpoint of an inflammatory process and endothelial dysfunction. Study and development of new therapies against cardiovascular disease must be tested in vitro cell models, prior to be evaluated in vivo. To this aim, new cell culture platforms are developed that allow cells to grow and respond to their environment in a realistic manner. In this work, the cell adhesion and morphology of endothelial cells are investigated on functionalized porous silicon substrates with two different pore size configurations: macroporous and nanoporous silicon. Herein, we modified the surfaces of porous silicon substrates by aminopropyl triethoxysilane, and we studied how different pore geometries induced different cellular response in the cell morphology and adhesion. The cell growth over the surface of porous silicon becomes an attractive field, especially for medical applications. Surface properties of the biomaterial are associated with cell adhesion and as well as, with proliferation, migration and differentiation. PMID:25246859

Interfacial B-site atomic configuration in polar (111) and non-polar (001) SrIrO3/SrTiO3 heterostructures

NASA Astrophysics Data System (ADS)

Anderson, T. J.; Zhou, H.; Xie, L.; Podkaminer, J. P.; Patzner, J. J.; Ryu, S.; Pan, X. Q.; Eom, C. B.

2017-09-01

The precise control of interfacial atomic arrangement in ABO3 perovskite heterostructures is paramount, particularly in cases where the subsequent electronic properties of the material exhibit geometrical preferences along polar crystallographic directions that feature inevitably complex surface reconstructions. Here, we present the B-site interfacial structure in polar (111) and non-polar (001) SrIrO3/SrTiO3 interfaces. The heterostructures were examined using scanning transmission electron microscopy and synchrotron-based coherent Bragg rod analysis. Our results reveal the preference of B-site intermixing across the (111) interface due to the polarity-compensated SrTiO3 substrate surface prior to growth. By comparison, the intermixing at the non-polar (001) interface is negligible. This finding suggests that the intermixing may be necessary to mitigate epitaxy along heavily reconstructed and non-stoichiometric (111) perovskite surfaces. Furthermore, this preferential B-site configuration could allow the geometric design of the interfacial perovskite structure and chemistry to selectively engineer the correlated electronic states of the B-site d-orbital.

Nucleation and growth of microdroplets of ionic liquids deposited by physical vapor method onto different surfaces

NASA Astrophysics Data System (ADS)

Costa, José C. S.; Coelho, Ana F. S. M. G.; Mendes, Adélio; Santos, Luís M. N. B. F.

2018-01-01

Nanoscience and technology has generated an important area of research in the field of properties and functionality of ionic liquids (ILs) based materials and their thin films. This work explores the deposition process of ILs droplets as precursors for the fabrication of thin films, by means of physical vapor deposition (PVD). It was found that the deposition (by PVD on glass, indium tin oxide, graphene/nickel and gold-coated quartz crystal surfaces) of imidazolium [C4mim][NTf2] and pyrrolidinium [C4C1Pyrr][NTf2] based ILs generates micro/nanodroplets with a shape, size distribution and surface coverage that could be controlled by the evaporation flow rate and deposition time. No indication of the formation of a wetting-layer prior to the island growth was found. Based on the time-dependent morphological analysis of the micro/nanodroplets, a simple model for the description of the nucleation process and growth of ILs droplets is presented. The proposed model is based on three main steps: minimum free area to promote nucleation; first order coalescence; second order coalescence.

Deformation and fracture of aluminum-lithium alloys: The effect of dissolved hydrogen

NASA Technical Reports Server (NTRS)

Rivet, F. C.; Swanson, R. E.

1990-01-01

The effects of dissolved hydrogen on the mechanical properties of 2090 and 2219 alloys are studied. The work done during this semi-annual period consists of the hydrogen charging study and some preliminary mechanical tests. Prior to SIMS analysis, several potentiostatic and galvanostatic experiments were performed for various times (going from 10 minutes to several hours) in the cathodic zone, and for the two aqueous solutions: 0.04N of HCl and 0.1N NaOH both combined with a small amount of As2O3. A study of the surface damage was conducted in parallel with the charging experiments. Those tests were performed to choose the best charging conditions without surface damage. Disk rupture tests and tensile tests are part of the study designed to investigate the effect of temperature, surface roughness, strain rate, and environment on the fracture behavior. The importance of the roughness and environment were shown using the disk rupture test as well as the importance of the strain rate under hydrogen environment. The tensile tests, without hydrogen effects, have not shown significant differences between low and room temperature.

JH & JH Properties, LLC Information Sheet

EPA Pesticide Factsheets

JH & JH Properties, LLC (the Company) is located in Fargo, North Dakota. The settlement involves renovation activities conducted at a property constructed prior to 1978, located in Fargo, North Dakota.

Interface Trap Density Reduction for Al2O3/GaN (0001) Interfaces by Oxidizing Surface Preparation prior to Atomic Layer Deposition.

PubMed

Zhernokletov, Dmitry M; Negara, Muhammad A; Long, Rathnait D; Aloni, Shaul; Nordlund, Dennis; McIntyre, Paul C

2015-06-17

We correlate interfacial defect state densities with the chemical composition of the Al2O3/GaN interface in metal-oxide-semiconductor (MOS) structures using synchrotron photoelectron emission spectroscopy (PES), cathodoluminescence and high-temperature capacitance-voltage measurements. The influence of the wet chemical pretreatments involving (1) HCl+HF etching or (2) NH4OH(aq) exposure prior to atomic layer deposition (ALD) of Al2O3 were investigated on n-type GaN (0001) substrates. Prior to ALD, PES analysis of the NH4OH(aq) treated surface shows a greater Ga2O3 component compared to either HCl+HF treated or as-received surfaces. The lowest surface concentration of oxygen species is detected on the acid etched surface, whereas the NH4OH treated sample reveals the lowest carbon surface concentration. Both surface pretreatments improve electrical characteristics of MOS capacitors compared to untreated samples by reducing the Al2O3/GaN interface state density. The lowest interfacial trap density at energies in the upper band gap is detected for samples pretreated with NH4OH. These results are consistent with cathodoluminescence data indicating that the NH4OH treated samples show the strongest band edge emission compared to as-received and acid etched samples. PES results indicate that the combination of reduced carbon contamination while maintaining a Ga2O3 interfacial layer by NH4OH(aq) exposure prior to ALD results in fewer interface traps after Al2O3 deposition on the GaN substrate.

Osteoblast adhesion, migration, and proliferation variations on chemically patterned nanocrystalline diamond films evaluated by live-cell imaging.

PubMed

Broz, Antonin; Ukraintsev, Egor; Kromka, Alexander; Rezek, Bohuslav; Hubalek Kalbacova, Marie

2017-05-01

Cell fate modulation by adapting the surface of a biocompatible material is nowadays a challenge in implantology, tissue engineering as well as in construction of biosensors. Nanocrystalline diamond (NCD) thin films are considered promising in these fields due to their extraordinary physical and chemical properties and diverse ways in which they can be modified structurally and chemically. The initial cell distribution, the rate of cell adhesion, distance of cell migration and also the cell proliferation are influenced by the NCD surface termination. Here, we use real-time live-cell imaging to investigate the above-mentioned processes on oxidized NCD (NCD-O) and hydrogenated NCD (NCD-H) to elucidate cell preference to the NCD-O especially on surfaces with microscopic surface termination patterns. Cells adhere more slowly and migrate farther on NCD-H than on NCD-O. Cells seeded with a fetal bovine serum (FBS) supplement in the medium move across the surface prior to adhesion. In the absence of FBS, the cells adhere immediately, but still exhibit different migration and proliferation on NCD-O/H regions. We discuss the impact of these effects on the formation of cell arrays on micropatterned NCD. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1469-1478, 2017. © 2017 Wiley Periodicals, Inc.

Oriented and covalent immobilization of target molecules to solid supports: synthesis and application of a light-activatable and thiol-reactive cross-linking reagent.

PubMed

Collioud, A; Clémence, J F; Sänger, M; Sigrist, H

1993-01-01

Light-dependent oriented and covalent immobilization of target molecules has been achieved by combining two modification procedures: light-dependent coupling of target molecules to inert surfaces and thiol-selective reactions occurring at macromolecule or substrate surfaces. For immobilization purposes the heterobifunctional reagent N-[m-[3-(trifluoromethyl)diazirin-3-yl]phenyl]-4-maleimidobutyr amide was synthesized and chemically characterized. The photosensitivity of the carbene-generating reagent and its reactivity toward thiols were ascertained. Light-induced cross-linking properties of the reagent were documented (i) by reacting first the maleimide function with a thiolated surface, followed by carbene insertion into applied target molecules, (ii) by photochemical coupling of the reagent to an inert support followed by thermochemical reactions with thiol functions, and (iii) by thermochemical modification of target molecules prior to carbene-mediated insertion into surface materials. Procedures mentioned led to light-dependent covalent immobilization of target molecules including amino acids, a synthetic peptide, and antibody-derived F(ab') fragments. Topically selective, light-dependent immobilization was attained with the bifunctional reagent by irradiation of coated surfaces through patterned masks. Glass and polystyrene served as substrates. Molecular orientation is asserted by inherently available or selectively introduced terminal thiol functions in F(ab') fragments and synthetic polypeptides, respectively.

An atomic scale study of surface termination and digital alloy growth in InGaAs/AlAsSb multi-quantum wells.

PubMed

Mauger, S J C; Bozkurt, M; Koenraad, P M; Zhao, Y; Folliot, H; Bertru, N

2016-07-20

An atomic scale study has been performed to understand the influence of the (As,Sb) shutter sequences during interface formation on the optical properties of InGaAs/AlAsSb quantum wells. Our cross-sectional scanning tunneling microscopy results show that the onset of the Sb profile is steep in the Sb-containing layers whereas an appreciable segregation of Sb in the subsequently grown Sb free layers is observed. The steep rise of the Sb profile is due to extra Sb that is supplied to the surface prior to the growth of the Sb-containing layers. No relation is found between the (As,Sb) termination conditions of the Sb-containing layers and the resulting Sb profiles in the capping layers. Correspondingly we see that the optical properties of these quantum wells are also nearly independent on the (As,Sb) shutter sequences at the interface. Digital alloy growth in comparison to conventional molecular beam epitaxy growth was also explored. X-ray results suggest that the structural properties of the quantum well structures grown by conventional molecular beam epitaxy techniques are slightly better than those formed by digital alloy growth. However photoluminescence studies indicate that the digital alloy samples give rise to a more intense and broader photoluminescence emission. Cross-sectional scanning tunneling microscopy measurements reveal that lateral composition modulations present in the digital alloys are responsible for the enhancement of the photoluminescence intensity and inhomogeneous broadening.

30 CFR 77.1712 - Reopening mines; notification; inspection prior to mining.

Code of Federal Regulations, 2010 CFR

2010-07-01

... to mining. 77.1712 Section 77.1712 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... prior to mining. Prior to reopening any surface coal mine after it has been abandoned or declared... an authorized representative of the Secretary before any mining operations in such mine are...

30 CFR 77.1712 - Reopening mines; notification; inspection prior to mining.

Code of Federal Regulations, 2011 CFR

2011-07-01

... to mining. 77.1712 Section 77.1712 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... prior to mining. Prior to reopening any surface coal mine after it has been abandoned or declared... an authorized representative of the Secretary before any mining operations in such mine are...

The Aerostructures Test Wing (ATW) experiment, which consisted of an 18-inch carbon fiber test wing with surface-mounted piezoelectric strain actuators, undergoing ground testing prior to flight on Dryden's F-15B Research Testbed aircraft

NASA Image and Video Library

2001-03-28

The Aerostructures Test Wing (ATW) experiment, which consisted of an 18-inch carbon fiber test wing with surface-mounted piezoelectric strain actuators, undergoing ground testing prior to flight on Dryden's F-15B Research Testbed aircraft

Micro-rheology and interparticle interactions in aerosols probed with optical tweezers

NASA Astrophysics Data System (ADS)

Reid, Jonathan P.; Power, Rory M.; Cai, Chen; Simpson, Stephen H.

2014-09-01

Using optical tweezers for micro-rheological investigations of a surrounding fluid has been routinely demonstrated. In this work, we will demonstrate that rheological measurements of the bulk and surface properties of aerosol particles can be made directly using optical tweezers, providing important insights into the phase behavior of materials in confined environments and the rate of molecular diffusion in viscous phases. The use of holographic optical tweezers to manipulate aerosol particles has become standard practice in recent years, providing an invaluable tool to investigate particle dynamics, including evaporation/ condensation kinetics, chemical aging and phase transformation. When combined with non-linear Raman spectroscopy, the size and refractive index of a particle can be determined with unprecedented accuracy <+/- 0.05%). Active control of the relative positions of pairs of particles can allow studies of the coalescence of particles, providing a unique opportunity to investigate the bulk and surface properties that govern the hydrodynamic relaxation in particle shape. In particular, we will show how the viscosity and surface tension of particles can be measured directly in the under-damped regime at low viscosity. In the over-damped regime, we will show that viscosity measurements can extend close to the glass transition, allowing measurements over an impressive dynamic range of 12 orders of magnitude in relaxation timescale and viscosity. Indeed, prior to the coalescence event, we will show how the Brownian trajectories of trapped particles can yield important and unique insights into the interactions of aerosol particles.

26 CFR 1.9005-1 - Election relating to the determination of gross income from the property for taxable years...

Code of Federal Regulations, 2010 CFR

2010-04-01

... income from the property for taxable years beginning prior to 1961 in the case of clay and quartzite used... beginning prior to 1961 in the case of clay and quartzite used in making refractory products. (a) In general... provisions of the Internal Revenue Code of 1939) in the case of quartzite and clay used by the mine owner or...

Size- and shape-dependent surface thermodynamic properties of nanocrystals

NASA Astrophysics Data System (ADS)

Fu, Qingshan; Xue, Yongqiang; Cui, Zixiang

2018-05-01

As the fundamental properties, the surface thermodynamic properties of nanocrystals play a key role in the physical and chemical changes. However, it remains ambiguous about the quantitative influence regularities of size and shape on the surface thermodynamic properties of nanocrystals. Thus by introducing interface variables into the Gibbs energy and combining Young-Laplace equation, relations between the surface thermodynamic properties (surface Gibbs energy, surface enthalpy, surface entropy, surface energy and surface heat capacity), respectively, and size of nanocrystals with different shapes were derived. Theoretical estimations of the orders of the surface thermodynamic properties of nanocrystals agree with available experimental values. Calculated results of the surface thermodynamic properties of Au, Bi and Al nanocrystals suggest that when r > 10 nm, the surface thermodynamic properties linearly vary with the reciprocal of particle size, and when r < 10 nm, the effect of particle size on the surface thermodynamic properties becomes greater and deviates from linear variation. For nanocrystals with identical equivalent diameter, the more the shape deviates from sphere, the larger the surface thermodynamic properties (absolute value) are.

32 CFR 564.58 - Determination of amount allowable.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the property immediately prior to the accident or incident. Subject to the foregoing, the amount... to the condition in which it was immediately prior to the accident or incident. However, if as the... less than that prior to the accident or incident, the difference in value will be added to the cost of...

32 CFR 564.58 - Determination of amount allowable.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the property immediately prior to the accident or incident. Subject to the foregoing, the amount... to the condition in which it was immediately prior to the accident or incident. However, if as the... less than that prior to the accident or incident, the difference in value will be added to the cost of...

A novel approach for application of nylon membranes in the biosensing domain

NASA Astrophysics Data System (ADS)

Farahmand, Elham; Ibrahim, Fatimah; Hosseini, Samira; Rothan, Hussin A.; Yusof, Rohana; Koole, Leo H.; Djordjevic, Ivan

2015-10-01

In this paper we report the polymer-coated microporous nylon membranes and their application as platforms for protein immobilization and subsequent detection of the dengue virus (DV) in blood serum. Protein recognition experiments were performed with enzyme-linked immunosorbent assay (ELISA). The polymers used for coatings were synthesized by free-radical polymerization reaction between methyl methacrylate (MMA) and methacrylic acid (MAA) in different concentrations. The MAA monomer has carefully been chosen to generate polymers with pendant carboxyl (-COOH) groups, which also exist on polymer surfaces. A high degree of control over surface-exposed -COOH groups has been achieved through variation of monomers concentration in polymerization reaction. The general aspect of this work relies on the dengue antibody (Ab) immobilization on surface -COOH groups via physical attachment or covalent immobilization. Prior to Ab immobilization and ELISA experiment, polymer-coated nylon samples were analyzed in detail for their physical properties by atomic force microscopy (AFM), scanning electron microscopy (SEM), and water-in-air contact angle (WCA) measurements. Membranes were further analyzed by Fourier transform infrared spectroscopy (FTIR) in order to establish the relationship between wettability, porosity, and surface roughness with chemical composition and concentration of -COOH groups on the coating's surface. Optimized coatings have shown high sensitivity towards dengue Ab molecules, revealing fundamental aspect of polymer-protein interfaces as a function of surface -COOH groups' concentration.

Pre-treatment of multi-walled carbon nanotubes for polyetherimide mixed matrix hollow fiber membranes.

PubMed

Goh, P S; Ng, B C; Ismail, A F; Aziz, M; Hayashi, Y

2012-11-15

Mixed matrix hollow fibers composed of multi-walled carbon nanotubes (MWCNTs) and polyetherimide (PEI) were fabricated. Pre-treatment of MWCNTs was carried out prior to the incorporation into the polymer matrix using a simple and feasible two stages approach that involved dry air oxidation and surfactant dispersion. The characterizations of the surface treated MWCNTs using TEM and Raman spectroscopy have evidenced the effectiveness of dry air oxidation in eliminating undesired amorphous carbon and metal catalyst while surfactant dispersion using Triton X100 has suppressed the agglomeration of MWCNTs. The resultant mixed matrix hollow fibers were applied for O(2)/N(2) pure gas separation. Interestingly, it was found that removal of disordered amorphous carbons and metal particles has allowed the hollow structures to be more accessible for the fast and smooth transport of gas molecules, hence resulted in noticeable improvement in the gas separation properties. The composite hollow fibers embedded with the surface modified MWCNTs showed increase in permeability as much as 60% while maintaining the selectivity of the O(2)/N(2) gas pair. This study highlights the necessity to establish an appropriate pre-treatment approach for MWCNTs in order to fully utilize the beneficial transport properties of this material in mixed matrix polymer nanocomposite for gas separation. Copyright © 2012 Elsevier Inc. All rights reserved.

Structural, Electrical and Optical Properties of Sputtered-Grown InN Films on ZnO Buffered Silicon, Bulk GaN, Quartz and Sapphire Substrates

NASA Astrophysics Data System (ADS)

Bashir, Umar; Hassan, Zainuriah; Ahmed, Naser M.; Afzal, Naveed

2018-05-01

Indium nitride (InN) films were grown on Si (111), bulk GaN, quartz and sapphire substrates by radio frequency magnetron sputtering. Prior to the film deposition, a zinc oxide (ZnO) buffer layer was deposited on all the substrates. The x-ray diffraction patterns of InN films on ZnO-buffered substrates indicated c-plane-oriented films whereas the Raman spectroscopy results indicated A1 (LO) and E2 (high) modes of InN on all the substrates. The crystalline quality of InN was found to be better on sapphire and quartz than on the other substrates. The surface roughness of InN was studied using an atomic force microscope. The results indicated higher surface roughness of the film on sapphire as compared to the others; however, roughness of the film was lower than 8 nm on all the substrates. The electrical properties indicated higher electron mobility of InN (20.20 cm2/Vs) on bulk GaN than on the other substrates. The optical band gap of InN film was more than 2 eV in all the cases and was attributed to high carrier concentration in the film.

41 CFR 102-75.1025 - When can a Federal agency abandon or destroy improvements on land or related personal property in...

Code of Federal Regulations, 2010 CFR

2010-07-01

... Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION REAL PROPERTY 75-REAL PROPERTY... time prior to actually abandoning or destroying the property, the Federal agency must donate it. ...

Nucleation and arrest of slow slip earthquakes: mechanisms and nonlinear simulations using realistic fault geometries and heterogeneous medium properties

NASA Astrophysics Data System (ADS)

Alves da Silva Junior, J.; Frank, W.; Campillo, M.; Juanes, R.

2017-12-01

Current models for slow slip earthquakes (SSE) assume a simplified fault embedded on a homogeneous half-space. In these models SSE events nucleate on the transition from velocity strengthening (VS) to velocity weakening (VW) down dip from the trench and propagate towards the base of the seismogenic zone, where high normal effective stress is assumed to arrest slip. Here, we investigate SSE nucleation and arrest using quasi-static finite element simulations, with rate and state friction, on a domain with heterogeneous properties and realistic fault geometry. We use the fault geometry of the Guerrero Gap in the Cocos subduction zone, where SSE events occurs every 4 years, as a proxy for subduction zone. Our model is calibrated using surface displacements from GPS observations. We apply boundary conditions according to the plate convergence rate and impose a depth-dependent pore pressure on the fault. Our simulations indicate that the fault geometry and elastic properties of the medium play a key role in the arrest of SSE events at the base of the seismogenic zone. SSE arrest occurs due to aseismic deformations of the domain that result in areas with elevated effective stress. SSE nucleation occurs in the transition from VS to VW and propagates as a crack-like expansion with increased nucleation length prior to dynamic instability. Our simulations encompassing multiple seismic cycles indicate SSE interval times between 1 and 10 years and, importantly, a systematic increase of rupture area prior to dynamic instability, followed by a hiatus in the SSE occurrence. We hypothesize that these SSE characteristics, if confirmed by GPS observations in different subduction zones, can add to the understanding of nucleation of large earthquakes in the seismogenic zone.

Hygroscopic properties and cloud condensation nuclei activation of limonene-derived organosulfates and their mixtures with ammonium sulfate

NASA Astrophysics Data System (ADS)

Hansen, A. M. K.; Hong, J.; Raatikainen, T.; Kristensen, K.; Ylisirniö, A.; Virtanen, A.; Petäjä, T.; Glasius, M.; Prisle, N. L.

2015-06-01

Even though organosulfates have been observed as constituents of atmospheric aerosols in a wide range of environments spanning from the subtropics to the high Arctic, their hygroscopic properties have not been investigated prior to this study. Here, limonene-derived organosulfates with a molecular weight of 250 Da (L-OS 250) were synthesized and used for simultaneous measurements with a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) and a Cloud Condensation Nuclei Counter (CCNC) to determine the hygroscopicity parameter, κ, for pure L-OS 250 and mixtures of L-OS 250 with ammonium sulfate (AS) over a wide range of humidity conditions. The κ values derived from measurements with H-TDMA decreased with increasing particle dry size for all chemical compositions investigated, indicating size dependency and/or surface effects. For pure L-OS 250, κ was found to increase with increasing relative humidity, indicating dilution/solubility effects to be significant. Discrepancies in κ between the sub- and supersaturated measurements were observed for L-OS 250, whereas κ of AS and mixed L-OS 250/AS were similar. This discrepancy was primarily ascribed to limited dissolution of L-OS 250 at subsaturated conditions. In general, hygroscopic growth factor, critical activation diameter and κ for the mixed L-OS 250/AS particles converged towards the values of pure AS for mixtures with ≥ 20 % w/w AS. Surface tension measurements of bulk aqueous L-OS 250/AS solutions showed that L-OS 250 was indeed surface active, as expected from its molecular structure, decreasing the surface tension of solutions with 24 % from the pure water-value at a L-OS 250 concentration of 0.0025 mol L-1. Based on these surface tension measurements, we present the first concentration-dependent parametrisation of surface tension for aqueous L-OS 250, which was implemented to different process-level models of L-OS 250 hygroscopicity and CCN activation. The values of κ obtained from the measurements were compared with κ calculated applying the volume additive Zdanovskii-Stokes-Robinson mixing rule, as well as κ modelled from equilibrium Köhler theory with different assumptions regarding L-OS 250 bulk-to-surface partitioning and aqueous droplet surface tension. This study is to our knowledge the first to investigate the hygroscopic properties and surface activity of L-OS 250; hence it is an important first step towards understanding the atmospheric impact of organosulfates.

Deconvoluting the Friction Stir Weld Process for Optimizing Welds

NASA Technical Reports Server (NTRS)

Schneider, Judy; Nunes, Arthur C.

2008-01-01

In the friction stir welding process, the rotating surfaces of the pin and shoulder contact the weld metal and force a rotational flow within the weld metal. Heat, generated by the metal deformation as well as frictional slippage with the contact surface, softens the metal and makes it easier to deform. As in any thermo-mechanical processing of metal, the flow conditions are critical to the quality of the weld. For example, extrusion of metal from under the shoulder of an excessively hot weld may relax local pressure and result in wormhole defects. The trace of the weld joint in the wake of the weld may vary geometrically depending upon the flow streamlines around the tool with some geometry more vulnerable to loss of strength from joint contamination than others. The material flow path around the tool cannot be seen in real time during the weld. By using analytical "tools" based upon the principles of mathematics and physics, a weld model can be created to compute features that can be observed. By comparing the computed observations with actual data, the weld model can be validated or adjusted to get better agreement. Inputs to the model to predict weld structures and properties include: hot working properties ofthe metal, pin tool geometry, travel rate, rotation and plunge force. Since metals record their prior hot working history, the hot working conditions imparted during FSW can be quantified by interpreting the final microstructure. Variations in texture and grain size result from variations in the strain accommodated at a given strain rate and temperature. Microstructural data from a variety of FSWs has been correlated with prior marker studies to contribute to our understanding of the FSW process. Once this stage is reached, the weld modeling process can save significant development costs by reducing costly trial-and-error approaches to obtaining quality welds.

Joint inversion of geophysical data using petrophysical clustering and facies deformation wth the level set technique

NASA Astrophysics Data System (ADS)

Revil, A.

2015-12-01

Geological expertise and petrophysical relationships can be brought together to provide prior information while inverting multiple geophysical datasets. The merging of such information can result in more realistic solution in the distribution of the model parameters, reducing ipse facto the non-uniqueness of the inverse problem. We consider two level of heterogeneities: facies, described by facies boundaries and heteroegenities inside each facies determined by a correlogram. In this presentation, we pose the geophysical inverse problem in terms of Gaussian random fields with mean functions controlled by petrophysical relationships and covariance functions controlled by a prior geological cross-section, including the definition of spatial boundaries for the geological facies. The petrophysical relationship problem is formulated as a regression problem upon each facies. The inversion of the geophysical data is performed in a Bayesian framework. We demonstrate the usefulness of this strategy using a first synthetic case for which we perform a joint inversion of gravity and galvanometric resistivity data with the stations located at the ground surface. The joint inversion is used to recover the density and resistivity distributions of the subsurface. In a second step, we consider the possibility that the facies boundaries are deformable and their shapes are inverted as well. We use the level set approach to perform such deformation preserving prior topological properties of the facies throughout the inversion. With the help of prior facies petrophysical relationships and topological characteristic of each facies, we make posterior inference about multiple geophysical tomograms based on their corresponding geophysical data misfits. The method is applied to a second synthetic case showing that we can recover the heterogeneities inside the facies, the mean values for the petrophysical properties, and, to some extent, the facies boundaries using the 2D joint inversion of gravity and galvanometric resistivity data. For this 2D synthetic example, we note that the position of the facies are well-recovered except far from the ground surfce where the sensitivity is too low. The figure shows the evolution of the shape of the facies during the inversion itertion by iteration.

23 CFR 710.505 - Real property donations.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 23 Highways 1 2010-04-01 2010-04-01 false Real property donations. 710.505 Section 710.505...-WAY AND REAL ESTATE Property Acquisition Alternatives § 710.505 Real property donations. (a) Donations..., whichever is greater. All donations of property received prior to the approval of the NEPA document must...

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

Oyola-Reynoso, S.; Tevis, I. D.; Chen, J.

Here, chemical grafting has been widely used to modify the surface properties of materials, especially surface energy for controlled wetting, because of the resilience of such coatings/modifications. Reagents with multiple reactive sites have been used with the expectation that a monolayer will form. The step-growth polymerization mechanism, however, suggests the possibility of gel formation for hydrolyzable moieties in the presence of physisorbed water. In this report, we demonstrated that using alkyltrichlorosilanes (trivalent [i.e., 3 reactive sites]) in the surface modification of a cellulosic material (paper) does not yield a monolayer but rather gives surface-bound particles. We infer that the presencemore » of physisorbed (surface-bound) water allows for polymerization (or oligomerization) of the silane prior to its attachment on the surface. Surface energy mismatch between the hydrophobic tails of the growing polymer and any unreacted bound water leads to the assembly of the polymerizing material into spherical particles to minimize surface tension. By varying paper grammage (16.2–201.4 g m –2), we varied the accessible surface area and thus the amount of surface-adsorbed water, allowing us to control the ratio of the silane to the bound water. Using this approach, polymeric particles were formed on the surface of cellulose fibers ranging from ~70 nm to a film. The hydrophobicity of the surface, as determined by water contact angles, correlates with particle sizes (p < 0.001, Student's t-test), and, hence, the hydrophobicity can be tuned (contact angle between 94° and 149°). Using a model structure of a house, we demonstrated that as a result of this modification, paper-based houses can be rendered self-cleaning or tolerant to surface running water. In another application, we demonstrated that the felicitous choice of architectural design allows for the hydrophobic paper to be used for water harvesting.« less

Engineering tunable bio-inspired polymeric coatings for amphiphobic fibrous materials

NASA Astrophysics Data System (ADS)

Oyola-Reynoso, Stephanie

Chemical grafting has been widely used to modify the surface properties of materials, especially surface energy for controlled wetting, because of the resilience of such coatings/modifications. Reagents with multiple reactive sites have been used with the expectation that a monolayer will form. The step-growth polymerization mechanism, however, suggests the possibility of gel formation for hydrolysable moieties in the presence of physisorbed water. In the following chapters, we demonstrate that using alkyltrichlorosilanes (trivalent [3 reactive sites]) in the surface modification of a cellulosic material (paper) does not yield a monolayer but rather gives surface-bound polymeric particles. We infer that the presence of physisorbed (surface-bound) water allows for polymerization (or oligomerization) of the silane, prior to its attachment on the surface. Surface energy mismatch between the hydrophobic tails of the growing polymer and any unreacted bound water leads to the assembly of the polymerizing material into spherical particles to minimize surface tension. By varying paper grammage (16.2-201.4 g/m2), we varied the accessible surface area and thus the amount of surface-adsorbed water, allowing us to control the ratio of the silane to the bound water. Using this approach, polymeric particles were formed on the surface of cellulose fibers ranging from 70 nm to a film. The hydrophobicity of the surface, as determined by water contact angles, correlates with particle sizes (p < 0.001, Student t-test), and, hence, the hydrophobicity can be tuned (contact angle between 94° and 149°). Using a model structure of a house, we demonstrated that as a result of this modification, cardboard houses can be rendered self-cleaning or tolerant to surface running water. Each of the chapters below supports the mechanism via a series of applications, material characterization, and/or, smart engineering.

Applying a Bayesian Approach to Identification of Orthotropic Elastic Constants from Full Field Displacement Measurements

NASA Astrophysics Data System (ADS)

Gogu, C.; Yin, W.; Haftka, R.; Ifju, P.; Molimard, J.; Le Riche, R.; Vautrin, A.

2010-06-01

A major challenge in the identification of material properties is handling different sources of uncertainty in the experiment and the modelling of the experiment for estimating the resulting uncertainty in the identified properties. Numerous improvements in identification methods have provided increasingly accurate estimates of various material properties. However, characterizing the uncertainty in the identified properties is still relatively crude. Different material properties obtained from a single test are not obtained with the same confidence. Typically the highest uncertainty is associated with respect to properties to which the experiment is the most insensitive. In addition, the uncertainty in different properties can be strongly correlated, so that obtaining only variance estimates may be misleading. A possible approach for handling the different sources of uncertainty and estimating the uncertainty in the identified properties is the Bayesian method. This method was introduced in the late 1970s in the context of identification [1] and has been applied since to different problems, notably identification of elastic constants from plate vibration experiments [2]-[4]. The applications of the method to these classical pointwise tests involved only a small number of measurements (typically ten natural frequencies in the previously cited vibration test) which facilitated the application of the Bayesian approach. For identifying elastic constants, full field strain or displacement measurements provide a high number of measured quantities (one measurement per image pixel) and hence a promise of smaller uncertainties in the properties. However, the high number of measurements represents also a major computational challenge in applying the Bayesian approach to full field measurements. To address this challenge we propose an approach based on the proper orthogonal decomposition (POD) of the full fields in order to drastically reduce their dimensionality. POD is based on projecting the full field images on a modal basis, constructed from sample simulations, and which can account for the variations of the full field as the elastic constants and other parameters of interest are varied. The fidelity of the decomposition depends on the number of basis vectors used. Typically even complex fields can be accurately represented with no more than a few dozen modes and for our problem we showed that only four or five modes are sufficient [5]. To further reduce the computational cost of the Bayesian approach we use response surface approximations of the POD coefficients of the fields. We show that 3rd degree polynomial response surface approximations provide a satisfying accuracy. The combination of POD decomposition and response surface methodology allows to bring down the computational time of the Bayesian identification to a few days. The proposed approach is applied to Moiré interferometry full field displacement measurements from a traction experiment on a plate with a hole. The laminate with a layup of [45,- 45,0]s is made out of a Toray® T800/3631 graphite/epoxy prepreg. The measured displacement maps are provided in Figure 1. The mean values of the identified properties joint probability density function are in agreement with previous identifications carried out on the same material. Furthermore the probability density function also provides the coefficient of variation with which the properties are identified as well as the correlations between the various properties. We find that while the longitudinal Young’s modulus is identified with good accuracy (low standard deviation), the Poisson’s ration is identified with much higher uncertainty. Several of the properties are also found to be correlated. The identified uncertainty structure of the elastic constants (i.e. variance co-variance matrix) has potential benefits to reliability analyses, by allowing a more accurate description of the input uncertainty. An additional advantage of the Bayesian approach is that it provides a natural way (in the form of the prior probability density function) for accounting for prior information that may be available on the material properties thought. This is of great interest for reducing the uncertainty on properties that can only be determined with low confidence from the plate with a hole experiment, such as Poisson’s ratio or transverse Young’s modulus in our case.

Use of aluminum oxide as a permeation barrier for producing thin films on aluminum substrates

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

Provo, James L., E-mail: jlprovo@verizon.net

2016-07-15

Aluminum has desirable characteristics of good thermal properties, good electrical characteristics, good optical properties, and the characteristic of being nonmagnetic and having a low atomic weight (26.98 g atoms), but because of its low melting point (660 °C) and ability as a reactive metal to alloy with most common metals in use, it has been ignored as a substrate material for use in processing thin films. The author developed a simple solution to this problem, by putting a permeation barrier of alumina (Al{sub 2}O{sub 3}) onto the surface of pure Al substrates by using a standard chemical oxidation process of the surfacemore » (i.e., anodization), before additional film deposition of reactive metals at temperatures up to 500 °C for 1-h, without the formation of alloys or intermetallic compounds to affect the good properties of Al substrates. The chromic acid anodization process used (MIL-A-8625) produced a film barrier of ∼(500–1000) nm of alumina. The fact that refractory Al{sub 2}O{sub 3} can inhibit the reaction of metals with Al at temperatures below 500 °C suggests that Al is a satisfactory substrate if properly oxidized prior to film deposition. To prove this concept, thin film samples of Cr, Mo, Er, Sc, Ti, and Zr were prepared on anodized Al substrates and studied by x-ray diffraction, Rutherford ion back scattering, and Auger/argon sputter surface profile analysis to determine any film substrate interactions. In addition, a major purpose of our study was to determine if ErD{sub 2} thin films could be produced on Al substrates with fully hydrided Er films. Thus, a thin film of ErD{sub 2} on an anodized Al substrate was prepared and studied, with and without the alumina permeation barrier. Films for study were prepared on 1.27 cm diameter Al substrates with ∼500 nm of the metals studied after anodization. Substrates were weighed, cleaned, and vacuum fired at 500 °C prior to use. The Al substrates were deposited using standard electron beam cold crucible evaporation techniques, and after deposition the Er film was hydrided with D{sub 2} gas using a standard nonair exposure hydriding technique. All processing was conducted in an all metal ion pumped ultrahigh vacuum system. Results showed that e-beam deposition of films studied onto Al substrates could be successfully performed, if a permeation barrier of Al{sub 2}O{sub 3} from 500 to 1000 nm was made prior to thin film deposition up to temperatures of 500 °C for 1-h. Hydrides also, could be produced with full gas/metal atomic ratios of ∼2.0 as evidenced by the ErD{sub 2} films produced. Thus, the use of a simple permeation barrier of Al{sub 2}O{sub 3} on Al substrates prior to additional metal film deposition was proven to be a successful method of producing both thin metal films and hydride films of various types for many applications.« less

Applications of nanotechnology in wastewater treatment--a review.

PubMed

Bora, Tanujjal; Dutta, Joydeep

2014-01-01

Water on Earth is a precious and finite resource, which is endlessly recycled in the water cycle. Water, whose physical, chemical, or biological properties have been altered due to the addition of contaminants such as organic/inorganic materials, pathogens, heavy metals or other toxins making it unsafe for the ecosystem, can be termed as wastewater. Various schemes have been adopted by industries across the world to treat wastewater prior to its release to the ecosystem, and several new concepts and technologies are fast replacing the traditional methods. This article briefly reviews the recent advances and application of nanotechnology for wastewater treatment. Nanomaterials typically have high reactivity and a high degree of functionalization, large specific surface area, size-dependent properties etc., which makes them suitable for applications in wastewater treatment and for water purification. In this article, the application of various nanomaterials such as metal nanoparticles, metal oxides, carbon compounds, zeolite, filtration membranes, etc., in the field of wastewater treatment is discussed.

One dimensional metallic edges in atomically thin WSe2 induced by air exposure

NASA Astrophysics Data System (ADS)

Addou, Rafik; Smyth, Christopher M.; Noh, Ji-Young; Lin, Yu-Chuan; Pan, Yi; Eichfeld, Sarah M.; Fölsch, Stefan; Robinson, Joshua A.; Cho, Kyeongjae; Feenstra, Randall M.; Wallace, Robert M.

2018-04-01

Transition metal dichalcogenides are a unique class of layered two-dimensional (2D) crystals with extensive promising applications. Tuning the electronic properties of low-dimensional materials is vital for engineering new functionalities. Surface oxidation is of particular interest because it is a relatively simple method of functionalization. By means of scanning probe microscopy and x-ray photoelectron spectroscopy, we report the observation of metallic edges in atomically thin WSe2 monolayers grown by chemical vapor deposition on epitaxial graphene. Scanning tunneling microscopy shows structural details of WSe2 edges and scanning tunneling spectroscopy reveals the metallic nature of the oxidized edges. Photoemission demonstrates that the formation of metallic sub-stoichiometric tungsten oxide (WO2.7) is responsible for the high conductivity measured along the edges. Ab initio calculations validate the susceptibility of WSe2 nanoribbon edges to oxidation. The zigzag terminated edge exhibits metallic behavior prior the air-exposure and remains metallic after oxidation. Comprehending and exploiting this property opens a new opportunity for application in advanced electronic devices.

Impact of fire on macropore flow and the hydraulic conductivity of near-surface blanket peat

NASA Astrophysics Data System (ADS)

Holden, Joseph; Wearing, Catherine; Palmer, Sheila; Jackson, Benjamin; Johnston, Kerrylyn; Brown, Lee

2013-04-01

Peatlands can be subject to wildfire or deliberate burning in many locations. Wildfires are known to impact soil properties and runoff production in most soil types but relatively little work has been conducted on peatlands. Furthermore in large parts of the UK uplands prescribed vegetation burning on peat has taken place at regular intervals (e.g. every 8-25 years) on patches of around 300-900 sq. metres over the past century to support increased grouse populations for sport shooting. However, there have been few studies on how these prescribed fires influence near-surface hydrology. It is known that macropores transport a large proportion of flow in near-surface peat layers and we investigated their role in flow transport for fire sites using tension infiltrometers. Measurements were performed, at replicated hillslope positions to control for slope position effects, on unburnt peat (U) and where prescribed burning had taken place two years (P2), four years (P4) and >15 years (P15+) prior to sampling. For the prescribed burning plots, vegetation burning had also occurred at around a 15-20 year interval for most of the past century. We also sampled a nearby wildfire site (W) with the same sampling design where wildfire had occurred four months prior to sampling. Both the contribution of macropore flow to overall infiltration, and the saturated hydraulic conductivity, were significantly lower in the recently burnt sites (W, P2, P4), compared to P15+ and U. There was no significant difference in macropore flow contributions, effective macroporosity and saturated hydraulic conductivity between P15+ and U. The results suggest fire influences the near-surface hydrological functioning of peatlands but that 'recovery' for some hydrological processes to prescribed vegetation burning may be possible within two decades if there are no further fires.

TRANSFER EFFICIENCIES OF PESTICIDES FROM HOUSEHOLD FLOORING SURFACES TO FOODS

EPA Science Inventory

The transfer of pesticides from household surfaces to foods was measured to determine if excess dietary exposure potentially occurs when children's foods contact contaminated surfaces prior to being. Three common household surfaces (ceramic tile, hardwood flooring, and carpet) w...

Train-to-train rear end impact tests - volume I - pre-impact determination of vehicle properties

DOT National Transportation Integrated Search

1999-03-31

This final report documents these nine tests. Volume I, Pre-Impact Determination of Vehicle Properties, summarizes the vehicle properties obtained prior to the impact tests. These vehicle properties were used in computer simulation of the impact test...

Flight and ground tests of a very low density elastomeric ablative material

NASA Technical Reports Server (NTRS)

Olsen, G. C.; Chapman, A. J., III

1972-01-01

A very low density ablative material, a silicone-phenolic composite, was flight tested on a recoverable spacecraft launched by a Pacemaker vehicle system; and, in addition, it was tested in an arc heated wind tunnel at three conditions which encompassed most of the reentry heating conditions of the flight tests. The material was composed, by weight, of 71 percent phenolic spheres, 22.8 percent silicone resin, 2.2 percent catalyst, and 4 percent silica fibers. The tests were conducted to evaluate the ablator performance in both arc tunnel and flight tests and to determine the predictability of the albator performance by using computed results from an existing one-dimensional numerical analysis. The flight tested ablator experienced only moderate surface recession and retained a smooth surface except for isolated areas where the char was completely removed, probably following reentry and prior to or during recovery. Analytical results show good agreement between arc tunnel and flight test results. The thermophysical properties used in the analysis are tabulated.

InGaN/GaN quantum dots as optical probes for the electric field at the GaN/electrolyte interface

NASA Astrophysics Data System (ADS)

Teubert, J.; Koslowski, S.; Lippert, S.; Schäfer, M.; Wallys, J.; Dimitrakopulos, G.; Kehagias, Th.; Komninou, Ph.; Das, A.; Monroy, E.; Eickhoff, M.

2013-08-01

We investigated the electric-field dependence of the photoluminescence-emission properties of InGaN/GaN quantum dot multilayers in contact with an electrolyte. Controlled variations of the surface potential were achieved by the application of external electric fields using the electrolytic Schottky contact and by variation of the solution's pH value. Prior to characterization, a selective electrochemical passivation process was required to suppress leakage currents. The quantum dot luminescence is strongly affected by surface potential variations, i.e., it increases exponentially with cathodic bias and acidic pH values. The results cannot be explained by a modification of intra-dot polarization induced electric fields via the quantum confined Stark effect but are attributed to the suppression/enhancement of non-radiative recombination processes, i.e., mainly hole transfer into the electrolyte. The results establish a link between the photoluminescence intensity and the magnitude of electric fields at the semiconductor/electrolyte interface.

Effect of Repeated Sterilization Cycles on the Physical Properties of Scaling Instruments: A Scanning Electron Microscopy Study

PubMed Central

Porto, Alessandra Nogueira; Borges, Álvaro Henrique; Semenoff-Segundo, Alex; Raslan, Suzane A; Pedro, Fábio Luis Miranda; Jorge, Antônio Olavo Cardoso; Bandeca, Matheus Coelho

2015-01-01

Background: Repeated sterilizations cycles cause undesirable alterations in the material properties of the instruments, such as corrosion, alterations in the hardness of the metal and the loss of the cutting sharpness of the instrument. This research examined the effect of repeated dry heat sterilization and autoclaves cycles on carbon steel (CS) and stainless steel (SS) curettes during the scaling and root planning. Materials and Methods: A total of 77 Gracey curettes were used in this study. Of these, 35 were SS and 42 were CS curettes submitted in different process: Dry heat, autoclave, inhibition of corrosion and autoclave, scaling, root planning and dry heat, scaling, root planning, inhibition of corrosion and autoclave. The inhibition of corrosion used on the carbon curettes (prior to sterilization in the autoclave) was sodium nitrite at 2%. The curettes received 10 consecutive cycles of sterilization and after that the cutting edges were examined in the electronic microscope, at 60 and 100 magnification times. Results: The images were evaluated by three independent examiners, who compared the photographs of each group with the control group. Conclusion: The surface corrosion products and a deterioration of the edges were observed and the results showed that the SS curettes suffered little alteration with sterilization, scaling, root planning whereas the CS curettes were visibly affected by sterilization in the autoclave, but when the inhibition of corrosion was used prior to the sterilization, the oxidation was considerably reduced. PMID:26028893

Effect of high pressure homogenization on the structure and the interfacial and emulsifying properties of β-lactoglobulin.

PubMed

Ali, Ali; Le Potier, Isabelle; Huang, Nicolas; Rosilio, Véronique; Cheron, Monique; Faivre, Vincent; Turbica, Isabelle; Agnely, Florence; Mekhloufi, Ghozlene

2018-02-15

The effect of high pressure homogenization (HPH) on the structure of β-lactoglobulin (β-lg) was studied by combining spectroscopic, chromatographic, and electrophoretic methods. The consequences of the resulting structure modifications on oil/water (O/W) interfacial properties were also assessed. Moderated HPH treatment (100 MPa/4 cycles) showed no significant modification of protein structure and interfacial properties. However, a harsher HPH treatment (300 MPa/5 cycles) induced structural transformation, mainly from β-sheets to random coils, wide loss in lipocalin core, and protein aggregation via intermolecular disulfide bridges. HPH-modified β-lg displayed higher surface hydrophobicity leading to a faster adsorption rate at the interface and an earlier formation of an elastic interfacial film at C β-lg  = 0.1 wt%. However, no modification of the interfacial properties was observed at C β-lg  = 1 wt%. At this protein concentration, the prior denaturation of β-lg by HPH did not modify the droplet size of nanoemulsions prepared with these β-lg solutions as the aqueous phases. A slightly increased creaming rate was however observed. The effects of HPH and heat denaturations appeared qualitatively similar, but with differences in their extent. Copyright © 2017 Elsevier B.V. All rights reserved.

Surface Functionalization of WO3 Thin Films with (3-Aminopropyl)triethoxysilane and Succinic Anhydride

NASA Astrophysics Data System (ADS)

Ta, Thi Kieu Hanh; Tran, Thi Nhu Hoa; Tran, Quang Minh Nhat; Pham, Duy Phong; Pham, Kim Ngoc; Cao, Thi Thanh; Kim, Yong Soo; Tran, Dai Lam; Ju, Heongkyu; Phan, Bach Thang

2017-06-01

We report effects of oxygen plasma treatment on the surface functionalization of WO3 thin films with (3-aminopropyl)triethoxysilane (APTES) and succinic anhydride (SA). X-ray diffraction and x-ray photoelectron spectroscopy results indicate the existence of the WO3 phase. Fourier transform infrared spectroscopy measurement shows clear bands at 1040 cm-1 (Si-O-Si), 1556 cm-1 (N-H), 1655 cm-1 (C=O), 2937 cm-1 (C-H) and 3298 cm-1 (N-H), confirming the surface functionalization efficiency enhanced by prior treatment of oxygen plasma. It thus follows that the prior oxygen plasma treatment activates hydroxylation with more -OH groups on the WO3 surface, which can pave a highly efficient way to the surface functionalization by APTES and SA.

32 CFR 34.21 - Real property and equipment.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 1 2011-07-01 2011-07-01 false Real property and equipment. 34.21 Section 34.21... Requirements Property Standards § 34.21 Real property and equipment. (a) Prior approval for acquisition with Federal funds. Recipients may purchase real property or equipment in whole or in part with Federal funds...

32 CFR 34.21 - Real property and equipment.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 32 National Defense 1 2012-07-01 2012-07-01 false Real property and equipment. 34.21 Section 34.21... Requirements Property Standards § 34.21 Real property and equipment. (a) Prior approval for acquisition with Federal funds. Recipients may purchase real property or equipment in whole or in part with Federal funds...

32 CFR 34.21 - Real property and equipment.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 1 2010-07-01 2010-07-01 false Real property and equipment. 34.21 Section 34.21... Requirements Property Standards § 34.21 Real property and equipment. (a) Prior approval for acquisition with Federal funds. Recipients may purchase real property or equipment in whole or in part with Federal funds...

32 CFR 34.21 - Real property and equipment.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 32 National Defense 1 2014-07-01 2014-07-01 false Real property and equipment. 34.21 Section 34.21... Requirements Property Standards § 34.21 Real property and equipment. (a) Prior approval for acquisition with Federal funds. Recipients may purchase real property or equipment in whole or in part with Federal funds...

32 CFR 34.21 - Real property and equipment.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 1 2013-07-01 2013-07-01 false Real property and equipment. 34.21 Section 34.21... Requirements Property Standards § 34.21 Real property and equipment. (a) Prior approval for acquisition with Federal funds. Recipients may purchase real property or equipment in whole or in part with Federal funds...

Enhancement in microstructural and optoelectrical properties of thermally evaporated CdTe films for solar cells

NASA Astrophysics Data System (ADS)

Chander, Subhash; Dhaka, M. S.

2018-03-01

The optimization of microstructural and optoelectrical properties of a thin layer is an important step prior device fabrication process, so an enhancement in these properties of thermally evaporated CdTe thin films is reported in this communication. The films having thickness 450 nm and 850 nm were deposited on thoroughly cleaned glass and indium tin oxide (ITO) substrates followed by annealing at 450 °C in air atmosphere. These films were characterized for microstructural and optoelectrical properties employing X-ray diffraction, scanning electron microscopy coupled with energy-dispersive spectroscopy, UV-Vis spectrophotometer and source meter. The films found to be have zinc-blende cubic structure with preferred reflection (111) while the crystallographic parameters and direct energy band gap are strongly influenced by the film thickness. The surface morphology studies show that the films are uniform, smooth, homogeneous and nearly dense-packed as well as free from voids and pitfalls as where elemental analysis revealed the presence of Cd and Te element in the deposited films. The electrical analysis showed linear behavior of current with voltage while conductivity is decreased for higher thickness. The results show that the microstructural and optoelectrical properties of CdTe thin layer could be enhanced by varying thickness and films having higher thickness might be processed as promising absorber thin layer to the CdTe-based solar cells.

Biomaterials and bone mechanotransduction

NASA Technical Reports Server (NTRS)

Sikavitsas, V. I.; Temenoff, J. S.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

2001-01-01

Bone is an extremely complex tissue that provides many essential functions in the body. Bone tissue engineering holds great promise in providing strategies that will result in complete regeneration of bone and restoration of its function. Currently, such strategies include the transplantation of highly porous scaffolds seeded with cells. Prior to transplantation the seeded cells are cultured in vitro in order for the cells to proliferate, differentiate and generate extracellular matrix. Factors that can affect cellular function include the cell-biomaterial interaction, as well as the biochemical and the mechanical environment. To optimize culture conditions, good understanding of these parameters is necessary. The new developments in bone biology, bone cell mechanotransduction, and cell-surface interactions are reviewed here to demonstrate that bone mechanotransduction is strongly influenced by the biomaterial properties.

26 CFR 25.2523(f)-1A - Special rule applicable to community property transferred prior to January 1, 1982.

Code of Federal Regulations, 2011 CFR

2011-04-01

... denote the body of property comprehended within the community property system; the expression “separate... property acquired in exchange for it) which is considered as so held is the same proportion of it which the...

26 CFR 25.2523(f)-1A - Special rule applicable to community property transferred prior to January 1, 1982.

Code of Federal Regulations, 2014 CFR

2014-04-01

... denote the body of property comprehended within the community property system; the expression “separate... property acquired in exchange for it) which is considered as so held is the same proportion of it which the...

26 CFR 25.2523(f)-1A - Special rule applicable to community property transferred prior to January 1, 1982.

Code of Federal Regulations, 2012 CFR

2012-04-01

... denote the body of property comprehended within the community property system; the expression “separate... property acquired in exchange for it) which is considered as so held is the same proportion of it which the...

26 CFR 25.2523(f)-1A - Special rule applicable to community property transferred prior to January 1, 1982.

Code of Federal Regulations, 2010 CFR

2010-04-01

... denote the body of property comprehended within the community property system; the expression “separate... property acquired in exchange for it) which is considered as so held is the same proportion of it which the...

26 CFR 25.2523(f)-1A - Special rule applicable to community property transferred prior to January 1, 1982.

Code of Federal Regulations, 2013 CFR

2013-04-01

... denote the body of property comprehended within the community property system; the expression “separate... property acquired in exchange for it) which is considered as so held is the same proportion of it which the...

Correlative atomic force microscopy quantitative imaging-laser scanning confocal microscopy quantifies the impact of stressors on live cells in real-time.

PubMed

Bhat, Supriya V; Sultana, Taranum; Körnig, André; McGrath, Seamus; Shahina, Zinnat; Dahms, Tanya E S

2018-05-29

There is an urgent need to assess the effect of anthropogenic chemicals on model cells prior to their release, helping to predict their potential impact on the environment and human health. Laser scanning confocal microscopy (LSCM) and atomic force microscopy (AFM) have each provided an abundance of information on cell physiology. In addition to determining surface architecture, AFM in quantitative imaging (QI) mode probes surface biochemistry and cellular mechanics using minimal applied force, while LSCM offers a window into the cell for imaging fluorescently tagged macromolecules. Correlative AFM-LSCM produces complimentary information on different cellular characteristics for a comprehensive picture of cellular behaviour. We present a correlative AFM-QI-LSCM assay for the simultaneous real-time imaging of living cells in situ, producing multiplexed data on cell morphology and mechanics, surface adhesion and ultrastructure, and real-time localization of multiple fluorescently tagged macromolecules. To demonstrate the broad applicability of this method for disparate cell types, we show altered surface properties, internal molecular arrangement and oxidative stress in model bacterial, fungal and human cells exposed to 2,4-dichlorophenoxyacetic acid. AFM-QI-LSCM is broadly applicable to a variety of cell types and can be used to assess the impact of any multitude of contaminants, alone or in combination.

Effect of defoliation prior to a frost on postharvest respiration rate, extractable sucrose, and invert sugar concentration of sugarbeet

USDA-ARS?s Scientific Manuscript database

This study investigated the effect of defoliation prior to a frost on postharvest storage properties of sugarbeet (Beta vulgaris L.). Roots of plants with canopies intact until harvest were compared to roots of plants that had been defoliated prior to a frost on multiple harvest dates following a da...

3D microwave tomography of the breast using prior anatomical information

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

Golnabi, Amir H., E-mail: golnabia@montclair.edu; Meaney, Paul M.; Paulsen, Keith D.

2016-04-15

Purpose: The authors have developed a new 3D breast image reconstruction technique that utilizes the soft tissue spatial resolution of magnetic resonance imaging (MRI) and integrates the dielectric property differentiation from microwave imaging to produce a dual modality approach with the goal of augmenting the specificity of MR imaging, possibly without the need for nonspecific contrast agents. The integration is performed through the application of a soft prior regularization which imports segmented geometric meshes generated from MR exams and uses it to constrain the microwave tomography algorithm to recover nearly uniform property distributions within segmented regions with sharp delineation betweenmore » these internal subzones. Methods: Previous investigations have demonstrated that this approach is effective in 2D simulation and phantom experiments and also in clinical exams. The current study extends the algorithm to 3D and provides a thorough analysis of the sensitivity and robustness to misalignment errors in size and location between the spatial prior information and the actual data. Results: Image results in 3D were not strongly dependent on reconstruction mesh density, and the changes of less than 30% in recovered property values arose from variations of more than 125% in target region size—an outcome which was more robust than in 2D. Similarly, changes of less than 13% occurred in the 3D image results from variations in target location of nearly 90% of the inclusion size. Permittivity and conductivity errors were about 5 times and 2 times smaller, respectively, with the 3D spatial prior algorithm in actual phantom experiments than those which occurred without priors. Conclusions: The presented study confirms that the incorporation of structural information in the form of a soft constraint can considerably improve the accuracy of the property estimates in predefined regions of interest. These findings are encouraging and establish a strong foundation for using the soft prior technique in clinical studies, where their microwave imaging system and MRI can simultaneously collect breast exam data in patients.« less

Optimal estimation retrieval of aerosol microphysical properties from SAGE~II satellite observations in the volcanically unperturbed lower stratosphere

NASA Astrophysics Data System (ADS)

Wurl, D.; Grainger, R. G.; McDonald, A. J.; Deshler, T.

2010-05-01

Stratospheric aerosol particles under non-volcanic conditions are typically smaller than 0.1 μm. Due to fundamental limitations of the scattering theory in the Rayleigh limit, these tiny particles are hard to measure by satellite instruments. As a consequence, current estimates of global aerosol properties retrieved from spectral aerosol extinction measurements tend to be strongly biased. Aerosol surface area densities, for instance, are observed to be about 40% smaller than those derived from correlative in situ measurements (Deshler et al., 2003). An accurate knowledge of the global distribution of aerosol properties is, however, essential to better understand and quantify the role they play in atmospheric chemistry, dynamics, radiation and climate. To address this need a new retrieval algorithm was developed, which employs a nonlinear Optimal Estimation (OE) method to iteratively solve for the monomodal size distribution parameters which are statistically most consistent with both the satellite-measured multi-wavelength aerosol extinction data and a priori information. By thus combining spectral extinction measurements (at visible to near infrared wavelengths) with prior knowledge of aerosol properties at background level, even the smallest particles are taken into account which are practically invisible to optical remote sensing instruments. The performance of the OE retrieval algorithm was assessed based on synthetic spectral extinction data generated from both monomodal and small-mode-dominant bimodal sulphuric acid aerosol size distributions. For monomodal background aerosol, the new algorithm was shown to fairly accurately retrieve the particle sizes and associated integrated properties (surface area and volume densities), even in the presence of large extinction uncertainty. The associated retrieved uncertainties are a good estimate of the true errors. In the case of bimodal background aerosol, where the retrieved (monomodal) size distributions naturally differ from the correct bimodal values, the associated surface area (A) and volume densities (V) are, nevertheless, fairly accurately retrieved, except at values larger than 1.0 μm2 cm-3 (A) and 0.05 μm3 cm-3 (V), where they tend to underestimate the true bimodal values. Due to the limited information content in the SAGE II spectral extinction measurements this kind of forward model error cannot be avoided here. Nevertheless, the retrieved uncertainties are a good estimate of the true errors in the retrieved integrated properties, except where the surface area density exceeds the 1.0 μm2 cm-3 threshold. When applied to near-global SAGE II satellite extinction measured in 1999 the retrieved OE surface area and volume densities are observed to be larger by, respectively, 20-50% and 10-40% compared to those estimates obtained by the SAGE~II operational retrieval algorithm. An examination of the OE algorithm biases with in situ data indicates that the new OE aerosol property estimates tend to be more realistic than previous estimates obtained from remotely sensed data through other retrieval techniques. Based on the results of this study we therefore suggest that the new Optimal Estimation retrieval algorithm is able to contribute to an advancement in aerosol research by considerably improving current estimates of aerosol properties in the lower stratosphere under low aerosol loading conditions.

Investigation of the Corrosion Behavior of Poly(Aniline-co-o-Anisidine)/ZnO Nanocomposite Coating on Low-Carbon Steel

NASA Astrophysics Data System (ADS)

Mobin, M.; Alam, R.; Aslam, J.

2016-07-01

A copolymer of aniline (AN) and o-anisidine (OA), Poly(AN-co-OA) and its nanocomposite with ZnO nanoparticles, Poly(AN-co-OA)/ZnO were synthesized by chemical oxidative polymerization using ammonium persulfate as an oxidant in hydrochloric acid medium. The synthesized compounds were characterized using FTIR, XRD, SEM-EDS, TEM, and electrical conductivity techniques. The copolymer and nanocomposite were separately dissolved in N-methyl-2-pyrrolidone and were casted on low-carbon steel specimens using 10% epoxy resin as a binder. The anticorrosive properties of the coatings were studied in different corrosive environments such as 0.1 M HCl, 5% NaCl solution, and distilled water at a temperature of 30 °C by conducting corrosion tests which include immersion test, open circuit potential measurements, potentiodynamic polarization measurements, and atmospheric exposure test. The surface morphology of the coatings prior to and after one-month immersion in corrosive solution was evaluated using SEM. It was observed that the nanocomposite coating exhibited higher corrosion resistance and provided better barrier properties in comparison with copolymer coating. The presence of ZnO nanoparticles improved the anticorrosion properties of copolymer coating in all corrosive media subjected to investigation.

10 CFR 600.321 - Real property and equipment.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Real property and equipment. 600.321 Section 600.321....321 Real property and equipment. (a) Prior approvals for acquisition with Federal funds. Recipients may purchase real property or equipment in whole or in part with Federal funds under an award only...

10 CFR 600.321 - Real property and equipment.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Real property and equipment. 600.321 Section 600.321....321 Real property and equipment. (a) Prior approvals for acquisition with Federal funds. Recipients may purchase real property or equipment in whole or in part with Federal funds under an award only...

10 CFR 600.321 - Real property and equipment.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Real property and equipment. 600.321 Section 600.321....321 Real property and equipment. (a) Prior approvals for acquisition with Federal funds. Recipients may purchase real property or equipment in whole or in part with Federal funds under an award only...

10 CFR 600.321 - Real property and equipment.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 4 2014-01-01 2014-01-01 false Real property and equipment. 600.321 Section 600.321....321 Real property and equipment. (a) Prior approvals for acquisition with Federal funds. Recipients may purchase real property or equipment in whole or in part with Federal funds under an award only...

23 CFR 710.505 - Real property donations.

Code of Federal Regulations, 2014 CFR

2014-04-01

...-aid project may donate the property to the STD. Prior to accepting the property, the owner must be... be informed of his/her right to an appraisal of the property by a qualified appraiser, unless the STD... STD shall develop sufficient documentation to indicate compliance with paragraph (a) of this section...

23 CFR 710.505 - Real property donations.

Code of Federal Regulations, 2011 CFR

2011-04-01

...-aid project may donate the property to the STD. Prior to accepting the property, the owner must be... be informed of his/her right to an appraisal of the property by a qualified appraiser, unless the STD... STD shall develop sufficient documentation to indicate compliance with paragraph (a) of this section...

23 CFR 710.505 - Real property donations.

Code of Federal Regulations, 2013 CFR

2013-04-01

...-aid project may donate the property to the STD. Prior to accepting the property, the owner must be... be informed of his/her right to an appraisal of the property by a qualified appraiser, unless the STD... STD shall develop sufficient documentation to indicate compliance with paragraph (a) of this section...

Bioactivity of sol-gel-derived TiO2 coating on polyetheretherketone: In vitro and in vivo studies.

PubMed

Shimizu, Takayoshi; Fujibayashi, Shunsuke; Yamaguchi, Seiji; Yamamoto, Koji; Otsuki, Bungo; Takemoto, Mitsuru; Tsukanaka, Masako; Kizuki, Takashi; Matsushita, Tomiharu; Kokubo, Tadashi; Matsuda, Shuichi

2016-04-15

A polyetheretherketone (PEEK) surface was modified using a sol-gel-derived TiO2 coating in order to confer bone-bonding ability. To enhance the bonding strength of the coating layer, pretreatment with either O2 plasma or sandblasting was performed prior to sol-gel coating. Additionally, post-treatment with acid was carried out to confer apatite (calcium phosphate)-forming ability to the surface. Biomechanical and histological analyses performed using an in vivo rabbit tibia model showed that PEEK surfaces modified with sol-gel-derived TiO2 and acid post-treatment had better bone-bonding properties than uncoated PEEK surfaces. These modified surfaces also performed well in terms of their in vitro cell responses due to their modified surface chemistries and topographies. Although O2 plasma or sandblasting treatment were, for the most part, equivocal in terms of performance, we conclude that sol-gel-derived TiO2 coating followed by acid post-treatment significantly improves the bone bonding ability of PEEK surfaces, thus rendering them optimal for their use in surgical implants. The role of polyetheretherketone (PEEK) as an alternative biomaterial to conventional metallic implant materials has become increasingly important. However, its low bone bonding ability is yet to be resolved. This in vivo and in vitro investigation on the functionalization of PEEK surfaces highlights the utility of this material in clinical interventions that require implants, and may extend range of applications of PEEK. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Train-to-train rear end impact tests - volume II - impact test summaries

DOT National Transportation Integrated Search

1977-03-31

This final report documents these nine tests. Volume I, Pre-Impact Determination of Vehicle Properties, summarizes the vehicle properties obtained prior to the impact tests. These vehicle properties were used in computer simulation of the impact test...

Robotic Reconnaissance Missions to Small Bodies and Their Potential Contributions to Human Exploration

NASA Technical Reports Server (NTRS)

Abell, P. A.; Rivkin, A. S.

2015-01-01

Introduction: Robotic reconnaissance missions to small bodies will directly address aspects of NASA's Asteroid Initiative and will contribute to future human exploration. The NASA Asteroid Initiative is comprised of two major components: the Grand Challenge and the Asteroid Mission. The first component, the Grand Challenge, focuses on protecting Earth's population from asteroid impacts by detecting potentially hazardous objects with enough warning time to either prevent them from impacting the planet, or to implement civil defense procedures. The Asteroid Mission involves sending astronauts to study and sample a near- Earth asteroid (NEA) prior to conducting exploration missions of the Martian system, which includes Phobos and Deimos. The science and technical data obtained from robotic precursor missions that investigate the surface and interior physical characteristics of an object will help identify the pertinent physical properties that will maximize operational efficiency and reduce mission risk for both robotic assets and crew operating in close proximity to, or at the surface of, a small body. These data will help fill crucial strategic knowledge gaps (SKGs) concerning asteroid physical characteristics that are relevant for human exploration considerations at similar small body destinations. Small Body Strategic Knowledge Gaps: For the past several years NASA has been interested in identifying the key SKGs related to future human destinations. These SKGs highlight the various unknowns and/or data gaps of targets that the science and engineering communities would like to have filled in prior to committing crews to explore the Solar System. An action team from the Small Bodies Assessment Group (SBAG) was formed specifically to identify the small body SKGs under the direction of the Human Exploration and Operations Missions Directorate (HEOMD), given NASA's recent interest in NEAs and the Martian moons as potential human destinations [1]. The action team organized the SKGs into four broad themes: 1) Identify human mission targets; 2) Understand how to work on and interact with the small body surface; 3) Understand the small body environment and its potential risk/benefit to crew, systems, and operational assets; and 4) Understand the small body resource potential. Each of these themes were then further subdivided into categories to address specific SKG issues. Robotic Precursor Contributions to SKGs: Robotic reconnaissance missions should be able to address specific aspects related to SKG themes 1 through 4. Theme 1 deals with the identification of human mission targets within the NEA population. The current guideline indicates that human missions to fastspinning, tumbling, or binary asteroids may be too risky to conduct successfully from an operational perspective. However, no spacecraft mission has been to any of these types of NEAs before. Theme 2 addresses the concerns about interacting on the small body surface under microgravity conditions, and how the surface and/or sub-surface properties affect or restrict the interaction for human exploration. The combination of remote sensing instruments and in situ payloads will provide good insight into the asteroid's surface and subsurface properties. SKG theme 3 deals with the environment in and around the small body that may present a nuisance or hazard to any assets operating in close proximity. Impact and surface experiments will help address issues related to particle size, particle longevity, internal structure, and the near-surface mechanical stability of the asteroid. Understanding or constraining these physical characteristics are important for mission planning. Theme 4 addresses the resource potential of the small body. This is a particularly important aspect of human exploration since the identification and utilization of resources is a key aspect for deep space mission architectures to the Martian system (i.e., Phobos and Deimos). Conclusions: Robotic reconnaissance of small bodies can provide a wealth of information relevant to the science and planetary defense of NEAs. However, such missions to investigate NEAs can also provide key insights into small body strategic knowledge gaps and contribute to the overall success for human exploration missions to asteroids.

Plasma sprayed hydroxyapatite coatings on titanium substrates. Part 2: optimisation of coating properties.

PubMed

Tsui, Y C; Doyle, C; Clyne, T W

1998-11-01

Heat treatment and the introduction of a Ti bond coat have been applied to hydroxyapatite (HA) coatings sprayed using different plasma powers and gas mixtures. Attempts were made in this way to achieve optimal coating properties for orthopaedic implants. In particular, the effects on the degree of crystallinity, the adhesion, the OH ion content and the purity were evaluated. Heat treatment at 700 C for 1 h in air proved to be effective in increasing the crystallinity, regaining the OH- ion and removing other non-HA compounds, although it caused a significant decrease in the degree of adhesion (interfacial fracture toughness) for those specimens sprayed at high powers. This heat treatment was found to induce significant transformation of amorphous HA to the crystalline form, while not detrimentally changing the properties of the underlying Ti-6Al-4V substrates. Precoating with a 100 microm Ti layer increased the adhesion of the HA coatings on Ti-6Al-4V substrates, primarily by providing a rougher surface and promoting better mechanical interlocking. Changes in coating properties during immersion in biological fluids were also studied and were found to depend critically on the chemical composition of the fluids. Small precipitates formed on the coating surfaces when immersed in Ringers solution. These might account for the apparent drop in the degree of crystallinity when measured using X-ray diffraction. A significant drop in the interfacial adhesion was found for those coatings sprayed at high powers. This could be offset by prior precoating with a titanium bond coat and suitable heat treatment. In summary, the following processing sequence is suggested in order to achieve optimum coating properties: precoating the substrate with a layer of Ti (approximately 100 microm), spraying HA at a sufficiently high-power level (depending on particle size and gas mixture) and heat treatment at 700 degrees C for 1 h in air.

Brazed graphite/refractory metal composites for first-wall protection elements

NASA Astrophysics Data System (ADS)

Šmid, I.; Croessmann, C. D.; Salmonson, J. C.; Whitley, J. B.; Kny, E.; Reheis, N.; Kneringer, G.; Nickel, H.

1991-03-01

The peak surface heat flux deposition on divertor elements of near term fusion devices is expected to exceed 10 MW/m 2. The needed reliability of brazed plasma interactive components, particularly under abnormal operating conditions with peak surface temperatures well beyond 1000°C, makes refractory metallic substrates and brazes with a high melting point very attractive. TZM, a high temperature alloy of molybdenum, and isotropic graphite, materials very closely matched in their thermal expansion, were brazed with four high-temperature brazes. The brazes used were Zr, 90Ni/10Ti, 90Cu/10Ti and 70Ag/27Cu/3Ti (nominal composition prior to brazing, wt%). The resulting composite tiles of 50 × 50 mm2 with a TZM thickness of 5 mm and a graphite thickness of 10 mm have been tested in high heat flux simulation for their thermal fatigue properties. Up to 600 loading cycles were carried out with an average heat flux of 10 MW/m 2 for 0.5 s pulses. The maximum surface temperature was 1100°C. In support of the experiment, the thermal response and temperature gradients of the samples were investigated using a finite element model.

Electricity from Coal Combustion: Improving the hydrophobicity of oxidized coals

NASA Astrophysics Data System (ADS)

Seehra, Mohindar; Singh, Vivek

2011-03-01

To reduce pollution and improve efficiency, undesirable mineral impurities in coals are usually removed in coal preparation plants prior to combustion first by crushing and grinding coals followed by gravity separation using surfactant aided water flotation. However certain coals in the US are not amendable to this process because of their poor flotation characteristics resulting in a major loss of an energy resource. This problem has been linked to surface oxidation of mined coals which make these coals hydrophilic. In this project, we are investigating the surface and water flotation properties of the eight Argonne Premium (AP) coals using x-ray diffraction, IR spectroscopy and zeta potential measurements. The role of the surface functional groups, (phenolic -OH and carboxylic -COOH), produced as a result of chemisorptions of O2 on coals in determining their flotation behavior is being explored. The isoelectric point (IEP) in zeta potential measurements of good vs. poor floaters is being examined in order to improved the hydrophobicity of poor floating coals (e.g. Illinois #6). Results from XRD and IR will be presented along with recent findings from zeta potential measurements, and use of additives to improve hydrophobicity. Supported by USDOE/CAST, Contract #DE-FC26-05NT42457.

Optical and other property changes of M-50 bearing steel surfaces for different lubricants and additive prior to scuffing

NASA Technical Reports Server (NTRS)

Lauer, J. L.; Marxer, N.

1984-01-01

An ester lubricant base oil containing one or more standard additives to protect against wear, corrosion, and oxidation was used in an experimental ball/plate elastohydrodynamic contact under load and speed conditions such as to induce scuffing failure in short times. Both the ball and the plate were of identically treated M-50 steel. After various periods of operating time the wear track on the plate was examined with an interference microscope of plus or minus 30 A depth resolution and sometimes also with a scanning ellipsometer and an Auger spectrometer. The optically deduced surface profiles varied with wavelength, indicating the presence of surface coatings, which were confirmed by the other instruments. As scuffing was approached, a thin (approximately A) oxide layer and a carbide layer formed in the wear track in particular when tricresylphosphate antiwear additive was present in the lubricant. The rates of the formation of these layers and their reactivity toward dilute alcholic HCl depended strongly on the lubricant and additives. Based on these results suggestions for improved formulations and a test method for bearing reliability could be proposed.

Synthesis and characterization of Ni NPs-doped silica-titania nanocomposites: structural, optical and photocatalytic properties

NASA Astrophysics Data System (ADS)

Islam, S.; Bidin, N.; Osman, S. S.; Krishnan, G.; Salim, A. A.; Riaz, S.; Suan, L. P.; Naseem, S.; Sanagi, M. M.

2017-01-01

The synthesis of Ni-doped silica-titania nanocomposite is performed by sol-gel method. The samples prior and after heat treatment at 300 °C for 1 h are characterized by analytical instrumental techniques. FE-SEM and AFM results indicate the regular morphology with low surface roughness without any cracks. EDX analysis verifies the formation of nanocomposites. XRD of the films reveals crystalline titania phases after annealing at 300 °C. The FTIR confirms the bond linkage between silica, titania and nickel molecules. High surface area 155 m2/g, pore volume of 0.2 cm3/g and pore diameter of 48.10 Å are obtained after heat treatment. The magnetic results show that the composite content is reminiscent of ferromagnetic hysteresis loop, with remanence magnetization Mr of 45.35 and 13.20 emu/g for both samples. The organic dye phenol red is used for the evaluation of photocatalytic activity of the synthesized magnetic material. The homogeneous surface morphology, crystalline nature, good solubility of magnetic nanoparticles into the silica-titania matrix show that the Ni/SiO2-TiO2 magnetic photocatalyst can be efficient and reusable.

Electronic and Ionic Conductors from Ordered Microporous Materials

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

Dincă, Mircea

The proposed work aimed to establish metal-organic frameworks (MOFs) as new classes of high-surface area microporous electronic and ionic conductors. MOFs are crystalline materials with pore sizes ranging from 0.2 to ~ 2 nm (or larger for the latter) defined by inorganic or organic building blocks connected by rigid organic linkers. Myriad applications have been found or proposed for these materials, yet those that require electron transport or conductivity in combination with permanent porosity still lag behind because the vast majority of known frameworks are electrical insulators. Prior to our proposal and subsequent work, there were virtually no studies exploringmore » the possibility of electronic delocalization in these materials. Therefore, our primary goal was to understand and control, at a fundamental level, the electron and ion transport properties of this class of materials, with no specific application proposed, although myriad applications could be envisioned for high surface area conductors. Our goals directly addressed one of the DOE-identified Grand Challenges for Basic Energy Sciences: designing perfect atom- and energy-efficient syntheses of revolutionary new forms of matter with tailored properties. Indeed, the proposed work is entirely synthetic in nature; owing to the molecular nature of the building blocks in MOFs, there is the possibility of unprecedented control over the structure and properties of solid crystalline matter. The goals also tangentially addressed the Grand Challenge of controlling materials processes at the level of electrons: the scope of our program is to create new materials where charges (electrons and/or ions) move according to predefined pathways.« less

Nanopatterning of Group V Elements for Tailoring the Electronic Properties of Semiconductors by Monolayer Doping.

PubMed

Thissen, Peter; Cho, Kyeongjae; Longo, Roberto C

2017-01-18

Control of the electronic properties of semiconductors is primarily achieved through doping. While scaling down the device dimensions to the molecular regime presents an increasing number of difficulties, doping control at the nanoscale is still regarded as one of the major challenges of the electronic industry. Within this context, new techniques such as monolayer doping (MLD) represent a substantial improvement toward surface doping with atomic and specific doping dose control at the nanoscale. Our previous work has explained in detail the atomistic mechanism behind MLD by means of density-functional theory calculations (Chem. Mater. 2016, 28, 1975). Here, we address the key questions that will ultimately allow one to optimize the scalability of the MLD process. First, we show that dopant coverage control cannot be achieved by simultaneous reaction of several group V elements, but stepwise reactions make it possible. Second, using ab initio molecular dynamics, we investigate the thermal decomposition of the molecular precursors, together with the stability of the corresponding binary and ternary dopant oxides, prior to the dopant diffusion into the semiconductor surface. Finally, the effect of the coverage and type of dopant on the electronic properties of the semiconductor is also analyzed. Furthermore, the atomistic characterization of the MLD process raises unexpected questions regarding possible crystal damage effects by dopant exchange with the semiconductor ions or the final distribution of the doping impurities within the crystal structure. By combining all our results, optimization recipes to create ultrashallow doped junctions at the nanoscale are finally proposed.

Is an Illustration Always Worth Ten Thousand Words? Effects of Prior Knowledge, Learning Style and Multimedia Illustrations on Text Comprehension.

ERIC Educational Resources Information Center

Ollerenshaw, Alison; Aidman, Eugene; Kidd, Garry

1997-01-01

This study examined comprehension in four groups of undergraduates under text only, multimedia, and two diagram conditions of text supplementation. Results indicated that effects of text supplementation are mediated by prior knowledge and learning style: multimedia appears more beneficial to surface learners with little prior knowledge and makes…

Laser surface modification of Ti--6Al--4V: wear and corrosion characterization in simulated biofluid.

PubMed

Singh, Raghuvir; Kurella, A; Dahotre, Narendra B

2006-07-01

Laser surface melting (LSM) of Ti-6Al-4V is performed in argon to improve its properties, such as microstructure, corrosion, and wear for biomedical applications. Corrosion behavior is investigated by conducting electrochemical polarization experiments in simulated body fluid (Ringer's solution) at 37 C. Wear properties are evaluated in Ringer's solution using pin-on-disc apparatus at a slow speed. Untreated Ti-6Al-4V contains alpha+beta phase. After laser surface melting, it transforms to acicular alpha embedded in the prior beta matrix. Grain growth in the range of 65-89 microm with increase in laser power from 800 to 1500 W due to increase in associated temperature is observed. The hardness of as-laserprocessed Ti-6Al-4V alloy is more (275-297 HV) than that of the untreated alloy (254 HV). Passivation currents are significantly reduced to < 4.3 microA/cm2 after laser treatment compared to untreated Ti-6Al-4V (approximately 12 microA/cm2). The wear resistance of laser-treated Ti-6Al-4V in simulated body fluid is enhanced compared to that of the untreated one. It is the highest for the one that is processed at a laser power of 800 W. Typical micro-cutting features of abrasive wear is the prominent mechanism of wear in both untreated and as-laser-treated Ti-6Al-4V. Fragmentation of wear debris assisted by microcracking was responsible for mass loss during the wear of untreated Ti-6Al-4V in Ringer's solution.

Multimodal optical measurement in vitro of surface deformations and wall thickness of the pressurized aortic arch

NASA Astrophysics Data System (ADS)

Genovese, Katia; Humphrey, Jay D.

2015-04-01

Computational modeling of arterial mechanics continues to progress, even to the point of allowing the study of complex regions such as the aortic arch. Nevertheless, most prior studies assign homogeneous and isotropic material properties and constant wall thickness even when implementing patient-specific luminal geometries obtained from medical imaging. These assumptions are not due to computational limitations, but rather to the lack of spatially dense sets of experimental data that describe regional variations in mechanical properties and wall thickness in such complex arterial regions. In this work, we addressed technical challenges associated with in vitro measurement of overall geometry, full-field surface deformations, and regional wall thickness of the porcine aortic arch in its native anatomical configuration. Specifically, we combined two digital image correlation-based approaches, standard and panoramic, to track surface geometry and finite deformations during pressurization, with a 360-deg fringe projection system to contour the outer and inner geometry. The latter provided, for the first time, information on heterogeneous distributions of wall thickness of the arch and associated branches in the unloaded state. Results showed that mechanical responses vary significantly with orientation and location (e.g., less extensible in the circumferential direction and with increasing distance from the heart) and that the arch exhibits a nearly linear increase in pressure-induced strain up to 40%, consistent with other findings on proximal porcine aortas. Thickness measurements revealed strong regional differences, thus emphasizing the need to include nonuniform thicknesses in theoretical and computational studies of complex arterial geometries.

Comparison of Surface Ground Temperature from Satellite Observations and the Off-Line Land Surface GEOS Assimilation System

NASA Technical Reports Server (NTRS)

Yang, R.; Houser, P.; Joiner, J.

1998-01-01

The surface ground temperature (Tg) is an important meteorological variable, because it represents an integrated thermal state of the land surface determined by a complex surface energy budget. Furthermore, Tg affects both the surface sensible and latent heat fluxes. Through these fluxes. the surface budget is coupled with the atmosphere above. Accurate Tg data are useful for estimating the surface radiation budget and fluxes, as well as soil moisture. Tg is not included in conventional synoptical weather station reports. Currently, satellites provide Tg estimates globally. It is necessary to carefully consider appropriate methods of using these satellite data in a data assimilation system. Recently, an Off-line Land surface GEOS Assimilation (OLGA) system was implemented at the Data Assimilation Office at NASA-GSFC. One of the goals of OLGA is to assimilate satellite-derived Tg data. Prior to the Tg assimilation, a thorough investigation of satellite- and model-derived Tg, including error estimates, is required. In this study we examine the Tg from the n Project (ISCCP DI) data and the OLGA simulations. The ISCCP data used here are 3-hourly DI data (2.5x2.5 degree resolution) for 1992 summer months (June, July, and August) and winter months (January and February). The model Tg for the same periods were generated by OLGA. The forcing data for this OLGA 1992 simulation were generated from the GEOS-1 Data Assimilation System (DAS) at Data Assimilation Office NASA-GSFC. We examine the discrepancies between ISCCP and OLGA Tg with a focus on its spatial and temporal characteristics, particularly on the diurnal cycle. The error statistics in both data sets, including bias, will be estimated. The impact of surface properties, including vegetation cover and type, topography, etc, on the discrepancies will be addressed.

Critical Surface Parameters for the Oxidative Coupling of Methane over the Mn-Na-W/SiO2 Catalyst.

PubMed

Hayek, Naseem S; Lucas, Nishita S; Warwar Damouny, Christine; Gazit, Oz M

2017-11-22

The work here presents a thorough evaluation of the effect of Mn-Na-W/SiO 2 catalyst surface parameters on its performance in the oxidative coupling of methane (OCM). To do so, we used microporous dealuminated β-zeolite (Zeo), or mesoporous SBA-15 (SBA), or macroporous fumed silica (Fum) as precursors for catalyst preparation, together with Mn nitrate, Mn acetate and Na 2 WO 4 . Characterizing the catalysts by inductively coupled plasma-optical emission spectroscopy, N 2 physisorption, X-ray diffraction, high-resolution scanning electron microscopy-energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, and catalytic testing enabled us to identify critical surface parameters that govern the activity and C 2 selectivity of the Mn-Na-W/SiO 2 catalyst. Although the current paradigm views the phase transition of silica to α-cristobalite as the critical step in obtaining dispersed and stable metal sites, we show that the choice of precursors is equally or even more important with respect to tailoring the right surface properties. Specifically, the SBA-based catalyst, characterized by relatively closed surface porosity, demonstrated low activity and low C 2 selectivity. By contrast, for the same composition, the Zeo-based catalyst showed an open surface pore structure, which translated up to fourfold higher activity and enhanced selectivity. By varying the overall composition of the Zeo catalysts, we show that reducing the overall W concentration reduces the size of the Na 2 WO 4 species and increases the catalytic activity linearly as much as fivefold higher than the SBA catalyst. This linear dependence correlates well to the number of interfaces between the Na 2 WO 4 and Mn 2 O 3 species. Our results combined with prior studies lead us to single out the interface between Na 2 WO 4 and Mn 2 O 3 as the most probable active site for OCM using this catalyst. Synergistic interactions between the various precursors used and the phase transition are discussed in detail, and the conclusions are correlated to surface properties and catalysis.

You Only Get One Chance to Make a First Impression: A Quantitative Analysis of Division Officer Fleet Experiences on Surface Warfare Officer Retention

DTIC Science & Technology

2007-03-01

They conclude that the most important contributors to turnover in human services fields are stress, burnout , and lack of job satisfaction...as it relates to performance, satisfaction, and turnover. Lucas (1999) conducted a controlled experiment with college students in an attempt to... dental benefits of service in the military. 6. Prior-Enlisted Status The prior-enlisted status variable is dichotomous, where non-prior=0 and prior=1

41 CFR 109-1.5303 - Procedures.

Code of Federal Regulations, 2011 CFR

2011-01-01

... a larger assembly, a complex operating system, or an older facility. The review of this property will be completed, prior to disposition, when replacing components or when operating systems and... Section 109-1.5303 Public Contracts and Property Management Federal Property Management Regulations System...

41 CFR 109-1.5303 - Procedures.

Code of Federal Regulations, 2012 CFR

2012-01-01

... a larger assembly, a complex operating system, or an older facility. The review of this property will be completed, prior to disposition, when replacing components or when operating systems and... Section 109-1.5303 Public Contracts and Property Management Federal Property Management Regulations System...

41 CFR 109-1.5303 - Procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... a larger assembly, a complex operating system, or an older facility. The review of this property will be completed, prior to disposition, when replacing components or when operating systems and... Section 109-1.5303 Public Contracts and Property Management Federal Property Management Regulations System...

41 CFR 109-1.5303 - Procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... a larger assembly, a complex operating system, or an older facility. The review of this property will be completed, prior to disposition, when replacing components or when operating systems and... Section 109-1.5303 Public Contracts and Property Management Federal Property Management Regulations System...

41 CFR 109-1.5303 - Procedures.

Code of Federal Regulations, 2014 CFR

2014-01-01

... a larger assembly, a complex operating system, or an older facility. The review of this property will be completed, prior to disposition, when replacing components or when operating systems and... Section 109-1.5303 Public Contracts and Property Management Federal Property Management Regulations System...

Optical polarimetric properties of the Echo 2 and PAGEOS 1 engineering surfaces. M.S. Thesis - Virginia Univ.

NASA Technical Reports Server (NTRS)

Lee, R. B., III

1972-01-01

Experimental investigations of the percent polarization of sunlight reflected from the surfaces of each of the Echo 2 Satellite and PAGEOS (Passive Geodetic Earth Orbiting Satellite) were performed to determine the stability of their surfaces in the space environment. The Echo 2 surface material was amorphous phosphate chemically bonded to a rolled aluminum substrate while the PAGEOS 1 surface material is vapor deposited aluminum on a poly (ethylene terephthalate) film. The stability of the satellites' surfaces was analyzed by comparing the light polarizing properties of the satellites, to those of test surfaces representative of the satellites' surfaces. The properties of flat test surfaces were measured experimentally in the laboratory, and the effects of surface strain, surface geometry, and vacuum upon these properties were examined. The laboratory analyses revealed that the polarization properties of the Echo 2 surface were significantly affected by surface geometry and vacuum, and that the properties of the PAGEOS 1 surface were not significantly altered by any of the above mechanisms.

Walnut Hulls Clean Aluminum

NASA Technical Reports Server (NTRS)

Colberg, W. R.; Gordon, G. H.; Jackson, C. H.

1984-01-01

Hulls inflict minimal substrate damage. Walnut hulls found to be best abrasive for cleaning aluminum surfaces prior to painting. Samples blasted with walnut hulls showed no compressive stress of surface.

Integrating prior information into microwave tomography part 2: Impact of errors in prior information on microwave tomography image quality.

PubMed

Kurrant, Douglas; Fear, Elise; Baran, Anastasia; LoVetri, Joe

2017-12-01

The authors have developed a method to combine a patient-specific map of tissue structure and average dielectric properties with microwave tomography. The patient-specific map is acquired with radar-based techniques and serves as prior information for microwave tomography. The impact that the degree of structural detail included in this prior information has on image quality was reported in a previous investigation. The aim of the present study is to extend this previous work by identifying and quantifying the impact that errors in the prior information have on image quality, including the reconstruction of internal structures and lesions embedded in fibroglandular tissue. This study also extends the work of others reported in literature by emulating a clinical setting with a set of experiments that incorporate heterogeneity into both the breast interior and glandular region, as well as prior information related to both fat and glandular structures. Patient-specific structural information is acquired using radar-based methods that form a regional map of the breast. Errors are introduced to create a discrepancy in the geometry and electrical properties between the regional map and the model used to generate the data. This permits the impact that errors in the prior information have on image quality to be evaluated. Image quality is quantitatively assessed by measuring the ability of the algorithm to reconstruct both internal structures and lesions embedded in fibroglandular tissue. The study is conducted using both 2D and 3D numerical breast models constructed from MRI scans. The reconstruction results demonstrate robustness of the method relative to errors in the dielectric properties of the background regional map, and to misalignment errors. These errors do not significantly influence the reconstruction accuracy of the underlying structures, or the ability of the algorithm to reconstruct malignant tissue. Although misalignment errors do not significantly impact the quality of the reconstructed fat and glandular structures for the 3D scenarios, the dielectric properties are reconstructed less accurately within the glandular structure for these cases relative to the 2D cases. However, general agreement between the 2D and 3D results was found. A key contribution of this paper is the detailed analysis of the impact of prior information errors on the reconstruction accuracy and ability to detect tumors. The results support the utility of acquiring patient-specific information with radar-based techniques and incorporating this information into MWT. The method is robust to errors in the dielectric properties of the background regional map, and to misalignment errors. Completion of this analysis is an important step toward developing the method into a practical diagnostic tool. © 2017 American Association of Physicists in Medicine.

10 CFR 600.321 - Real property and equipment.

Code of Federal Regulations, 2010 CFR

2010-01-01

... following: (1) During the time that the real property or equipment is used on the project or program for... 10 Energy 4 2010-01-01 2010-01-01 false Real property and equipment. 600.321 Section 600.321....321 Real property and equipment. (a) Prior approvals for acquisition with Federal funds. Recipients...

41 CFR 102-73.30 - What historic preservation provisions must Federal agencies comply with prior to acquiring...

Code of Federal Regulations, 2014 CFR

2014-01-01

... agencies can find guidance on protecting, enhancing, and preserving historic and cultural property in part... 41 Public Contracts and Property Management 3 2014-01-01 2014-01-01 false What historic...? 102-73.30 Section 102-73.30 Public Contracts and Property Management Federal Property Management...

The susceptibility of weathered versus unweathered schist to biological colonization in the Côa Valley Archaeological Park (north-east Portugal).

PubMed

Marques, Joana; Vázquez-Nion, Daniel; Paz-Bermúdez, Graciela; Prieto, Beatriz

2015-05-01

This study addresses the primary and secondary bioreceptivity of schist used as a support for prehistoric rock art in the Côa Valley Archaeological Park (north-east Portugal) and provides some parameters that can be related to the risk of biologically induced schist weathering. Samples of freshly quarried and naturally weathered schist were characterized in terms of their intrinsic properties and maintained in controlled environmental conditions after inoculation with biofilm-forming cyanobacteria. The physical properties of the studied schist, as well as its abrasion pH, all varied according to the weathering degree of the samples and so did its susceptibility to colonization by biofilm-forming cyanobacteria. Complete separation between weathered and unweathered schist samples in terms of laboratory-induced photosynthetic biomass was obtained by measuring total colour change in the CIE (International Commission on Illumination) L*a*b* colour space. Weathered schist was more bioreceptive than unweathered schist, associated with increased open porosity, water saturation, capillary water and capillarity coefficient and decreased abrasion pH. In the future, it might be possible to determine the susceptibility of schist surfaces to biological colonization through evaluation of colour differences associated with the different weathering degrees presented by those surfaces prior to colonization. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Influence of Ice Cloud Microphysics on Imager-Based Estimates of Earth's Radiation Budget

NASA Astrophysics Data System (ADS)

Loeb, N. G.; Kato, S.; Minnis, P.; Yang, P.; Sun-Mack, S.; Rose, F. G.; Hong, G.; Ham, S. H.

2016-12-01

A central objective of the Clouds and the Earth's Radiant Energy System (CERES) is to produce a long-term global climate data record of Earth's radiation budget from the TOA down to the surface along with the associated atmospheric and surface properties that influence it. CERES relies on a number of data sources, including broadband radiometers measuring incoming and reflected solar radiation and OLR, high-resolution spectral imagers, meteorological, aerosol and ozone assimilation data, and snow/sea-ice maps based on microwave radiometer data. While the TOA radiation budget is largely determined directly from accurate broadband radiometer measurements, the surface radiation budget is derived indirectly through radiative transfer model calculations initialized using imager-based cloud and aerosol retrievals and meteorological assimilation data. Because ice cloud particles exhibit a wide range of shapes, sizes and habits that cannot be independently retrieved a priori from passive visible/infrared imager measurements, assumptions about the scattering properties of ice clouds are necessary in order to retrieve ice cloud optical properties (e.g., optical depth) from imager radiances and to compute broadband radiative fluxes. This presentation will examine how the choice of an ice cloud particle model impacts computed shortwave (SW) radiative fluxes at the top-of-atmosphere (TOA) and surface. The ice cloud particle models considered correspond to those from prior, current and future CERES data product versions. During the CERES Edition2 (and Edition3) processing, ice cloud particles were assumed to be smooth hexagonal columns. In the Edition4, roughened hexagonal columns are assumed. The CERES team is now working on implementing in a future version an ice cloud particle model comprised of a two-habit ice cloud model consisting of roughened hexagonal columns and aggregates of roughened columnar elements. In each case, we use the same ice particle model in both the imager-based cloud retrievals (inverse problem) and the computed radiative fluxes (forward calculation). In addition to comparing radiative fluxes using the different ice cloud particle models, we also compare instantaneous TOA flux calculations with those observed by the CERES instrument.

Structure and corrosion properties of PVD Cr-N coatings

NASA Astrophysics Data System (ADS)

Liu, C.; Bi, Q.; Ziegele, H.; Leyland, A.; Matthews, A.

2002-05-01

PVD Cr-N coatings produced by physical vapor deposition (PVD) are increasingly used for mechanical and tribological applications in various industrial sectors. These coatings are particularly attractive for their excellent corrosion resistance, which further enhances the lifetime and service quality of coated components. PVD Cr-N coated steels in an aqueous solution are usually corroded by galvanic attack via through-coating ``permeable'' defects (e.g., pores). Therefore, the corrosion performance of Cr-N coated steel is determined by a number of variables of the coating properties and corrosive environment. These variables include: (i) surface continuity and uniformity; (ii) through-coating porosity; (iii) film density and chemical stability; (iv) growth stresses; (v) interfacial and intermediate layers; (vi) coating thickness; (vii) coating composition; and (viii) substrate properties. In this article, PVD Cr-N coatings were prepared, by electron-beam PVD and sputter deposition, with different compositions, thicknesses, and surface roughnesses, by changing the N2 flow rate, applying multilayering techniques and changing the substrate finish prior to coating. The microstructure of such coatings is investigated by various analytical techniques such as glancing angle x-ray diffraction and scanning electron microscopy, which are also correlated with the corrosion performance of the coated steel. Both dc polarization and ac impedance spectroscopy were employed to investigate the corrosion resistance of Cr-N coated steel in a 0.5N NaCl solution. It has been found that the N2 flow rate during reactive deposition strongly determines the microstructure of Cr-N coatings (due to the changing nitrogen content in the film) and can thus affect the corrosion resistance of coated systems. The surface finish of the steel substrate also affects the uniformity and coverage of PVD coatings; grooves and inclusions on the original substrate can raise the susceptibility of coated systems to crevice corrosion. Increased coating thickness can also greatly reduce the incidence of through-coating porosity such that the improvement in corrosion performance of thicker Cr-N coatings is significant.

24 CFR 581.4 - Suitability determination.

Code of Federal Regulations, 2010 CFR

2010-04-01

... earlier than six months prior to the expected date when the property will become unutilized or... determination for a particular piece of property, and the reasons for that determination; and (2) The...

Simulating regolith ejecta due to gas impingement

NASA Astrophysics Data System (ADS)

Chambers, Wesley Allen; Metzger, Philip; Dove, Adrienne; Britt, Daniel

2016-10-01

Space missions operating at or near the surface of a planet or small body must consider possible gas-regolith interactions, as they can cause hazardous effects or, conversely, be employed to accomplish mission goals. They are also directly related to a body's surface properties; thus understanding these interactions could provide an additional tool to analyze mission data. The Python Regolith Interaction Calculator (PyRIC), built upon a computational technique developed in the Apollo era, was used to assess interactions between rocket exhaust and an asteroid's surface. It focused specifically on threshold conditions for causing regolith ejecta. To improve this model, and learn more about the underlying physics, we have begun ground-based experiments studying the interaction between gas impingement and regolith simulant. Compressed air, initially standing in for rocket exhaust, is directed through a rocket nozzle at a bed of simulant. We assess the qualitative behavior of various simulants when subjected to a known maximum surface pressure, both in atmosphere and in a chamber initially at vacuum. These behaviors are compared to prior computational results, and possible flow patterns are inferred. Our future work will continue these experiments in microgravity through the use of a drop tower. These will use several simulant types and various pressure levels to observe the effects gas flow can have on target surfaces. Combining this with a characterization of the surface pressure distribution, tighter bounds can be set on the cohesive threshold necessary to maintain regolith integrity. This will aid the characterization of actual regolith distributions, as well as informing the surface operation phase of mission design.

Anisotropic surface chemistry properties and adsorption behavior of silicate mineral crystals.

PubMed

Xu, Longhua; Tian, Jia; Wu, Houqin; Fang, Shuai; Lu, Zhongyuan; Ma, Caifeng; Sun, Wei; Hu, Yuehua

2018-03-07

Anisotropic surface properties of minerals play an important role in a variety of fields. With a focus on the two most intensively investigated silicate minerals (i.e., phyllosilicate minerals and pegmatite aluminosilicate minerals), this review highlights the research on their anisotropic surface properties based on their crystal structures. Four surface features comprise the anisotropic surface chemistry of minerals: broken bonds, energy, wettability, and charge. Analysis of surface broken bond and energy anisotropy helps to explain the cleavage and growth properties of mineral crystals, and understanding surface wettability and charge anisotropy is critical to the analysis of minerals' solution behavior, such as their flotation performance and rheological properties. In a specific reaction, the anisotropic surface properties of minerals are reflected in the adsorption strengths of reagents on different mineral surfaces. Combined with the knowledge of mineral crushing and grinding, a thorough understanding of the anisotropic surface chemistry properties and the anisotropic adsorption behavior of minerals will lead to the development of effective relational models comprising their crystal structure, surface chemistry properties, and targeted reagent adsorption. Overall, such a comprehensive approach is expected to firmly establish the connection between selective cleavage of mineral crystals for desired surfaces and designing novel reagents selectively adsorbed on the mineral surfaces. As tools to characterize the anisotropic surface chemistry properties of minerals, DLVO theory, atomic force microscopy (AFM), and molecular dynamics (MD) simulations are also reviewed. Copyright © 2017 Elsevier B.V. All rights reserved.

The densification, crystallization and mechanical properties of allylhydridopolycarbosilane-derived silicon carbide

NASA Astrophysics Data System (ADS)

Moraes, Kevin V.

Allylhydridopolycarbosilane is a precursor of growing importance in the fabrication of silicon carbide ceramics. However, prior to this study few details were available about the processing-structure-property relationships for this material. In Part 1 of this study the processes of densification and microstructural transformation of the partially pyrolysed amorphous AHPCS-SiC was investigated in the temperature region of 800°C to 1600°C. In Part 2 of this study, mechanical properties, specifically fracture toughness (K1c) and Vickers hardness, were measured on bulk specimens in the temperature range of 1000°C to 1600°C. A combination of X-Ray diffraction (XRD), Transmission Electron Microscopy (TEM), 29Si Nuclear Magnetic Resonance (NMR) and micro Raman spectroscopy, along with simultaneous Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) were used to follow the structural transformation of the partially pyrolysed AHPCS-SiC on several length scales between the temperature of 800 to 1600°C. It was determined that the rate of densification of amorphous AHPCS-SiC, partially pyrolysed to 600°C, depends on the surface to volume ratio. Calculations were preformed that suggested that nucleation of the SiC crystals should occur preferentially on the surface of the powder particles rather than in the bulk. However, TEM on samples heat-treated to 1600°C did not show a preponderance of crystals on the surface of the particles compared to their bulk. Crystallization of beta-SiC occurs at ca. 1250°C, as determined by DSC and supported by NMR and electron diffraction. The average size of the beta-SiC crystallites, as determined by XRD, was ca. 5 nm at 1600°C. Prior to the crystallization of beta-SiC, Raman spectroscopy indicates the presence of carbon clusters in the otherwise amorphous matrix. These carbon clusters have predominantly sp3 bonding at 1100°C that gradually converts to predominantly sp 2 bonded carbon at higher temperatures, with average basal plane sizes of 20--25 A between 1100 in addition to 1600°C. The amorphous structure formed at temperatures below the crystallization temperature is unstable. It is seen from DSC that amorphous AHPCS-SiC undergoes two distinct exothermic events: a broad, irreversible, exotherm that corresponds to structural relaxation and chemical condensation and a second, much sharper, exotherm that corresponds to crystallization. Fracture toughness values measured on cold-pressed and infiltrated AHPCS-SiC samples were in the range of 1.4 to 1.67 MPam1/2. It appears that toughness increases with increasing heat treatment temperature. The Vickers hardness at 10 N was ca. 8.7 to 12.6 MPa. The Vickers hardness does not appear to vary significantly with the heat-treatment temperature.

Tuning three-dimensional collagen matrix stiffness independently of collagen concentration modulates endothelial cell behavior.

PubMed

Mason, Brooke N; Starchenko, Alina; Williams, Rebecca M; Bonassar, Lawrence J; Reinhart-King, Cynthia A

2013-01-01

Numerous studies have described the effects of matrix stiffening on cell behavior using two-dimensional synthetic surfaces; however, less is known about the effects of matrix stiffening on cells embedded in three-dimensional in vivo-like matrices. A primary limitation in investigating the effects of matrix stiffness in three dimensions is the lack of materials that can be tuned to control stiffness independently of matrix density. Here, we use collagen-based scaffolds where the mechanical properties are tuned using non-enzymatic glycation of the collagen in solution, prior to polymerization. Collagen solutions glycated prior to polymerization result in collagen gels with a threefold increase in compressive modulus without significant changes to the collagen architecture. Using these scaffolds, we show that endothelial cell spreading increases with matrix stiffness, as does the number and length of angiogenic sprouts and the overall spheroid outgrowth. Differences in sprout length are maintained even when the receptor for advanced glycation end products is inhibited. Our results demonstrate the ability to de-couple matrix stiffness from matrix density and structure in collagen gels, and that increased matrix stiffness results in increased sprouting and outgrowth. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Tracking Debris Shed by a Space-Shuttle Launch Vehicle

NASA Technical Reports Server (NTRS)

Stuart, Phillip C.; Rogers, Stuart E.

2009-01-01

The DEBRIS software predicts the trajectories of debris particles shed by a space-shuttle launch vehicle during ascent, to aid in assessing potential harm to the space-shuttle orbiter and crew. The user specifies the location of release and other initial conditions for a debris particle. DEBRIS tracks the particle within an overset grid system by means of a computational fluid dynamics (CFD) simulation of the local flow field and a ballistic simulation that takes account of the mass of the particle and its aerodynamic properties in the flow field. The computed particle trajectory is stored in a file to be post-processed by other software for viewing and analyzing the trajectory. DEBRIS supplants a prior debris tracking code that took .15 minutes to calculate a single particle trajectory: DEBRIS can calculate 1,000 trajectories in .20 seconds on a desktop computer. Other improvements over the prior code include adaptive time-stepping to ensure accuracy, forcing at least one step per grid cell to ensure resolution of all CFD-resolved flow features, ability to simulate rebound of debris from surfaces, extensive error checking, a builtin suite of test cases, and dynamic allocation of memory.

Theoretical studies of growth processes and electronic properties of nanostructures on surfaces

NASA Astrophysics Data System (ADS)

Mo, Yina

Low dimensional nanostructures have been of particular interest because of their potential applications in both theoretical studies and industrial use. Although great efforts have been put into obtaining better understanding of the formation and properties of these materials, many questions still remain unanswered. This thesis work has focused on theoretical studies of (1) the growth processes of magnetic nanowires on transition-metal surfaces, (2) the dynamics of pentacene thin-film growth and island structures on inert surfaces, and (3) our proposal of a new type of semiconducting nanotube. In the first study, we elucidated a novel and intriguing kinetic pathway for the formation of Fe nanowires on the upper edge of a monatomic-layer-high step on Cu(111) using first-principles calculations. The identification of a hidden fundamental Fe basal line within the Cu steps prior to the formation of the apparent upper step edge Fe wire produces a totally different view of step-decorating wire structures and offers new possibilities for the study of the properties of these wires. Subsequent experiments with scanning tunneling microscopy unambiguously established the essential role of embedded Fe atoms as precursors to monatomic wire growth. A more general study of adatom behavior near transition-metal step edges illustrated a systematic trend in the adatom energetics and kinetics, resulted from the electronic interactions between the adatom and the surfaces. This work opens the possibility of controlled manufacturing of one-dimensional nanowires. In the second study, we investigated pentacene thin-films on H-diamond, H-silica and OH-silica surfaces via force field molecular dynamics simulations. Pentacene island structures on these surfaces were identified and found to have a 90-degree rotation relative to the structure proposed by some experimental groups. Our work may facilitate the design and control of experimental pentacene thin-film growth, and thus the development of organic thin-film transistors. Finally, in our third study, we proposed a new type of structurally simple and energetically stable cyanide transition metal nanotube, based on the planar structure of M(CN)2, (M = Ni, Pd, Pt). These nanotubes have semiconducting character with large band gaps (2--3 eV), which are insensitive to the chirality and diameter. We have investigated the energetic, electronic, and mechanical properties of these materials in both planar and tubular forms through first-principles density functional calculations. These calculations reveal interesting multi-center bonding features that should lead to preferential growth of tubes of a particular chirality. The unique features of these nanotubes should make them capable of being mass-produced, which is one of the most significant shortcomings of semiconducting carbon nanotubes.

78 FR 70934 - Trespassing on DOE Property: Kansas City Plant Facilities

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-27

..., National Nuclear Security Administration, Kirtland Operations operating area. The facilities are described...). Addition of the Kirtland Operations operating area property does not terminate the prior Kansas City Plant...

Gradient-based reliability maps for ACM-based segmentation of hippocampus.

PubMed

Zarpalas, Dimitrios; Gkontra, Polyxeni; Daras, Petros; Maglaveras, Nicos

2014-04-01

Automatic segmentation of deep brain structures, such as the hippocampus (HC), in MR images has attracted considerable scientific attention due to the widespread use of MRI and to the principal role of some structures in various mental disorders. In this literature, there exists a substantial amount of work relying on deformable models incorporating prior knowledge about structures' anatomy and shape information. However, shape priors capture global shape characteristics and thus fail to model boundaries of varying properties; HC boundaries present rich, poor, and missing gradient regions. On top of that, shape prior knowledge is blended with image information in the evolution process, through global weighting of the two terms, again neglecting the spatially varying boundary properties, causing segmentation faults. An innovative method is hereby presented that aims to achieve highly accurate HC segmentation in MR images, based on the modeling of boundary properties at each anatomical location and the inclusion of appropriate image information for each of those, within an active contour model framework. Hence, blending of image information and prior knowledge is based on a local weighting map, which mixes gradient information, regional and whole brain statistical information with a multi-atlas-based spatial distribution map of the structure's labels. Experimental results on three different datasets demonstrate the efficacy and accuracy of the proposed method.

45 CFR 2541.30 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

.... Equipment. The term equipment means tangible, nonexpendable, personal property having a useful life of more... system under which payments are made for construction work according to the percentage of completion of the work, rather than to the grantee's cost incurred. Prior approval. The term prior approval means...

Electrically switchable polymer liquid crystal and polymer birefringent flake in fluid host systems and optical devices utilizing same

DOEpatents

Marshall, Kenneth L.; Kosc, Tanya Z.; Jacobs, Stephen D.; Faris, Sadeg M.; Li, Le

2003-12-16

Flakes or platelets of polymer liquid crystals (PLC) or other birefringent polymers (BP) suspended in a fluid host medium constitute a system that can function as the active element in an electrically switchable optical device when the suspension is either contained between a pair of rigid substrates bearing transparent conductive coatings or dispersed as microcapsules within the body of a flexible host polymer. Optical properties of these flake materials include large effective optical path length, different polarization states and high angular sensitivity in their selective reflection or birefringence. The flakes or platelets of these devices need only a 3-20.degree. rotation about the normal to the cell surface to achieve switching characteristics obtainable with prior devices using particle rotation or translation.

CO2 laser cutting of ultra thin (75 μm) glass based rigid optical solar reflector (OSR) for spacecraft application

NASA Astrophysics Data System (ADS)

Mishra, Shubham; Sridhara, N.; Mitra, Avijit; Yougandar, B.; Dash, Sarat Kumar; Agarwal, Sanjay; Dey, Arjun

2017-03-01

Present study reports for the first time laser cutting of multilayered coatings on both side of ultra thin (i.e., 75 μm) glass substrate based rigid optical solar reflector (OSR) for spacecraft thermal control application. The optimization of cutting parameters was carried out as a function of laser power, cutting speed and number of cutting passes and their effect on cutting edge quality. Systematic and in-detail microstructural characterizations were carried out by optical and scanning electron microscopy techniques to study the laser affected zone and cutting edge quality. Sheet resistance and water contact angle experiments were also conducted locally both prior and after laser cut to investigate the changes of electrical and surface properties, if any.

An Exploration of Geometric and Electronic Effects in Metal Nanoparticle Catalysts

NASA Astrophysics Data System (ADS)

Childers, David

The goal of this thesis is to investigate the influence geometric and electronic effects on metal nanoparticle catalysis. There are three main methods which alter a catalyst's properties: changing support material, changing nanoparticle size and alloying a second metal. This work will focus on the latter two methods using Pt-group metals and alloys. Platinum and palladium were chosen as the active metals due to a large amount of industry significance and prior literature to draw upon. Neopentane conversion and propane dehydrogenation were the two probe reactions used to evaluate these catalysts mainly due to their relative simplicity and ease of operation on a laboratory scale. The effect of particle size was studied with Pt and Pd monometallic catalysts using neopentane hydrogenolysis/isomerization as the probe reaction. Particle size studies have been done previously using this reaction so there is literature data to compare this study's results. This data will also be used as comparison for the bimetallic studies conducted later so that particle size effects can be accounted for when attempting to determine the effect of alloying a second metal. Bimetallic catalysts have several different possible structures depending on a number of factors from the identity of the two metals to the synthesis procedure. Homogeneous, core-shell and intermetallic alloys are the three structures evaluated in this work. Determining the surface composition of a homogeneous alloy can be difficult especially if both metals adsorb CO. PtPd homogeneous alloys were used to evaluate the ability of EXAFS to give information about surface composition using CO adsorption. These catalysts were also tested using neopentane conversion to evaluate changes in catalytic performance. Core-shell catalysts can also exhibit unique properties although it is not clear whether the identity of the core metal is relevant or if surface changes are most important to changing catalytic behavior. PdAu catalysts were synthesized with varying Pd loadings to determine if the Au-rich core would continue to influence neopentane conversion performance with increasing Pd layers on the surface of the nanoparticle. Finally, intermetallic alloys have produced some very interesting literature results and can drastically alter catalyst surface structure. PdZn showed the potential to improve neopentane isomerization selectivity past that of Pt based on calculated electronic properties. Two PdZn catalysts with different loadings were synthesized to evaluate the electronic and geometric effects using both neopentane conversion and propane dehydrogenation.

41 CFR 101-27.203 - Program objectives.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Conduct inventory management analyses to determine if shelf-life stocks are expected to be utilized prior... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Program objectives. 101-27.203 Section 101-27.203 Public Contracts and Property Management Federal Property Management...

38 CFR 36.4210 - Joint loans.

Code of Federal Regulations, 2010 CFR

2010-07-01

... acquire an undivided interest in the property to be purchased or who will otherwise share in the proceeds... of property shall not require prior approval or preclude the issuance of a guaranty based upon the...

Recruiting physisorbed water in surface polymerization for bio-inspired materials of tunable hydrophobicity

DOE PAGES

Oyola-Reynoso, S.; Tevis, I. D.; Chen, J.; ...

2016-08-18

Here, chemical grafting has been widely used to modify the surface properties of materials, especially surface energy for controlled wetting, because of the resilience of such coatings/modifications. Reagents with multiple reactive sites have been used with the expectation that a monolayer will form. The step-growth polymerization mechanism, however, suggests the possibility of gel formation for hydrolyzable moieties in the presence of physisorbed water. In this report, we demonstrated that using alkyltrichlorosilanes (trivalent [i.e., 3 reactive sites]) in the surface modification of a cellulosic material (paper) does not yield a monolayer but rather gives surface-bound particles. We infer that the presencemore » of physisorbed (surface-bound) water allows for polymerization (or oligomerization) of the silane prior to its attachment on the surface. Surface energy mismatch between the hydrophobic tails of the growing polymer and any unreacted bound water leads to the assembly of the polymerizing material into spherical particles to minimize surface tension. By varying paper grammage (16.2–201.4 g m –2), we varied the accessible surface area and thus the amount of surface-adsorbed water, allowing us to control the ratio of the silane to the bound water. Using this approach, polymeric particles were formed on the surface of cellulose fibers ranging from ~70 nm to a film. The hydrophobicity of the surface, as determined by water contact angles, correlates with particle sizes (p < 0.001, Student's t-test), and, hence, the hydrophobicity can be tuned (contact angle between 94° and 149°). Using a model structure of a house, we demonstrated that as a result of this modification, paper-based houses can be rendered self-cleaning or tolerant to surface running water. In another application, we demonstrated that the felicitous choice of architectural design allows for the hydrophobic paper to be used for water harvesting.« less

Postural control as a function of time-of-day: influence of a prior strenuous running exercise or demanding sustained-attention task

PubMed Central

2013-01-01

Background The current experiment investigated the impact of two potential confounding variables on the postural balance in young participants: the induced-experimental activity prior to the static postural measurements and the well-documented time-of-day effects. We mainly hypothesized that an exhaustive exercise and a high attention-demanding task should result in alterations of postural control. Methods Ten participants performed three experimental sessions (differentiated by the activity – none, cognitive or physical – prior of the assessment of postural stability), separated by one day at least. Each session included postural balance assessments around 8 a.m., 12.00 p.m. and 5 p.m. ± 30 min. The physical and cognitive activities were performed only before the 12 o’clock assessment. The postural tests consisted of four conditions of quiet stance: stance on a firm surface with eyes open; stance on a firm surface with eyes closed; stance on a foam surface with eyes open and stance on a foam surface with eyes closed. Postural performance was assessed by various center of pressure (COP) parameters. Results Overall, the COP findings indicated activity-related postural impairment, with an increase in body sway in the most difficult conditions (with foam surface), especially when postural measurements are recorded just after the running exercise (physical session) or the psychomotor vigilance test (cognitive session). Conclusions Even if no specific influence of time-of-day on static postural control is demonstrated, our results clearly suggest that the activities prior to balance tests could be a potential confounding variable to be taken into account and controlled when assessing clinical postural balance. PMID:23452958

Cardiovascular System during the Post Partum State in Women with a History of Preeclampsia

PubMed Central

Evans, Caroline S.; Gooch, Linda; Flotta, Deborah; Lykins, David; Powers, Robert W.; Landsittel, Douglas; Roberts, James M.; Shroff, Sanjeev G.

2011-01-01

Hypothesis In subjects with previous preeclampsia, differences in cardiovascular and/or blood biochemical parameters are present in the non-pregnant state and that a simultaneous assessment of multiple derived indices better differentiates between women with or without prior preeclampsia. We examined 18 prior preeclamptic and 50 prior uncomplicated pregnancies, ~16 months post partum. Cardiovascular assessment included: (1) systemic hemodynamics and mechanics (Doppler echocardiography, tonometry, oscillometric sphygmomanometry) (2) endothelial function (plethysmography) (3) left ventricular properties (echocardiography), and (4) blood biochemical analyses. Compared to women with prior uncomplicated pregnancies, prior preeclamptics had higher mean (80±1 vs. 86±3 mmHg, P=0.04) and diastolic (64±1 vs. 68±2 mmHg; P=0.04) pressures and total vascular resistance (1562±37 vs. 1784±114 dyne•s/cm5; P=0.03). Systolic blood pressure, arterial compliance, and left ventricular properties were not different. While heart-to-femoral pulse wave velocity was not different, heart-to-brachial pulse wave velocity tended to be faster in prior preeclamptics (374±8 vs. 404±20 cm/s; P=0.06). Stress-induced increase in forearm blood flow was less in prior preeclamptics (245±21% vs. 136±22%; P=0.01), indicating impaired endothelial function. No significant differences were observed in markers of endothelial activation, dyslipidemia, or oxidative stress; prior preeclamptics tended to have higher glucose level (58.7±1.9 vs. 95±5.2 mg/dl; P=0.06). Logistic regression analysis indicated that a simultaneous evaluation of multiple derived indices better discriminated between the two groups. The differences in the prior preeclamptic group are in directions known to be associated with greater cardiovascular disease risk later in life. PMID:21606389

24 CFR 201.20 - Property improvement loan eligibility.

Code of Federal Regulations, 2010 CFR

2010-04-01

... jurisdiction over the fire safety requirements of health care facilities prior to making application for a loan... property improvement loan (other than a manufactured home improvement loan), the borrower shall have at... property. (2) To be eligible for a manufactured home improvement loan, the borrower shall have at least a...

48 CFR 52.245-9 - Use and Charges.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the property to its condition prior to rental (less normal wear and tear). (b) Use of Government... property to its pre-rental condition (less normal wear and tear), or both. (h) Unauthorized use. The...

Comparative multibody dynamics analysis of falls from playground climbing frames.

PubMed

Forero Rueda, M A; Gilchrist, M D

2009-10-30

This paper shows the utility of multibody dynamics in evaluating changes in injury related parameters of the head and lower limbs of children following falls from playground climbing frames. A particular fall case was used as a starting point to analyze the influence of surface properties, posture of the body at impact, and intermediate collisions against the climbing frame before impacting the ground. Simulations were made using the 6-year-old pedestrian MADYMO rigid body model and scaled head contact characteristics. Energy absorbing surfaces were shown to reduce injury severity parameters by up to 30-80% of those of rigid surfaces, depending on impact posture and surface. Collisions against components of a climbing frame during a fall can increase injury severity of the final impact of the head with the ground by more than 90%. Negligible changes are associated with lower limb injury risks when different surfacing materials are used. Computer reconstructions of actual falls that are intended to quantify the severity of physical injuries rely on accurate knowledge of initial conditions prior to falling, intermediate kinematics of the fall and the orientation of the body when it impacts against the ground. Multibody modelling proved to be a valuable tool to analyze the quality of eyewitness information and analyze the relative injury risk associated with changes in components influencing fall injuries from playground climbing frames. Such simulations can also support forensic investigations by evaluating alternative hypotheses for the sequence of kinematic motion of falls which result in known injuries.

The Role of Glottal Surface Adhesion on Vocal Folds Biomechanics

PubMed Central

Bhattacharya, Pinaki; Siegmund, Thomas

2014-01-01

The airway surface liquid (ASL) is a very thin mucus layer and covers the vocal fold (VF) surface. Adhesion mediated by the ASL occurs during phonation as the VFs separate after collision. Such adhesion is hypothesized to determine voice quality and health. However, biomechanical insights into the adhesive processes during VF oscillation are lacking. Here, a computational study is reported on self-sustained VF vibration involving contact and adhesion. The VF structural model and the glottal airflow are considered fully three-dimensional. The mechanical behavior of the ASL is described through a constitutive traction–separation law where mucosal cohesive strength, cohesive energy and rupture length enter. Cohesive energy values considered are bound below by the cohesive energy of water at standard temperature and pressure. Cohesive strength values considered are bound above by prior reported data on the adhesive strength of mucosal surface of rat small intestine. This model introduces a mechanical length scale into the analysis. The sensitivity of various aspects of VF dynamics such as flow-declination rate, VF separation under adhesive condition and formation of multiple local fluid bridges is determined in relation to specific ASL adhesive properties. It is found that for the ASL considered here, the characteristics of the VF separation process are of debond type. Instabilities lead to the breakup of the bond area into several smaller bond patches. Such finding is consistent with in-vivo observations. PMID:25034504

Capturing latent fingerprints from metallic painted surfaces using UV-VIS spectroscope

NASA Astrophysics Data System (ADS)

Makrushin, Andrey; Scheidat, Tobias; Vielhauer, Claus

2015-03-01

In digital crime scene forensics, contactless non-destructive detection and acquisition of latent fingerprints by means of optical devices such as a high-resolution digital camera, confocal microscope, or chromatic white-light sensor is the initial step prior to destructive chemical development. The applicability of an optical sensor to digitalize latent fingerprints primarily depends on reflection properties of a substrate. Metallic painted surfaces, for instance, pose a problem for conventional sensors which make use of visible light. Since metallic paint is a semi-transparent layer on top of the surface, visible light penetrates it and is reflected off of the metallic flakes randomly disposed in the paint. Fingerprint residues do not impede light beams making ridges invisible. Latent fingerprints can be revealed, however, using ultraviolet light which does not penetrate the paint. We apply a UV-VIS spectroscope that is capable of capturing images within the range from 163 to 844 nm using 2048 discrete levels. We empirically show that latent fingerprints left behind on metallic painted surfaces become clearly visible within the range from 205 to 385 nm. Our proposed streakiness score feature determining the proportion of a ridge-valley pattern in an image is applied for automatic assessment of a fingerprint's visibility and distinguishing between fingerprint and empty regions. The experiments are carried out with 100 fingerprint and 100 non-fingerprint samples.

Progress in Understanding the Pre-Earthquake Associated Events by Analyzing IR Satellite Data

NASA Technical Reports Server (NTRS)

Ouzounov, Dimitar; Taylor, Patrick; Bryant, Nevin

2004-01-01

We present latest result in understanding the potential relationship between tectonic stress, electro-chemical and thermodynamic processes in the Earths crust and atmosphere with an increase in IR flux as a potential signature of electromagnetic (EM) phenomena that are related to earthquake activity, either pre-, co- or post seismic. Thermal infra-red (TIR) surveys performed by the polar orbiting (NOAA/AVHRR MODIS) and geosynchronous weather satellites (GOES, METEOSAT) gave an indication of the appearance (from days to weeks before the event) of "anomalous" space-time TIR transients that are associated with the location (epicenter and local tectonic structures) and time of a number of major earthquakes with M>5 and focal depths less than 50km. We analyzed broad category of associated pre-earthquake events, which provided evidence for changes in surface temperature, surface latent heat flux, chlorophyll concentrations, soil moisture, brightness temperature, emissivity of surface, water vapour in the atmosphere prior to the earthquakes occurred in Algeria, India, Iran, Italy, Mexico and Japan. The cause of such anomalies has been mainly related to the change of near-surface thermal properties due to complex lithosphere-hydrosphere-atmospheric interactions. As final results we present examples from the most recent (2000-2004) worldwide strong earthquakes and the techniques used to capture the tracks of EM emission mid-IR anomalies and a methodology for practical future use of such phenomena in the early warning systems.

Phosphonate-anchored monolayers for antibody binding to magnetic nanoparticles.

PubMed

Benbenishty-Shamir, Helly; Gilert, Roni; Gotman, Irena; Gutmanas, Elazar Y; Sukenik, Chaim N

2011-10-04

Targeted delivery of magnetic iron oxide nanoparticles (IONPs) to a specific tissue can be achieved by conjugation with particular biological ligands on an appropriately functionalized IONP surface. To take best advantage of the unique magnetic properties of IONPs and to maximize their blood half-life, thin, strongly bonded, functionalized coatings are required. The work reported herein demonstrates the successful application of phosphonate-anchored self-assembled monolayers (SAMs) as ultrathin coatings for such particles. It also describes a new chemical approach to the anchoring of antibodies on the surface of SAM-coated IONPs (using nucleophilic aromatic substitution). This anchoring strategy results in stable, nonhydrolyzable, covalent attachment and allows the reactivity of the particles toward antibody binding to be activated in situ, such that prior to the activation the modified surface is stable for long-term storage. While the SAMs do not have the well-packed crystallinity of other such monolayers, their structure was studied using smooth model substrates based on an iron oxide layer on a double-side polished silicon wafer. In this way, atomic force microscopy, ellipsometry, and contact angle goniometry (tools that could not be applied to the nanoparticles' surfaces) could contribute to the determination of their monomolecular thickness and uniformity. Finally, the successful conjugation of IgG antibodies to the SAM-coated IONPs such that the antibodies retain their biological activity is verified by their complexation to a secondary fluorescent antibody. © 2011 American Chemical Society

Polyimide/Carbon Nanotube Composite Films for Electrostatic Charge Mitigation

NASA Technical Reports Server (NTRS)

Smith, Joseph G., Jr.; Delozier, Donavon M.; Connell, John W.; Watson, Kent A.

2004-01-01

Low color, space environmentally durable polymeric films with sufficient electrical conductivity to mitigate electrostatic charge (ESC) build-up have potential applications on large, deployable, ultra-light weight Gossamer spacecraft as thin film membranes on antennas, solar sails, thermal/optical coatings, multi-layer insulation blankets, etc.. The challenge has been to develop a method to impart robust electrical conductivity into these materials without increasing solar absorptivity (alpha ) or decreasing optical transparency or film flexibility. Since these spacecraft will require significant compaction prior to launch, the film portion of the spacecraft will require folding. The state-of-the-art clear, conductive coating (e.g. indium-tin-oxide, ITO) is brittle and cannot tolerate folding. In this report, doping a polymer with single-walled carbon nanotubes (SWNTs) using two different methods afforded materials with good flexibility and surface conductivities in the range sufficient for ESC mitigation. A coating method afforded materials with minimal effects on the mechanical, optical, and thermo-optical properties as compared to dispersal of SWNTs in the matrix. The chemistry and physical properties of these nanocomposites are discussed.

Caveolae provide a specialized membrane environment for respiratory syncytial virus assembly

PubMed Central

Nguyen, Tra Huong; Leong, Daniel; Ravi, Laxmi Iyer; Tan, Boon Huan; Sandin, Sara; Sugrue, Richard J.

2017-01-01

ABSTRACT Respiratory syncytial virus (RSV) is an enveloped virus that assembles into filamentous virus particles on the surface of infected cells. Morphogenesis of RSV is dependent upon cholesterol-rich (lipid raft) membrane microdomains, but the specific role of individual raft molecules in RSV assembly is not well defined. Here, we show that RSV morphogenesis occurs within caveolar membranes and that both caveolin-1 and cavin-1 (also known as PTRF), the two major structural and functional components of caveolae, are actively recruited to and incorporated into the RSV envelope. The recruitment of caveolae occurred just prior to the initiation of RSV filament assembly, and was dependent upon an intact actin network as well as a direct physical interaction between caveolin-1 and the viral G protein. Moreover, cavin-1 protein levels were significantly increased in RSV-infected cells, leading to a virus-induced change in the stoichiometry and biophysical properties of the caveolar coat complex. Our data indicate that RSV exploits caveolae for its assembly, and we propose that the incorporation of caveolae into the virus contributes to defining the biological properties of the RSV envelope. PMID:28154158

Self-aligning concave relativistic plasma mirror with adjustable focus

DOE PAGES

Tsai, Hai-En; Arefiev, Alexey V.; Shaw, Joseph M.; ...

2017-01-04

We report an experimental-computational study of the optical properties of plasma mirrors (PMs) at the incident laser frequency when irradiated directly at relativistic intensity (10 180<10 19W/cm 2) by near-normally incident (4°), high-contrast, 30 fs, 800 nm laser pulses. We find that such relativistic PMs are highly reflective (0.6–0.8) and focus a significant fraction of reflected light to intensity as large as ~10I0 at distance f as small as ~25 μm from the PM, provided that pre-pulses do not exceed 10 14 W/cm 2 prior to ~20 ps before arrival of the main pulse peak. Particle-in-cell simulations show that focusingmore » results from denting of the reflecting surface by light pressure combined with relativistic transparency and that reflectivity and f can be adjusted by controlling pre-plasma length L over the range 0.5 ≲L ≲ 3 μm. Pump-probe reflectivity measurements show that the PM's focusing properties evolve on a ps time scale.« less

Laser vibrometry in the quality control of the break of tanned leather

NASA Astrophysics Data System (ADS)

Preciado, J. Sanchez; Lopez, C. Perez; Hernandez-Montes, M. del Socorro; Torre-Ibarra, M. de la; Moreno, J. M. Flores; Ruiz, C. Tavera; Mendoza Santoyo, F.; Galan, M.

2018-05-01

Tanning industry treats hides and the skin of animals for their use in products such as clothes, furniture and car's interiors. The worth of leather is highly affected by defects that may appear prior or during the tanning process. Break, which refers to the wrinkling of the grain surface of leather, is one of the main issues because it affects not only the visual appearance of leather, but also its mechanical properties. The standardized method to classify the break pattern is done by bending the leather with the hand and comparing visually the resulting wrinkles that appear with a reference pattern, which makes the classification subjective and limits the evaluation to small areas. Laser vibrometry is an optical technique that has been applied in vibrational and modal analysis, which are methodologies used to obtain the mechanical properties of materials. This work demonstrates the use of a single-point vibrometer as a noncontact and nondestructive optical method to discriminate among five break levels, which could increase the effectiveness of leather classification for quality control in the tanning industry.

Carbon nanotube-poly(methyl methacrylate) hybrid films: preparation using diazonium salt chemistry and mechanical properties.

PubMed

Mammeri, Fayna; Teyssandier, Joan; Darche-Dugaret, Clément; Debacker, Sabine; Le Bourhis, Eric; Chehimi, Mohamed Mehdi

2014-11-01

The poor miscibility of carbon nanotubes (CNTs) in common organic solvents and organic monomers requires their modification by suitable functional (reactive or not) groups prior to their incorporation in thermoplastic polymers. Dispersion behavior of carbon nanotubes and mechanical properties of various CNT-poly(methylmethacrylate) (PMMA) nanocomposites were investigated. We studied the influence of the surface chemistry through the use of diazonium salts as an elegant and environmentally friendly platform to provide a suitable sidewall functionalization by methyl methacrylate functions. We used either a molecular size functional group through the grafting of methacryloxypropyltrimethoxysilane or a macromolecular size one, consisting in PMMA brushes grown by SI-ATRP in order to study the influence of the length of methacrylate function on the dispersion of CNT in PMMA. The hardness and the elastic indentation modulus of all hybrid films were obtained through nanoindentation measurements and found to increase, using ATRP-modified CNTs, suggesting a better dispersion of CNTs in PMMA due to optimal inorganic-organic interactions promoted by the short chains of PMMA. Copyright © 2014 Elsevier Inc. All rights reserved.

Self-aligning concave relativistic plasma mirror with adjustable focus

NASA Astrophysics Data System (ADS)

Tsai, Hai-En; Arefiev, Alexey V.; Shaw, Joseph M.; Stark, David J.; Wang, Xiaoming; Zgadzaj, Rafal; Downer, M. C.

2017-01-01

We report an experimental-computational study of the optical properties of plasma mirrors (PMs) at the incident laser frequency when irradiated directly at relativistic intensity ( 10 18 < I 0 < 10 19 W / cm 2 ) by near-normally incident ( 4 ° ), high-contrast, 30 fs, 800 nm laser pulses. We find that such relativistic PMs are highly reflective ( 0.6 - 0.8 ) and focus a significant fraction of reflected light to intensity as large as ˜ 10 I 0 at distance f as small as ˜ 25 μ m from the PM, provided that pre-pulses do not exceed 1014 W/cm2 prior to ˜ 20 ps before arrival of the main pulse peak. Particle-in-cell simulations show that focusing results from denting of the reflecting surface by light pressure combined with relativistic transparency and that reflectivity and f can be adjusted by controlling pre-plasma length L over the range 0.5 ≲ L ≲ 3 μ m. Pump-probe reflectivity measurements show that the PM's focusing properties evolve on a ps time scale.

7 CFR 1955.145 - Land acquisition to effect sale.

Code of Federal Regulations, 2010 CFR

2010-01-01

... organization-type loans, prior approval must be obtained from the appropriate Assistant Administrator prior to... and where it is economically feasible to relocate the structure thereby making it a program property... structure if economically feasible. The remaining NP parcel of land will be sold for its market value. (b...

Military Base Closures: Updated Status of Prior Base Realignments and Closures

EPA Pesticide Factsheets

As the Department of Defense (DOD) prepares for the 2005 base realignment and closure (BRAC) round, questions continue to be raised about the transfer and environmental cleanup of unneeded property arising from the prior four BRAC rounds and their impact on cost and savings and on local economies.

VizieR Online Data Catalog: Parameters of atmospheres of white dwarfs (Mortlock+, 2009)

NASA Astrophysics Data System (ADS)

Mortlock, D. J.; Peiris, H. V.; Ivezic, Z.

2010-03-01

It is possible to reliably identify white dwarfs (WDs) without recourse to spectra, instead using photometric and astrometric measurements to distinguish them from main-sequence stars and quasars. WDs' colours can also be used to infer their intrinsic properties (effective temperature, surface gravity, etc.), but the results obtained must be interpreted with care. The difficulties stem from the existence of a solid angle degeneracy, as revealed by a full exploration of the likelihood, although this can be masked if a simple best-fitting approach is used. Conversely, this degeneracy can be broken if a Bayesian approach is adopted, as it is then possible to utilize the prior information on the surface gravities of WDs implied by spectroscopic fitting. The benefits of such an approach are particularly strong when applied to outliers, such as the candidate halo and ultracool WDs identified by Vidrih et al. A reanalysis of these samples confirms their results for the latter sample, but suggests that most of the halo candidates are thick-disc WDs in the tails of the photometric noise distribution. (7 data files).

Response surface methodology for studying the effect of processing conditions on some nutritional and textural properties of bambara groundnuts (Voandzei subterranea) during canning.

PubMed

Afoakwa, Emmanuel Ohene; Budu, Agnes Simpson; Merson, Alan Bullock

2007-06-01

The response surface methodology and central composite rotatable design for K=3 was used to study the combined effect of blanching, soaking and sodium hexametaphosphate salt concentration on moisture, ash, leached solids, phytates, tannins and hardness of bambara groundnut during canning. Regression models were developed to predict the effects of the processing parameters on the studied indices. Significant interactions were observed between all the factors with high regression coefficients (64.4-82.6%). Blanching and soaking of the seeds prior to canning led to increases in moisture content and leached solids, while significant decreases were observed for phytates, tannins and hardness of the canned bambara groundnuts. Increasing the concentration of sodium salt added during soaking caused significant (P

Graphene/graphene oxide and their derivatives in the separation/isolation and preconcentration of protein species: A review.

PubMed

Chen, Xuwei; Hai, Xin; Wang, Jianhua

2016-05-30

The distinctive/unique electrical, chemical and optical properties make graphene/graphene oxide-based materials popular in the field of analytical chemistry. Its large surface offers excellent capacity to anchor target analyte, making it an powerful sorbent in the adsorption and preconcentration of trace level analyte of interest in the field of sample preparation. The large delocalized π-electron system of graphene framework provides strong affinity to species containing aromatic rings, such as proteins, and the abundant active sites on its surface offers the chance to modulate adsorption tendency towards specific protein via functional modification/decoration. This review provides an overview of the current research on graphene/graphene oxide-based materials as attractive and powerful adsorption media in the separation/isolation and preconcentration of protein species from biological sample matrixes. These practices are aiming at providing protein sample of high purity for further investigations and applications, or to achieve certain extent of enrichment prior to quantitative assay. In addition, the challenges and future perspectives in the related research fields have been discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

Co removal and phase transformations during high power diode laser irradiation of cemented carbide

NASA Astrophysics Data System (ADS)

Barletta, M.; Rubino, G.; Gisario, A.

2011-02-01

The use of a continuous wave-high power diode laser for removing surface Co-binder from Co-cemented tungsten carbide (WC-Co (5.8 wt%.)) hardmetal slabs was investigated. Combined scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction analyses were performed in order to study the phase transformations and micro-structural modifications of the WC-Co substrates occurring during and after laser irradiation. The micro-structure of the WC-Co progressively transforms as energy density increased, exhibiting stronger removal of Co and WC grain growth. At very high energy density, local melting of the WC grains with the formation of big agglomerates of interlaced grains is observed, and the crystalline structure of the irradiated substrate shows the presence of a brittle ternary eutectic phase of W, Co and C (often referred to as the η-phase). The latter can be detrimental to the mechanical properties of WC-Co. Therefore, the proper adjustment of the laser processing parameters plays a crucial role in surface treatments of WC-Co substrates prior to post-processing like diamond deposition.

Understanding the Potential Toxic Properties of Lunar Dust

NASA Technical Reports Server (NTRS)

2009-01-01

Lunar dust causes a variety of problems for spacecraft. It can obscure vision, clog equipment, cause seal failures and abrade surfaces. Additionally, lunar dust is potentially toxic and therefore hazardous to astronauts. Lunar dust can be activated by meteorites, UV radiation and elements of solar wind and, if inhaled, could produce reactive species in the lungs (freshly fractured quartz). Methods of lunar dust deactivation must be determined before new lunar missions. This requires knowledge of how to reactivate lunar dust on Earth - thus far crushing/grinding, UV activation and heating have been tested as activation methods. Grinding of lunar dust leads to the production of hydroxyl radicals in solution and increased dissolution of lunar simulant in buffers of different pH. Decreases in pH lead to increased lunar simulant leaching. Additionally, both ground and unground lunar simulant and unground quartz have been shown to promote the production of IL-6 and IL-8, pro-inflammatory cytokines, by alveolar epithelial cells. The results suggest the need for further studies on lunar dust and simulants prior to returning to the lunar surface.

Rapid Detection of Escherichia coli O157:H7 in Fresh Lettuce Based on Localized Surface Plasmon Resonance Combined with Immunomagnetic Separation.

PubMed

Lee, Nari; Choi, Sung-Wook; Chang, Hyun-Joo; Chun, Hyang Sook

2018-05-01

This study presents a method for rapid detection of Escherichia coli O157:H7 in fresh lettuce based on the properties of target separation and localized surface plasmon resonance of immunomagnetic nanoparticles. The multifunctional immunomagnetic nanoparticles enabling simultaneous separation and detection were prepared by synthesizing magnetic nanoparticles (ca. 10 nm in diameter) composed of an iron oxide (Fe 3 O 4 ) core and gold shell and then conjugating these nanoparticles with the anti- E. coli O157:H7 antibodies. The application of multifunctional immunomagnetic nanoparticles for detecting E. coli O157:H7 in a lettuce matrix allowed detection of the presence of <1 log CFU mL -1 without prior enrichment. In contrast, the detection limit of the conventional plating method was 2.74 log CFU mL -1 . The method, which requires no preenrichment, provides an alternative to conventional microbiological detection methods and can be used as a rapid screening tool for a large number of food samples.

New generation of magnetic and luminescent nanoparticles for in vivo real-time imaging

PubMed Central

Lacroix, Lise-Marie; Delpech, Fabien; Nayral, Céline; Lachaize, Sébastien; Chaudret, Bruno

2013-01-01

A new generation of optimized contrast agents is emerging, based on metallic nanoparticles (NPs) and semiconductor nanocrystals for, respectively, magnetic resonance imaging (MRI) and near-infrared (NIR) fluorescent imaging techniques. Compared with established contrast agents, such as iron oxide NPs or organic dyes, these NPs benefit from several advantages: their magnetic and optical properties can be tuned through size, shape and composition engineering, their efficiency can exceed by several orders of magnitude that of contrast agents clinically used, their surface can be modified to incorporate specific targeting agents and antifolding polymers to increase blood circulation time and tumour recognition, and they can possibly be integrated in complex architecture to yield multi-modal imaging agents. In this review, we will report the materials of choice based on the understanding of the basic physics of NIR and MRI techniques and their corresponding syntheses as NPs. Surface engineering, water transfer and specific targeting will be highlighted prior to their first use for in vivo real-time imaging. Highly efficient NPs that are safer and target specific are likely to enter clinical application in a near future. PMID:24427542

A Simple Method for Estimating Informative Node Age Priors for the Fossil Calibration of Molecular Divergence Time Analyses

PubMed Central

Nowak, Michael D.; Smith, Andrew B.; Simpson, Carl; Zwickl, Derrick J.

2013-01-01

Molecular divergence time analyses often rely on the age of fossil lineages to calibrate node age estimates. Most divergence time analyses are now performed in a Bayesian framework, where fossil calibrations are incorporated as parametric prior probabilities on node ages. It is widely accepted that an ideal parameterization of such node age prior probabilities should be based on a comprehensive analysis of the fossil record of the clade of interest, but there is currently no generally applicable approach for calculating such informative priors. We provide here a simple and easily implemented method that employs fossil data to estimate the likely amount of missing history prior to the oldest fossil occurrence of a clade, which can be used to fit an informative parametric prior probability distribution on a node age. Specifically, our method uses the extant diversity and the stratigraphic distribution of fossil lineages confidently assigned to a clade to fit a branching model of lineage diversification. Conditioning this on a simple model of fossil preservation, we estimate the likely amount of missing history prior to the oldest fossil occurrence of a clade. The likelihood surface of missing history can then be translated into a parametric prior probability distribution on the age of the clade of interest. We show that the method performs well with simulated fossil distribution data, but that the likelihood surface of missing history can at times be too complex for the distribution-fitting algorithm employed by our software tool. An empirical example of the application of our method is performed to estimate echinoid node ages. A simulation-based sensitivity analysis using the echinoid data set shows that node age prior distributions estimated under poor preservation rates are significantly less informative than those estimated under high preservation rates. PMID:23755303

26 CFR 1.1031(d)-1 - Property acquired upon a tax-free exchange.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 26 Internal Revenue 11 2013-04-01 2013-04-01 false Property acquired upon a tax-free exchange. 1... Property acquired upon a tax-free exchange. (a) If, in an exchange of property solely of the type described... provision of a prior revenue law, on account of the receipt of money in the transaction, the basis of the...

26 CFR 1.1031(d)-1 - Property acquired upon a tax-free exchange.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 26 Internal Revenue 11 2010-04-01 2010-04-01 true Property acquired upon a tax-free exchange. 1... upon a tax-free exchange. (a) If, in an exchange of property solely of the type described in section... prior revenue law, on account of the receipt of money in the transaction, the basis of the property...

26 CFR 1.1031(d)-1 - Property acquired upon a tax-free exchange.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 26 Internal Revenue 11 2014-04-01 2014-04-01 false Property acquired upon a tax-free exchange. 1... Property acquired upon a tax-free exchange. (a) If, in an exchange of property solely of the type described... provision of a prior revenue law, on account of the receipt of money in the transaction, the basis of the...

26 CFR 1.1031(d)-1 - Property acquired upon a tax-free exchange.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 26 Internal Revenue 11 2012-04-01 2012-04-01 false Property acquired upon a tax-free exchange. 1... Property acquired upon a tax-free exchange. (a) If, in an exchange of property solely of the type described... provision of a prior revenue law, on account of the receipt of money in the transaction, the basis of the...

26 CFR 1.1031(d)-1 - Property acquired upon a tax-free exchange.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 26 Internal Revenue 11 2011-04-01 2011-04-01 false Property acquired upon a tax-free exchange. 1... Property acquired upon a tax-free exchange. (a) If, in an exchange of property solely of the type described... provision of a prior revenue law, on account of the receipt of money in the transaction, the basis of the...

Influence of surface defects on the tensile strength of carbon fibers

NASA Astrophysics Data System (ADS)

Vautard, F.; Dentzer, J.; Nardin, M.; Schultz, J.; Defoort, B.

2014-12-01

The mechanical properties of carbon fibers, especially their tensile properties, are affected by internal and surface defects. In order to asses in what extent the generation of surface defects can result in a loss of the mechanical properties, non-surface treated carbon fibers were oxidized with three different surface treatment processes: electro-chemical oxidation, oxidation in nitric acid, and oxidation in oxygen plasma. Different surface topographies and surface chemistries were obtained, as well as different types and densities of surface defects. The density of surface defects was measured with both a physical approach (Raman spectroscopy) and a chemical approach (Active Surface Area). The tensile properties were evaluated by determining the Weibull modulus and the scale parameter of each reference, after measuring the tensile strength for four different gauge lengths. A relationship between the tensile properties and the nature and density of surface defects was noticed, as large defects largely control the value of the tensile strength. When optimized, some oxidation surface treatment processes can generate surface functional groups as well as an increase of the mechanical properties of the fibers, because of the removal of the contamination layer of pyrolytic carbon generated during the carbonization of the polyacrylonitrile precursor. Oxidation in oxygen plasma revealed to be a promising technology for alternative surface treatment processes, as high levels of functionalization were achieved and a slight improvement of the mechanical properties was obtained too.

Super-Eddington stellar winds driven by near-surface energy deposition

NASA Astrophysics Data System (ADS)

Quataert, Eliot; Fernández, Rodrigo; Kasen, Daniel; Klion, Hannah; Paxton, Bill

2016-05-01

We develop analytic and numerical models of the properties of super-Eddington stellar winds, motivated by phases in stellar evolution when super-Eddington energy deposition (via, e.g. unstable fusion, wave heating, or a binary companion) heats a region near the stellar surface. This appears to occur in the giant eruptions of luminous blue variables (LBVs), Type IIn supernovae progenitors, classical novae, and X-ray bursts. We show that when the wind kinetic power exceeds Eddington, the photons are trapped and behave like a fluid. Convection does not play a significant role in the wind energy transport. The wind properties depend on the ratio of a characteristic speed in the problem v_crit˜ (dot{E} G)^{1/5} (where dot{E} is the heating rate) to the stellar escape speed near the heating region vesc(rh). For vcrit ≳ vesc(rh), the wind kinetic power at large radii dot{E}_w ˜ dot{E}. For vcrit ≲ vesc(rh), most of the energy is used to unbind the wind material and thus dot{E}_w ≲ dot{E}. Multidimensional hydrodynamic simulations without radiation diffusion using FLASH and one-dimensional hydrodynamic simulations with radiation diffusion using MESA are in good agreement with the analytic predictions. The photon luminosity from the wind is itself super-Eddington but in many cases the photon luminosity is likely dominated by `internal shocks' in the wind. We discuss the application of our models to eruptive mass-loss from massive stars and argue that the wind models described here can account for the broad properties of LBV outflows and the enhanced mass-loss in the years prior to Type IIn core-collapse supernovae.

Effect of liquid epoxidized natural rubber (LENR) on mechanical properties and morphology of natural rubber/high density polyethylene/mengkuang fiber (NR/HDPE/MK) bio-composite

NASA Astrophysics Data System (ADS)

Piah, Mohd Razi Mat; Baharum, Azizah

2016-11-01

The use of mengkuang fiber (MK) fibers in NR/HDPE (40/60) blend was studied via surface modification of fiber. The MK fiber was pre-washed with 5%wt/v sodium hydroxide solution prior to treatment with liquid epoxidized natural rubber (LENR). The concentration of LENR were varied from 5%-20%wt in toluene. The effects of LENR concentrations were studied in terms of mechanical properties and morphology formed. Melt-blending was performed using an internal mixer (Haake Rheomix 600). The processing parameters identified were 135°C temperature, 45 rpm rotor speed, 12 minutes processing time and at 20%wt MK fiber loading. The optimum LENR treatment concentration was obtained at 5%wt with tensile strength, tensile modulus, and impact strength of 10.3 MPa, 414.2 MPa and 14.4 kJ/m2 respectively. The tensile modulus of LENR-treated MK fiber filled NR/HDPE bio-composite has shown enhancement up to 16.7% higher than untreated MK fiber. The tensile and impact strength were decreased with increasing LENR concentration due to the broken of MK fibers to smaller particles and adhered to each other. FESEM micrographs confirmed the formation of fiber-fiber agglomeration in NR/HDPE blends. The optical microscope analysis shows MK fibers is shorter than original fiber lengths after NaOH-LENR surface modification. The internal bonding forces of MK fiber seems to be weaker than external force exerted on it, therefore, the MK fiber has broken to smaller particles and reduced the mechanical properties of NR/HDPE/MK(20%) bio-composite.

Declining Nutrient Concentrations in the Northeast Atlantic as a Result of a Weakening Subpolar Gyre

NASA Technical Reports Server (NTRS)

Johnson, Clare; Inall, Mark; Hakkinen, Sirpa

2013-01-01

Between 1996 and the mid-2000s the upper waters (200-700 m) of the Rockall Trough became warmer (+0.72 C), saltier (+0.088) and reduced in nitrate and phosphate (-2.00 Micron and -0.14 Micron respectively). These changes, out-with calculated errors, can be explained by the varying influence of southern versus subpolar water masses in the basin as the Subpolar Gyre weakened and contracted. Upper water properties strongly correlate with a measure of the strength of the Subpolar Gyre (the first principal component of sea surface height over the Subpolar North Atlantic) prior to the mid-2000s. As the gyre weakens, the upper layers of the trough become warmer (r -0.85), more saline (r -0.86) and reduced in nitrate and phosphate (r +0.81 and r +0.87 respectively). Further the proportion of subpolar waters in the basin decreases from around 50% to less than 20% (r +0. 88). Since the mid-2000s the Subpolar Gyre has been particularly weak. During this period temperatures decreased slightly (-0.21 1C), salinities remained near constant (35.410 +/- 0.005) and phosphate levels low and stable (0.68 +/- 0.02 Micron). These relative lack of changes are thought to be related to the maximum proportion of southern water masses within the Rockall Trough having been reached. Thus the upper water properties are no longer controlled by changes in the relative importance of different water masses in the basin (as prior to the mid-2000s), but rather a different process. We suggest that when the gyre is particularly weak the interannual changes in upper water properties in the Rockall Trough reflect changes in the source properties of the southern water masses. Since the early-2000s the Subpolar Gyre has been weaker than observed since 1992, or modelled since 1960-1970. Hence upper waters within the Rockall Trough may be warmer, saltier and more depleted in nitrate and phosphate than at any time in the last half century.

Study of oxide surfaces using time of flight positron annihilation induced Auger electron spectroscopy

NASA Astrophysics Data System (ADS)

Nadesalingam, Manori Prasadika

Transition metal oxides (TMOs) exhibit a rich collection of interesting and intriguing properties which can be used for wide variety of applications. In this dissertation, I will discuss the first PAES measurements on vacuum anneal induced changes in the surface layers of Cu2O/Ta, Cu 2O/TCO and oxidized Cu(100) prepared by spray coated, electrochemically deposition and thermal oxidation techniques respectively. PAES measurements on Cu2O/TCO shows that the a very large increase in the intensity of the Cu (M2,3 VV) Auger peak after annealing at 250°C. Similar but significantly smaller changes were observed in the EAES spectra consistent with the fact that PAES is primarily sensitive to the top-most atomic layer due to the fact that the positrons are trapped just outside the surface prior to annihilation while EAES samples several atomic layers. While PAES measurements on oxidized Cu(100) show a large monotonic increase in the intensity of the annihilation induced Cu (M2,3 VV) Auger peak as the sample is subjected to a series of isochronal anneals in vacuum up to annealing temperature 300°C. The intensity then decreases monotonically as the annealing temperature is increase to ˜500°C. These results provide a clear demonstration of the thermal reduction of the copper oxide surface after annealing at 300°C followed by re-oxidation of the copper surface at the higher annealing temperatures presumably due to the diffusion of subsurface oxygen to the surface.

Validation of a Laboratory Method for Evaluating Dynamic Properties of Reconstructed Equine Racetrack Surfaces

PubMed Central

Setterbo, Jacob J.; Chau, Anh; Fyhrie, Patricia B.; Hubbard, Mont; Upadhyaya, Shrini K.; Symons, Jennifer E.; Stover, Susan M.

2012-01-01

Background Racetrack surface is a risk factor for racehorse injuries and fatalities. Current research indicates that race surface mechanical properties may be influenced by material composition, moisture content, temperature, and maintenance. Race surface mechanical testing in a controlled laboratory setting would allow for objective evaluation of dynamic properties of surface and factors that affect surface behavior. Objective To develop a method for reconstruction of race surfaces in the laboratory and validate the method by comparison with racetrack measurements of dynamic surface properties. Methods Track-testing device (TTD) impact tests were conducted to simulate equine hoof impact on dirt and synthetic race surfaces; tests were performed both in situ (racetrack) and using laboratory reconstructions of harvested surface materials. Clegg Hammer in situ measurements were used to guide surface reconstruction in the laboratory. Dynamic surface properties were compared between in situ and laboratory settings. Relationships between racetrack TTD and Clegg Hammer measurements were analyzed using stepwise multiple linear regression. Results Most dynamic surface property setting differences (racetrack-laboratory) were small relative to surface material type differences (dirt-synthetic). Clegg Hammer measurements were more strongly correlated with TTD measurements on the synthetic surface than the dirt surface. On the dirt surface, Clegg Hammer decelerations were negatively correlated with TTD forces. Conclusions Laboratory reconstruction of racetrack surfaces guided by Clegg Hammer measurements yielded TTD impact measurements similar to in situ values. The negative correlation between TTD and Clegg Hammer measurements confirms the importance of instrument mass when drawing conclusions from testing results. Lighter impact devices may be less appropriate for assessing dynamic surface properties compared to testing equipment designed to simulate hoof impact (TTD). Potential Relevance Dynamic impact properties of race surfaces can be evaluated in a laboratory setting, allowing for further study of factors affecting surface behavior under controlled conditions. PMID:23227183

Sample selection, preparation methods, and the apparent tensile properties of silkworm (B. mori) cocoon silk.

PubMed

Reed, Emily J; Bianchini, Lindsay L; Viney, Christopher

2012-06-01

Reported literature values of the tensile properties of natural silk cover a wide range. While much of this inconsistency is the result of variability that is intrinsic to silk, some is also a consequence of differences in the way that silk is prepared for tensile tests. Here we explore how measured mechanical properties of Bombyx mori cocoon silk are affected by two intrinsic factors (the location from which the silk is collected within the cocoon, and the color of the silk), and two extrinsic factors (the storage conditions prior to testing, and different styles of reeling the fiber). We find that extrinsic and therefore controllable factors can affect the properties more than the intrinsic ones studied. Our results suggest that enhanced inter-laboratory collaborations, that lead to standardized sample collection, handling, and storage protocols prior to mechanical testing, would help to decrease unnecessary (and complicating) variation in reported tensile properties. Copyright © 2011 Wiley Periodicals, Inc.

Predicting Properties of Unidirectional-Nanofiber Composites

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Handler, Louis M.; Manderscheid, Jane

2008-01-01

A theory for predicting mechanical, thermal, electrical, and other properties of unidirectional-nanofiber/matrix composite materials is based on the prior theory of micromechanics of composite materials. In the development of the present theory, the prior theory of micromechanics was extended, through progressive substructuring, to the level of detail of a nanoscale slice of a nanofiber. All the governing equations were then formulated at this level. The substructuring and the equations have been programmed in the ICAN/JAVA computer code, which was reported in "ICAN/JAVA: Integrated Composite Analyzer Recoded in Java" (LEW-17247), NASA Tech Briefs, Vol. 26, No. 12 (December 2002), page 36. In a demonstration, the theory as embodied in the computer code was applied to a graphite-nanofiber/epoxy laminate and used to predict 25 properties. Most of the properties were found to be distributed along the through-the-thickness direction. Matrix-dependent properties were found to have bimodal through-the-thickness distributions with discontinuous changes from mode to mode.

Engineered Multifunctional Surfaces for Fluid Handling

NASA Technical Reports Server (NTRS)

Thomas, Chris; Ma, Yonghui; Weislogel, Mark

2012-01-01

Designs incorporating variations in capillary geometry and hydrophilic and/or antibacterial surface properties have been developed that are capable of passive gas/liquid separation and passive water flow. These designs can incorporate capillary grooves and/or surfaces arranged to create linear and circumferential capillary geometry at the micro and macro scale, radial fin configurations, micro holes and patterns, and combinations of the above. The antibacterial property of this design inhibits the growth of bacteria or the development of biofilm. The hydrophilic property reduces the water contact angle with a treated substrate such that water spreads into a thin layer atop the treated surface. These antibacterial and hydrophilic properties applied to a thermally conductive surface, combined with capillary geometry, create a novel heat exchanger capable of condensing water from a humid, two-phase water and gas flow onto the treated heat exchanger surfaces, and passively separating the condensed water from the gas flow in a reduced gravity application. The overall process to generate the antibacterial and hydrophilic properties includes multiple steps to generate the two different surface properties, and can be divided into two major steps. Step 1 uses a magnetron-based sputtering technique to implant the silver atoms into the base material. A layer of silver is built up on top of the base material. Completion of this step provides the antibacterial property. Step 2 uses a cold-plasma technique to generate the hydrophilic surface property on top of the silver layer generated in Step 1. Completion of this step provides the hydrophilic property in addition to the antibacterial property. Thermally conductive materials are fabricated and then treated to create the antibacterial and hydrophilic surface properties. The individual parts are assembled to create a condensing heat exchanger with antibacterial and hydrophilic surface properties and capillary geometry, which is capable of passive phase separation in a reduced gravity application. The plasma processes for creating antibacterial and hydrophilic surface properties are suitable for applications where water is present on an exposed surface for an extended time, such that bacteria or biofilms could form, and where there is a need to manage the water on the surface. The processes are also suitable for applications where only the hydrophilic property is needed. In particular, the processes are applicable to condensing heat exchangers (CHXs), which benefit from the antibacterial properties as well as the hydrophilic properties. Water condensing onto the control surfaces of the CHX will provide the moist conditions necessary for the growth of bacteria and the formation of biofilms. The antibacterial properties of the base layer (silver) will mitigate and prevent the growth of bacteria and formation of biofilms that would otherwise reduce the CHX performance. In addition, the hydrophilic properties reduce the water contact angle and prevent water droplets from bridging between control surfaces. Overall, the hydrophilic properties reduce the pressure drop across the CHX.

Functional properties and in vitro trypsin digestibility of red kidney bean (Phaseolus vulgaris L.) protein isolate: Effect of high-pressure treatment.

PubMed

Yin, Shou-Wei; Tang, Chuan-He; Wen, Qi-Biao; Yang, Xiao-Quan; Li, Lin

2008-10-15

The effects of high-pressure (HP) treatment at 200-600MPa, prior to freeze-drying, on some functional properties and in vitro trypsin digestibility of vicilin-rich red kidney bean (Phaseolus vulgaris L.) protein isolate (KPI) were investigated. Surface hydrophobicity and free sulfhydryl (SH) and disulfide bond (SS) contents were also evaluated. HP treatment resulted in gradual unfolding of protein structure, as evidenced by gradual increases in fluorescence strength and SS formation from SH groups, and decrease in denaturation enthalpy change. The protein solubility of KPI was significantly improved at pressures of 400MPa or higher, possibly due to formation of soluble aggregate from insoluble precipitate. HP treatment at 200 and 400MPa significantly increased emulsifying activity index (EAI) and emulsion stability index (ESI); however, EAI was significantly decreased at 600MPa (relative to untreated KPI). The thermal stability of the vicilin component was not affected by HP treatment. Additionally, in vitro trypsin digestibility of KPI was decreased only at a pressure above 200MPa and for long incubation time (e.g., 120min). The data suggest that some physiochemical and functional properties of vicilin-rich kidney proteins can be improved by means of high-pressure treatment. Copyright © 2008 Elsevier Ltd. All rights reserved.

Zero-valent iron/iron oxide-oxyhydroxide/graphene as a magnetic sorbent for the enrichment of polychlorinated biphenyls, polyaromatic hydrocarbons and phthalates prior to gas chromatography-mass spectrometry.

PubMed

Karamani, Anna A; Douvalis, Alexios P; Stalikas, Constantine D

2013-01-04

A composite magnetic material consisting of zero-valent iron, iron oxide-oxyhydroxide and graphene was synthesized and used successfully as a sorbent for the micro solid-phase extraction of PAHs, PCBs and phthalic acid esters. The components endow the composite with multiple characteristics such as adsorption capability and facile removal due to its magnetic properties. Due to the π-π electrostatic stacking property of graphene, the high specific surface area and the adsorption capability of both components, the resulting black flaky Fe(0)/iron oxide-oxyhydroxide/graphene composite showed high extraction efficiency for the target analytes from water samples. Compared with the neat graphene, the composite material has improved properties in terms of microextraction capabilities as both the hydrophobic graphene and zero-valent iron participate in the adsorption of the hydrophobic molecules. The precision from the extraction of all three groups of compounds was lower than 7% and the recoveries were from 90 to 93% from a spiked lake water sample. The high recoveries in relation to the low final volume of the desorption solvent ensure high preconcentration efficiency and a promising sorbent for analytical applications. Copyright © 2012 Elsevier B.V. All rights reserved.

Correlations between the Dielectric Properties and Exterior Morphology of Cells Revealed by Dielectrophoretic Field-Flow Fractionation

PubMed Central

Gascoyne, Peter R. C.; Shim, Sangjo; Noshari, Jamileh; Becker, Frederick F.; Stemke-Hale, Katherine

2013-01-01

Although dielectrophoresis (DEP) has great potential for addressing clinical cell isolation problems based on cell dielectric differences, a biological basis for predicting the DEP behavior of cells has been lacking. Here, the dielectric properties of the NCI-60 panel of tumor cell types have been measured by dielectrophoretic (DEP) field-flow fractionation, correlated with the exterior morphologies of the cells during growth, and compared with the dielectric and morphological characteristics of the subpopulations of peripheral blood. In agreement with earlier findings, cell total capacitance varied with both cell size and plasma membrane folding and the dielectric properties of the NCI-60 cell types in suspension reflected the plasma membrane area and volume of the cells at their growth sites. Therefore, the behavior of cells in DEP-based manipulations is largely determined by their exterior morphological characteristics prior to release into suspension. As a consequence, DEP is able to discriminate between cells of similar size having different morphological origins, offering a significant advantage over size-based filtering for isolating circulating tumor cells, for example. The findings provide a framework for anticipating cell dielectric behavior on the basis of structure-function relationships and suggest that DEP should be widely applicable as a surface marker-independent method for sorting cells. PMID:23172680

Hydrophobic and optical characteristics of graphene and graphene oxide films transferred onto functionalized silica particles deposited glass surface

NASA Astrophysics Data System (ADS)

Yilbas, B. S.; Ibrahim, A.; Ali, H.; Khaled, M.; Laoui, T.

2018-06-01

Hydrophobic and optical transmittance characteristics of the functionalized silica particles on the glass surface prior and after transfer of graphene and graphene oxide films on the surface are examined. Nano-size silica particles are synthesized and functionalized via chemical grafting and deposited onto a glass surface. Graphene film, grown on copper substrate, was transferred onto the functionalized silica particles surface through direct fishing method. Graphene oxide layer was deposited onto the functionalized silica particles surface via spin coating technique. Morphological, hydrophobic, and optical characteristics of the functionalized silica particles deposited surface prior and after graphene and graphene oxide films transfer are examined using the analytical tools. It is found that the functionalized silica particles are agglomerated at the surface forming packed structures with few micro/nano size pores. This arrangement gives rise to water droplet contact angle and contact angle hysteresis in the order of 163° and 2°, respectively, and remains almost uniform over the entire surface. Transferring graphene and depositing graphene oxide films over the functionalized silica particles surface lowers the water droplet contact angle slightly (157-160°) and increases the contact angle hysteresis (4°). The addition of the graphene and graphene oxide films onto the surface of the deposited functionalized silica particles improves the optical transmittance.

UCAV path planning in the presence of radar-guided surface-to-air missile threats

NASA Astrophysics Data System (ADS)

Zeitz, Frederick H., III

This dissertation addresses the problem of path planning for unmanned combat aerial vehicles (UCAVs) in the presence of radar-guided surface-to-air missiles (SAMs). The radars, collocated with SAM launch sites, operate within the structure of an Integrated Air Defense System (IADS) that permits communication and cooperation between individual radars. The problem is formulated in the framework of the interaction between three sub-systems: the aircraft, the IADS, and the missile. The main features of this integrated model are: The aircraft radar cross section (RCS) depends explicitly on both the aspect and bank angles; hence, the RCS and aircraft dynamics are coupled. The probabilistic nature of IADS tracking is accounted for; namely, the probability that the aircraft has been continuously tracked by the IADS depends on the aircraft RCS and range from the perspective of each radar within the IADS. Finally, the requirement to maintain tracking prior to missile launch and during missile flyout are also modeled. Based on this model, the problem of UCAV path planning is formulated as a minimax optimal control problem, with the aircraft bank angle serving as control. Necessary conditions of optimality for this minimax problem are derived. Based on these necessary conditions, properties of the optimal paths are derived. These properties are used to discretize the dynamic optimization problem into a finite-dimensional, nonlinear programming problem that can be solved numerically. Properties of the optimal paths are also used to initialize the numerical procedure. A homotopy method is proposed to solve the finite-dimensional, nonlinear programming problem, and a heuristic method is proposed to improve the discretization during the homotopy process. Based upon the properties of numerical solutions, a method is proposed for parameterizing and storing information for later recall in flight to permit rapid replanning in response to changing threats. Illustrative examples are presented that confirm the standard flying tactics of "denying range, aspect, and aim," by yielding flight paths that "weave" to avoid long exposures of aspects with large RCS.

GROUND WATER CONTAMINATION POTENTIAL FROM STORMWATER INFILTRATION

EPA Science Inventory

Prior to urbanization, ground water recharge resulted from infiltration of precipitation through pervious surfaces, including grasslands and woods. This infiltration water was relatively uncontaminated. With urbanization, the permeable soil surface area through which recharge by...

26 CFR 301.6336-1 - Sale of perishable goods.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 26 Internal Revenue 18 2010-04-01 2010-04-01 false Sale of perishable goods. 301.6336-1 Section...-1 Sale of perishable goods. (a) Appraisal of certain seized property. If the district director... property, which notice shall be confirmed in writing prior to sale. The property shall be returned to the...

Capitalization of Charter Schools into Residential Property Values

ERIC Educational Resources Information Center

Brehm, Margaret; Imberman, Scott A.; Naretta, Michael

2017-01-01

Although prior research has found clear impacts of schools and school quality on property values, little is known about whether charter schools have similar effects. Using sale price data for residential properties in Los Angeles County from 2008 to 2011 we estimate the neighborhood level impact of charter schools on housing prices. Using an…

44 CFR 11.78 - Computation of amount of award.

Code of Federal Regulations, 2011 CFR

2011-10-01

... in the value of the property. Subject to these limitations, the amount allowable is either: (1) The depreciated value, immediately prior to the loss or damage, of property lost or damaged beyond economical... the item (either the price paid in cash or property, or the value at the time of acquisition if not...

Elevated temperature mechanical properties and residual tensile properties of two cast superalloys and several nickel-base oxide dispersion strengthened alloys

NASA Technical Reports Server (NTRS)

Whittenberger, J. D.

1981-01-01

The elevated temperature tensile, stress-rupture and creep properties and residual tensile properties after creep straining have been determined for two cast superalloys and several wrought Ni-16Cr-4Al-yttria oxide dispersion strengthened (ODS) alloys. The creep behavior of the ODS alloys is similar to that of previously studied ODS nickel alloys. In general, the longitudinal direction is stronger than the long transverse direction, and creep is at least partially due to a diffusional creep mechanism as dispersoid-free zones were observed after creep-rupture testing. The tensile properties of the nickel-base superalloy B-1900 and cobalt-base superalloy MAR-M509 are not degraded by prior elevated temperature creep straining (at least up to 1 pct) between 1144 and 1366 K. On the other hand, the room temperature tensile properties of ODS nickel-base alloys can be reduced by prior creep strains of 0.5 pct or less between 1144 and 1477 K, with the long transverse direction being more susceptible to degradation than the longitudinal direction.

Synthesis and controlled self-assembly of UV-responsive gold nanoparticles in block copolymer templates.

PubMed

Song, Dong-Po; Wang, Xinyu; Lin, Ying; Watkins, James J

2014-11-06

We demonstrate the facile synthesis of gold nanoparticles (GNPs) functionalized by UV-responsive block copolymer ligands, poly(styrene)-b-poly(o-nitrobenzene acrylate)-SH (PS-b-PNBA-SH), followed by their targeted distribution within a lamellae-forming poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer. The multilayer, micelle-like structure of the GNPs consists of a gold core, an inner PNBA layer, and an outer PS layer. The UV-sensitive PNBA segment can be deprotected into a layer containing poly(acrylic acid) (PAA) when exposed to UV light at 365 nm, which enables the simple and precise tuning of GNP surface properties from hydrophobic to amphiphilic. The GNPs bearing ligands of different chemical compositions were successfully and selectively incorporated into the PS-b-P2VP block copolymer, and UV light showed a profound influence on the spatial distributions of GNPs. Prior to UV exposure, GNPs partition along the interfaces of PS and P2VP domains, while the UV-treated GNPs are incorporated into P2VP domains as a result of hydrogen bond interactions between PAA on the gold surface and P2VP domains. This provides an easy way of controlling the arrangement of nanoparticles in polymer matrices by tailoring the nanoparticle surface using UV light.

Successful Surface Treatments for Reducing Instabilities in Advanced Nickel-base Superalloys for Turbine Blades

NASA Technical Reports Server (NTRS)

Locci, Ivan E.; MacKay, Rebecca A.; Garg, Anita; Ritzert, Frank J.

2004-01-01

An optimized carburization treatment has been developed to mitigate instabilities that form in the microstructures of advanced turbine airfoil materials. Current turbine airfoils consist of a single crystal superalloy base that provides the mechanical performance of the airfoil, a thermal barrier coating (TBC) that reduces the temperature of the base superalloy, and a bondcoat between the superalloy and the TBC, that improves the oxidation and corrosion resistance of the base superalloy and the spallation resistance of the TBC. Advanced nickel-base superalloys containing high levels of refractory metals have been observed to develop an instability called secondary reaction zone (SRZ), which can form beneath diffusion aluminide bondcoats. This instability between the superalloy and the bondcoat has the potential of reducing the mechanical properties of thin-wall turbine airfoils. Controlled gas carburization treatments combined with a prior stress relief heat treatment and adequate surface preparation have been utilized effectively to minimize the formation of SRZ. These additional processing steps are employed before the aluminide bondcoat is deposited and are believed to change the local chemistry and local stresses of the surface of the superalloy. This paper presents the detailed processing steps used to reduce SRZ between platinum aluminide bondcoats and advanced single crystal superalloys.

Removal of model viruses, E. coli and Cryptosporidium oocysts from surface water by zirconium and chitosan coagulants.

PubMed

Christensen, Ekaterina; Nilsen, Vegard; Håkonsen, Tor; Heistad, Arve; Gantzer, Christophe; Robertson, Lucy J; Myrmel, Mette

2017-10-01

The present work evaluates the effect of contact filtration, preceded by coagulation with zirconium (Zr) and chitosan coagulants, on model microorganisms and waterborne pathogens. River water intended for potable water production was spiked with MS2 and Salmonella Typhimurium 28B bacteriophages, Escherichia coli, and Cryptosporidium parvum oocysts prior to coagulation. The hygienic performance demonstrated by Zr comprised 3.0-4.0 log 10 removal of viruses and 5.0-6.0 log 10 removal of E. coli and C. parvum oocysts. Treatment with chitosan resulted in a removal of 2.5-3.0 log 10 of viruses and parasites, and 4.5-5.0 log 10 of bacteria. A reference coagulant, polyaluminium chloride (PACl), gave a 2.5-3.0 log 10 removal of viruses and 4.5 log 10 of E. coli. These results indicate that both Zr and chitosan enable adequate removal of microorganisms from surface water. The present study also attempts to assess removal rates of the selected microorganisms with regard to their size and surface properties. The isoelectric point of the Salmonella Typhimurium 28B bacteriophage is reported for the first time. The retention of the selected microorganisms in the filter bed appeared to have some correlation with their size, but the effect of the charge remained unclear.

Burst Ductility of Zirconium Clads: The Defining Role of Residual Stress

NASA Astrophysics Data System (ADS)

Kumar, Gulshan; Kanjarla, A. K.; Lodh, Arijit; Singh, Jaiveer; Singh, Ramesh; Srivastava, D.; Dey, G. K.; Saibaba, N.; Doherty, R. D.; Samajdar, Indradev

2016-08-01

Closed end burst tests, using room temperature water as pressurizing medium, were performed on a number of industrially produced zirconium (Zr) clads. A total of 31 samples were selected based on observed differences in burst ductility. The latter was represented as total circumferential elongation or TCE. The selected samples, with a range of TCE values (5 to 35 pct), did not show any correlation with mechanical properties along axial direction, microstructural parameters, crystallographic textures, and outer tube-surface normal ( σ 11) and shear ( τ 13) components of the residual stress matrix. TCEs, however, had a clear correlation with hydrostatic residual stress ( P h), as estimated from tri-axial stress analysis on the outer tube surface. Estimated P h also scaled with measured normal stress ( σ 33) at the tube cross section. An elastic-plastic finite element model with ductile damage failure criterion was developed to understand the burst mechanism of zirconium clads. Experimentally measured P h gradients were imposed on a solid element continuum finite element (FE) simulation to mimic the residual stresses present prior to pressurization. Trends in experimental TCEs were also brought out with computationally efficient shell element-based FE simulations imposing the outer tube-surface P h values. Suitable components of the residual stress matrix thus determined the burst performance of the Zr clads.

WISDOM, a polarimetric GPR for the shallow subsurface characterization

NASA Astrophysics Data System (ADS)

Ciarletti, V.; Plettemeier, D.; Hassen-Kodja, R.; Clifford, S. M.; Wisdom Team

2011-12-01

WISDOM (Water Ice and Subsurface Deposit Observations on Mars) is a polarimetric Ground Penetrating Radar (GPR) that has been selected to be part of the Pasteur payload onboard the Rover of the 2018 ExoMars mission. It will perform large-scale scientific investigations of the sub-surface of the landing site and provide precise information about the subsurface structure prior to drilling. WISDOM has been designed to provide accurate information on the sub-surface structure down to a depth in excess to 2 meters (commensurate to the drill capacities) with a vertical resolution of a several centimetres. It will give access to the geological structure, electromagnetic nature, and, possibly, to the hydrological state of the shallow subsurface by retrieving the layering and properties of the layers and buried reflectors. The data will also be used to determine the most promising locations to collect underground samples with the drilling system mounted on board the rover. Polarimetric measurements have been recently acquired on perfectly known targets as well as in natural environments. They demonstrated the ability to provide a better understanding of sub-surface structure and significantly reduce the ambiguity associated with identifying the location of off-nadir reflectors, relative to the rover path. This work describes the instrument and its operating modes with particular emphasis on its polarimetric capacities.

Influence of Atomic Hydrogen, Band Bending, and Defects in the Top Few Nanometers of Hydrothermally Prepared Zinc Oxide Nanorods

NASA Astrophysics Data System (ADS)

Al-Saadi, Mubarak J.; Al-Harthi, Salim H.; Kyaw, Htet H.; Myint, Myo T. Z.; Bora, Tanujjal; Laxman, Karthik; Al-Hinai, Ashraf; Dutta, Joydeep

2017-01-01

We report on the surface, sub-surface (top few nanometers) and bulk properties of hydrothermally grown zinc oxide (ZnO) nanorods (NRs) prior to and after hydrogen treatment. Upon treating with atomic hydrogen (H*), upward and downward band bending is observed depending on the availability of molecular H2O within the structure of the NRs. In the absence of H2O, the H* treatment demonstrated a cleaning effect of the nanorods, leading to a 0.51 eV upward band bending. In addition, enhancement in the intensity of room temperature photoluminescence (PL) signals due to the creation of new surface defects could be observed. The defects enhanced the visible light activity of the ZnO NRs which were subsequently used to photocatalytically degrade aqueous phenol under simulated sunlight. On the contrary, in the presence of H2O, H* treatment created an electronic accumulation layer inducing downward band bending of 0.45 eV ( 1/7th of the bulk ZnO band gap) along with the weakening of the defect signals as observed from room temperature photoluminescence spectra. The results suggest a plausible way of tailoring the band bending and defects of the ZnO NRs through control of H2O/H* species.

Synthesis of highly monodisperse particles composed of a magnetic core and fluorescent shell.

PubMed

Nagao, Daisuke; Yokoyama, Mikio; Yamauchi, Noriko; Matsumoto, Hideki; Kobayashi, Yoshio; Konno, Mikio

2008-09-02

Highly monodisperse particles composed of a magnetic silica core and fluorescent polymer shell were synthesized with a combined technique of heterocoagulation and soap-free emulsion polymerization. Prior to heterocoagulation, monodisperse, submicrometer-sized silica particles were prepared with the Stober method, and magnetic nanoparticles were prepared with a modified Massart method in which a cationic silane coupling agent of N-trimethoxysilylpropyl- N, N, N-trimethylammonium chloride was added just after coprecipitation of Fe (2+) and Fe (3+). The silica particles with negative surface potential were heterocoagulated with the magnetic nanoparticles with positive surface potential. The magnetic silica particles obtained with the heterocoagulation were treated with sodium silicate to modify their surfaces with silica. In the formation of a fluorescent polymer shell onto the silica-coated magnetic silica cores, an amphoteric initiator of 2,2'-azobis[ N-(2-carboxyethyl)-2-2-methylpropionamidine] (VA-057) was used to control the colloidal stability of the magnetic cores during the polymer coating. The polymerization of St in the presence of a hydrophobic fluorophore of pyrene could coat the cores with fluorescent polymer shells, resulting in monodisperse particles with a magnetic silica core and fluorescent polymer shell. Measurements of zeta potential for the composite particles in different pH values indicated that the composite particles had an amphoteric property originating from VA-057 initiator.

Antecedent moisture content and soil texture effects on infiltration and erosion

NASA Astrophysics Data System (ADS)

Mamedov, A. I.; Huang, C.; Levy, G. J.

2006-12-01

Water infiltration, seal formation, runoff and erosion depend on the soil's inherent properties and surface conditions. Most erosion models consider only soil inherent properties (mainly texture) in assessing infiltration and erosion without consideration of spatial and temporary variation in the surface condition, particularly the antecedent moisture content. We studied the interaction of two different surface conditions, i.e. antecedent moisture content (AMC) and aging (timing after wetting) on infiltration (IR), seal formation (runoff generation) and erosion in four soils varying from loam to clay. Soil samples were packed in erosion box and wetted with different amounts of water (0, 1, 2, 3, 4, 6, 8, or 16 mm) to obtain a wide moisture range (i.e., pF 0-6.2, or from air dry to full saturation). The boxes were put in plastic bags and allowed to age for 0.01, 1, 3, or 7 days. Then the soil in the erosion box exposed to 60 mm of rain. At no aging final IR of soils did not change significantly, but runoff volume (a measure for seal development) and soil loss increased with an increase in AMC mainly because of aggregate breakdown. For any given aging, the highest IR and smallest runoff volume and soil loss were obtained at the intermediate AMC levels (pF 2.4-4.2, between wilting point and field capacity). For instance, in the clay soil to which 3 mm of water (pF~2.7) was added, as aging increased from one to seven days, final IR increased from 5.3 to 7.9 mm h-1, while runoff and soil loss decreased from 34 mm to 22 mm, and from 630 to 360 g m2 respectively. At this AMC range, increasing aging time resulted in up to 40% increase in IR and decrease in runoff or soil loss. This tendency significantly more pronounced for clay soils because water-filled pores in the clay fabric were considered active in the stabilization process and the development of cohesive bonds between and within particles during the aging period. The results of this study are important for soil erosion modeling. In order to improve the prediction capabilities of erosion models, temporal and spatial variation of soil moisture content (AMC, wetting and aging) prior to erosive rainstorms should be considered and or incorporated. In addition, management practices could be adapted to diminish the severe soil moisture variation, where ever possible, (minimum till or no-till with known residue) to maintain the soil surface at a desired AMC level prior to expected rainstorms in order to decrease soil susceptibility to seal formation, runoff and soil loss.

A Facile in Situ and UV Printing Process for Bioinspired Self-Cleaning Surfaces

PubMed Central

González Lazo, Marina A.; Katrantzis, Ioannis; Dalle Vacche, Sara; Karasu, Feyza; Leterrier, Yves

2016-01-01

A facile in situ and UV printing process was demonstrated to create self-cleaning synthetic replica of natural petals and leaves. The process relied on the spontaneous migration of a fluorinated acrylate surfactant (PFUA) within a low-shrinkage acrylated hyperbranched polymer (HBP) and its chemical immobilization at the polymer-air interface. Dilute concentrations of 1 wt. % PFUA saturated the polymer-air interface within 30 min, leading to a ten-fold increase of fluorine concentration at the surface compared with the initial bulk concentration and a water contact angle (WCA) of 108°. A 200 ms flash of UV light was used to chemically crosslink the PFUA at the HBP surface prior to UV printing with a polydimethylsiloxane (PDMS) negative template of red and yellow rose petals and lotus leaves. This flash immobilization hindered the reverse migration of PFUA within the bulk HBP upon contacting the PDMS template, and enabled to produce texturized surfaces with WCA well above 108°. The synthetic red rose petal was hydrophobic (WCA of 125°) and exhibited the adhesive petal effect. It was not superhydrophobic due to insufficient concentration of fluorine at its surface, a result of the very large increase of the surface of the printed texture. The synthetic yellow rose petal was quasi-superhydrophobic (WCA of 143°, roll-off angle of 10°) and its self-cleaning ability was not good also due to lack of fluorine. The synthetic lotus leaf did not accurately replicate the intricate nanotubular crystal structures of the plant. In spite of this, the fluorine concentration at the surface was high enough and the leaf was superhydrophobic (WCA of 151°, roll-off angle below 5°) and also featured self-cleaning properties. PMID:28773860

X-ray photoelectron spectroscopy (XPS) investigation of the surface film on magnesium powders.

PubMed

Burke, Paul J; Bayindir, Zeynel; Kipouros, Georges J

2012-05-01

Magnesium (Mg) and its alloys are attractive for use in automotive and aerospace applications because of their low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. Powder metallurgy may be a suitable solution for forming near-net-shape parts. However, sintering pure magnesium presents difficulties due to surface film that forms on the magnesium powder particles. The present work investigates the composition of the surface film that forms on the surface of pure magnesium powders exposed to atmospheric conditions and on pure magnesium powders after compaction under uniaxial pressing at a pressure of 500 MPa and sintering under argon at 600 °C for 40 minutes. Initially, focused ion beam microscopy was utilized to determine the thickness of the surface layer of the magnesium powder and found it to be ~10 nm. The X-ray photoelectron analysis of the green magnesium sample prior to sintering confirmed the presence of MgO, MgCO(3)·3H(2)O, and Mg(OH)(2) in the surface layer of the powder with a core of pure magnesium. The outer portion of the surface layer was found to contain MgCO(3)·3H(2)O and Mg(OH)(2), while the inner portion of the layer is primarily MgO. After sintering, the MgCO(3)·3H(2)O was found to be almost completely absent, and the amount of Mg(OH)(2) was also decreased significantly. This is postulated to occur by decomposition of the compounds to MgO and gases during the high temperature of sintering. An increase in the MgO content after sintering supports this theory.

Grinding and its influence to ground surface durability

NASA Astrophysics Data System (ADS)

Holesovsky, F.; Novak, M.

2011-01-01

A number of parameters of running process effect on the formed surface at grinding. Above all, the following influences can be mentioned: grinding wheel speed, workpiece speed, tool properties, rigidity of machine tool, etc. The plastic deformation and thermal load of surface layer are evoked at the action of cutting conditions. A new surface keeps the definite properties, which are given by its roughness, surface profile, geometry accuracy, intensity and residual stress distribution, respectively microhardness course in surface layer and changes of microstructure in this layer. The surface properties predict the surface behaviour in the real machinery at the dynamical, respectively static loading. At the load, the changes of surface properties proceed, e.g. roughness, residual stress. Simultaneously, changes of surface properties influence the durability of machine part and can also lead to surface damage and machine part breakdown. The slackness can also evoke the cracks, which leads to the fracture. The behaviour of part differs in the operating environment without and with oil or in the corrosion environment.

Electro-Optic Properties of Holographically Patterned, Polymer Stabilized Cholesteric Liquid Crystals (Preprint)

DTIC Science & Technology

2007-01-01

Electro - optic properties of cholesteric liquid crystals with holographically patterned polymer stabilization were examined. It is hypothesized that...enhanced electro - optic properties of the final device. Prior to holographic patterning, polymer stabilization with large elastic memory was generated by way... electro - optic properties appear to stem from a single dimension domain size increase, which allows for a reduction in the LC/polymer interaction.

Acoustical Properties of Mud Sediments

DTIC Science & Technology

2015-09-30

Acoustical Properties of Mud Sediments Allan D. Pierce Boston University 399 Quaker Meeting House Road P. O. Box 339 East Sandwich, MA 03537...shallow-ocean mud sediments. Other goals are to assess prior data relating to the acoustic properties of mud and to provide guidance in the...development and interpretation of experiments. A related goal is to construct models that will guide inversion techniques for inferring properties of mud

Hyperproperties

DTIC Science & Technology

2016-01-14

hyperproperty and a liveness hyperproperty. A verification technique for safety hyperproperties is given and is shown to generalize prior tech- niques for...liveness properties are affiliated with specific verification methods. An analogous theory for security policies would be appealing. The fact that security...verified by using invariance arguments. Our verification methodology generalizes prior work on using invariance arguments to verify information-flow

40 CFR 312.20 - All appropriate inquiries.

Code of Federal Regulations, 2011 CFR

2011-07-01

... inquiries” pursuant to CERCLA section 101(35)(B) must be conducted within one year prior to the date of... one year prior to the date of acquisition of the subject property; (3) Notwithstanding paragraph (b)(2... this subpart. (g) To the extent there are data gaps (as defined in § 312.10) in the information...

Validated measurements of microbial loads on environmental surfaces in intensive care units before and after disinfecting cleaning.

PubMed

Frickmann, H; Bachert, S; Warnke, P; Podbielski, A

2018-03-01

Preanalytic aspects can make results of hygiene studies difficult to compare. Efficacy of surface disinfection was assessed with an evaluated swabbing procedure. A validated microbial screening of surfaces was performed in the patients' environment and from hands of healthcare workers on two intensive care units (ICUs) prior to and after a standardized disinfection procedure. From a pure culture, the recovery rate of the swabs for Staphylococcus aureus was 35%-64% and dropped to 0%-22% from a mixed culture with 10-times more Staphylococcus epidermidis than S. aureus. Microbial surface loads 30 min before and after the cleaning procedures were indistinguishable. The quality-ensured screening procedure proved that adequate hygiene procedures are associated with a low overall colonization of surfaces and skin of healthcare workers. Unchanged microbial loads before and after surface disinfection demonstrated the low additional impact of this procedure in the endemic situation when the pathogen load prior to surface disinfection is already low. Based on a validated screening system ensuring the interpretability and reliability of the results, the study confirms the efficiency of combined hand and surface hygiene procedures to guarantee low rates of bacterial colonization. © 2017 The Society for Applied Microbiology.

Can Reduced-Step Polishers Be as Effective as Multiple-Step Polishers in Enhancing Surface Smoothness?

PubMed

Kemaloglu, Hande; Karacolak, Gamze; Turkun, L Sebnem

2017-02-01

The aim of this study was to evaluate the effects of various finishing and polishing systems on the final surface roughness of a resin composite. Hypotheses tested were: (1) reduced-step polishing systems are as effective as multiple-step systems on reducing the surface roughness of a resin composite and (2) the number of application steps in an F/P system has no effect on reducing surface roughness. Ninety discs of a nano-hybrid resin composite were fabricated and divided into nine groups (n = 10). Except the control, all of the specimens were roughened prior to be polished by: Enamel Plus Shiny, Venus Supra, One-gloss, Sof-Lex Wheels, Super-Snap, Enhance/PoGo, Clearfil Twist Dia, and rubber cups. The surface roughness was measured and the surfaces were examined under scanning electron microscope. Results were analyzed with analysis of variance and Holm-Sidak's multiple comparisons test (p < 0.05). Significant differences were found among the surface roughness of all groups (p < 0.05). The smoothest surfaces were obtained under Mylar strips and the results were not different than Super-Snap, Enhance/PoGo, and Sof-Lex Spiral Wheels. The group that showed the roughest surface was the rubber cup group and these results were similar to those of the One-gloss, Enamel Plus Shiny, and Venus Supra groups. (1) The number of application steps has no effect on the performance of F/P systems. (2) Reduced-step polishers used after a finisher can be preferable to multiple-step systems when used on nanohybrid resin composites. (3) The effect of F/P systems on surface roughness seems to be material-dependent rather than instrument- or system-dependent. Reduced-step systems used after a prepolisher can be an acceptable alternative to multiple-step systems on enhancing the surface smoothness of a nanohybrid composite; however, their effectiveness depends on the materials' properties. (J Esthet Restor Dent 29:31-40, 2017). © 2016 Wiley Periodicals, Inc.

Surface Analysis Cluster Tool | Materials Science | NREL

Science.gov Websites

spectroscopic ellipsometry during film deposition. The cluster tool can be used to study the effect of various prior to analysis. Here we illustrate the surface cleaning effect of an aqueous ammonia treatment on a

Methods To Characterize Contaminant Residuals After Environmental Dredging

EPA Science Inventory

Environmental dredging is a common remedial action for managing contaminated sediments. However, post dredging contaminant concentrations in surface sediment are difficult to predict prior to initiating dredging actions. In some cases, post surface concentrations have been high...

Impact of recess etching and surface treatments on ohmic contacts regrown by molecular-beam epitaxy for AlGaN/GaN high electron mobility transistors

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

Joglekar, S.; Azize, M.; Palacios, T.

Ohmic contacts fabricated by regrowth of n{sup +} GaN are favorable alternatives to metal-stack-based alloyed contacts in GaN-based high electron mobility transistors. In this paper, the influence of reactive ion dry etching prior to regrowth on the contact resistance in AlGaN/GaN devices is discussed. We demonstrate that the dry etch conditions modify the surface band bending, dangling bond density, and the sidewall depletion width, which influences the contact resistance of regrown contacts. The impact of chemical surface treatments performed prior to regrowth is also investigated. The sensitivity of the contact resistance to the surface treatments is found to depend uponmore » the dangling bond density of the sidewall facets exposed after dry etching. A theoretical model has been developed in order to explain the observed trends.« less

Evaluation of multi-scale mineralized collagen-polycaprolactone composites for bone tissue engineering.

PubMed

Weisgerber, D W; Erning, K; Flanagan, C L; Hollister, S J; Harley, B A C

2016-08-01

A particular challenge in biomaterial development for treating orthopedic injuries stems from the need to balance bioactive design criteria with the mechanical and geometric constraints governed by the physiological wound environment. Such trade-offs are of particular importance in large craniofacial bone defects which arise from both acute trauma and chronic conditions. Ongoing efforts in our laboratory have demonstrated a mineralized collagen biomaterial that can promote human mesenchymal stem cell osteogenesis in the absence of osteogenic media but that possesses suboptimal mechanical properties in regards to use in loaded wound sites. Here we demonstrate a multi-scale composite consisting of a highly bioactive mineralized collagen-glycosaminoglycan scaffold with micron-scale porosity and a polycaprolactone support frame (PCL) with millimeter-scale porosity. Fabrication of the composite was performed by impregnating the PCL support frame with the mineral scaffold precursor suspension prior to lyophilization. Here we evaluate the mechanical properties, permeability, and bioactivity of the resulting composite. Results indicated that the PCL support frame dominates the bulk mechanical response of the composite resulting in a 6000-fold increase in modulus compared to the mineral scaffold alone. Similarly, the incorporation of the mineral scaffold matrix into the composite resulted in a higher specific surface area compared to the PCL frame alone. The increased specific surface area in the collagen-PCL composite promoted increased initial attachment of porcine adipose derived stem cells versus the PCL construct. Copyright © 2016 Elsevier Ltd. All rights reserved.

The effects of facial color and inversion on the N170 event-related potential (ERP) component.

PubMed

Minami, T; Nakajima, K; Changvisommid, L; Nakauchi, S

2015-12-17

Faces are important for social interaction because much can be perceived from facial details, including a person's race, age, and mood. Recent studies have shown that both configural (e.g. face shape and inversion) and surface information (e.g. surface color and reflectance properties) are important for face perception. Therefore, the present study examined the effects of facial color and inverted face properties on event-related potential (ERP) responses, particularly the N170 component. Stimuli consisted of natural and bluish-colored faces. Faces were presented in both upright and upside down orientations. An ANOVA was used to analyze N170 amplitudes and verify the effects of the main independent variables. Analysis of N170 amplitude revealed the significant interactions between stimulus orientation and color. Subsequent analysis indicated that N170 was larger for bluish-colored faces than natural-colored faces, and N170 to natural-colored faces was larger in response to inverted stimulus as compared to upright stimulus. Additionally, a multivariate pattern analysis (MVPA) investigated face-processing dynamics without any prior assumptions. Results distinguished, above chance, both facial color and orientation from single-trial electroencephalogram (EEG) signals. Decoding performance for color classification of inverted faces was significantly diminished as compared to an upright orientation. This suggests that processing orientation is predominant over facial color. Taken together, the present findings elucidate the temporal and spatial distribution of orientation and color processing during face processing. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

The effect of surfactant-free TiO2 surface hydroxyl groups on physicochemical, optical and self-cleaning properties of developed coatings on polycarbonate

NASA Astrophysics Data System (ADS)

Yaghoubi, H.; Dayerizadeh, A.; Han, S.; Mulaj, M.; Gao, W.; Li, X.; Muschol, M.; Ma, S.; Takshi, A.

2013-12-01

TiO2 is a prototypical transition metal oxide with physicochemical properties that can be modified more readily through sol-gel synthesis than through other techniques. Herein, we report on the change in the density of the hydroxyl groups on the surface of synthesized surfactant-free TiO2 nanoparticles in water due to varying the pH (7.3, 8.3, 9.3 and 10.3) of the peroxotitanium complex, i.e. the amorphous sol, prior to refluxing. This resulted in colloidal solutions with differing crystallinity, nanoparticle size, optical indirect bandgaps and photocatalytic activity. It was shown that increasing the density of hydroxyl groups on TiO2 particles coupled with low-temperature annealing (90 °C) induced an anatase to rutile transformation. Increasing the pH of the peroxotitanium complex interrupted the formation of anatase phase in crystalline sol, as evidenced by intensity increases of the Raman bands at ˜822 (Ti-O-H) and 906 cm-1 (vibrational Ti-O-H) and an intensity decrease of the band at 150 cm-1 (anatase photonic Eg). Films prepared from higher pH suspensions showed lower roughness. The reaction rate constants for photo-induced self-cleaning activity of TiO2 films prepared from colloidal solutions at pH 7.3, 8.3, 9.3 and 10.3 were estimated at 0.017 s-1, 0.014 s-1, 0.007 s-1 and 0.006 s-1, respectively.

Mechanical Properties of Degraded PMR-15 Resin

NASA Technical Reports Server (NTRS)

Tsuji, Luis C.

2000-01-01

Thermo-oxidative aging produces a nonuniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316 C in either air or nitrogen, for durations of up to 800 hr. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and coefficient of thermal expansion (CTE) of nitrogen aged specimens were measured directly. The nitrogen-aged specimens were assumed to have the same properties as the interior material in the air-aged specimens. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.

Anion Solvation in Carbonate-Based Electrolytes

DOE PAGES

von Wald Cresce, Arthur; Gobet, Mallory; Borodin, Oleg; ...

2015-11-16

The correlation between Li + solvation and interphasial chemistry on anodes firmly established in Li-ion batteries, the effect of cation–solvent interaction has gone beyond bulk thermodynamic and transport properties and become an essential element that determines the reversibility of electrochemistry and kinetics of Li-ion intercalation chemistries. Now, most studies are dedicated to the solvation of Li +, and the solvation of anions in carbonate-based electrolytes and its possible effect on the electrochemical stability of such electrolytes remains little understood. Moreover, as a mirror effort to prior Li + solvation studies, this work focuses on the interactions between carbonate-based solvents andmore » two anions (hexafluorophosphate, PF 6–, and tetrafluoroborate, BF 4–) that are most frequently used in Li-ion batteries. The possible correlation between such interaction and the interphasial chemistry on cathode surface is also explored.« less

Using ion exchange chromatography to purify a recombinantly expressed protein.

PubMed

Duong-Ly, Krisna C; Gabelli, Sandra B

2014-01-01

Ion exchange chromatography (IEX) separates molecules by their surface charge, a property that can vary vastly between different proteins. There are two types of IEX, cation exhange and anion exchange chromatography. The protocol that follows was designed by the authors for anion exchange chromatography of a recombinantly expressed protein having a pI of 4.9 and containing two cysteine residues and one tryptophan residue, using an FPLC system. Prior to anion exchange, the protein had been salted out using ammonium sulfate precipitation and partially purified via hydrophobic interaction chromatography (see Salting out of proteins using ammonium sulfate precipitation and Use and Application of Hydrophobic Interaction Chromatography for Protein Purification). Slight modifications to this protocol may be made to accommodate both the protein of interest and the availability of equipment. © 2014 Elsevier Inc. All rights reserved.

Influence of structural parameters on the tendency of VVER-1000 reactor pressure vessel steel to temper embrittlement

NASA Astrophysics Data System (ADS)

Gurovich, B.; Kuleshova, E.; Zabusov, O.; Fedotova, S.; Frolov, A.; Saltykov, M.; Maltsev, D.

2013-04-01

In this paper the influence of structural parameters on the tendency of steels to reversible temper embrittlement was studied for assessment of performance properties of reactor pressure vessel steels with extended service life. It is shown that the growth of prior austenite grain size leads to an increase of the critical embrittlement temperature in the initial state. An embrittlement heat treatment at the temperature of maximum manifestation of temper embrittlement (480 °C) shifts critical embrittlement temperature to higher values due to the increase of the phosphorus concentration on grain boundaries. There is a correlation between phosphorus concentration on boundaries of primary austenite grains and the share of brittle intergranular fracture (that, in turn, depends on impact test temperature) in the fracture surfaces of the tested Charpy specimens.

Carbohydrate Cluster Microarrays Fabricated on 3-Dimensional Dendrimeric Platforms for Functional Glycomics Exploration

PubMed Central

Zhou, Xichun; Turchi, Craig; Wang, Denong

2009-01-01

We reported here a novel, ready-to-use bioarray platform and methodology for construction of sensitive carbohydrate cluster microarrays. This technology utilizes a 3-dimensional (3-D) poly(amidoamine) starburst dendrimer monolayer assembled on glass surface, which is functionalized with terminal aminooxy and hydrazide groups for site-specific coupling of carbohydrates. A wide range of saccharides, including monosaccharides, oligosaccharides and polysaccharides of diverse structures, are applicable for the 3-D bioarray platform without prior chemical derivatization. The process of carbohydrate coupling is effectively accelerated by microwave radiation energy. The carbohydrate concentration required for microarray fabrication is substantially reduced using this technology. Importantly, this bioarray platform presents sugar chains in defined orientation and cluster configurations. It is, thus, uniquely useful for exploration of the structural and conformational diversities of glyco-epitope and their functional properties. PMID:19791771

On the sputter alteration of regoliths of outer solar system bodies

NASA Technical Reports Server (NTRS)

Hapke, B.

1986-01-01

The present theoretical and experimental consideration of processes that are expected to occur when the porous regoliths on outer solar system bodies lacking atmospheres are subjected to energetic ion bombardment indicates that porosity reduces the effective sputtering yield of a soil by more than an order of magnitude. Between 90 and 97 percent of the sputtered atoms are trapped within the regolith and subjected to differential desorption fractionation, which emerges as the most important path for the alteration of chemical and optical properties in sputtered regoliths. Sputtered porous mixtures of water, ammonia and methane frosts suffer a loss of H, and surface reactions of C, N, and O that should yield complex hydrocarbons and carbohydrates; such reactions may have played a role in the formation of carbonaceous chondrites' matrix material prior to agglomeration.

Hall-effect Thruster Channel Surface Properties Investigation (PREPRINT)

DTIC Science & Technology

2011-03-03

Article 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Hall-effect Thruster Channel Surface Properties Investigation 5b...13. SUPPLEMENTARY NOTES For publication in the AIAA Journal of Propulsion and Power. 14. ABSTRACT Surface properties of Hall-effect thruster...incorporated into thruster simulations, and these models must account for evolution of channel surface properties due to thruster operation. Results from

Surface engineering on CeO2 nanorods by chemical redox etching and their enhanced catalytic activity for CO oxidation

NASA Astrophysics Data System (ADS)

Gao, Wei; Zhang, Zhiyun; Li, Jing; Ma, Yuanyuan; Qu, Yongquan

2015-07-01

Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce3+ fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications.Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce3+ fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications. Electronic supplementary information (ESI) available: Diameter distributions of as-prepared and etched samples, optical images, specific catalytic data of CO oxidation and comparison of CO oxidation. See DOI: 10.1039/c5nr01846c

Digitized locksmith forensics: automated detection and segmentation of toolmarks on highly structured surfaces

NASA Astrophysics Data System (ADS)

Clausing, Eric; Vielhauer, Claus

2014-02-01

Locksmith forensics is an important area in crime scene forensics. Due to new optical, contactless, nanometer range sensing technology, such traces can be captured, digitized and analyzed more easily allowing a complete digital forensic investigation. In this paper we present a significantly improved approach for the detection and segmentation of toolmarks on surfaces of locking cylinder components (using the example of the locking cylinder component 'key pin') acquired by a 3D Confocal Laser Scanning Microscope. This improved approach is based on our prior work1 using a block-based classification approach with textural features. In this prior work1 we achieve a solid detection rate of 75-85% for the detection of toolmarks originating from illegal opening methods. Here, in this paper we improve, expand and fuse this prior approach with additional features from acquired surface topography data, color data and an image processing approach using adapted Gabor filters. In particular we are able of raising the detection and segmentation rates above 90% with our test set of 20 key pins with approximately 700 single toolmark traces of four different opening methods. We can provide a precise pixel- based segmentation as opposed to the rather imprecise segmentation of our prior block-based approach and as the use of the two additional data types (color and especially topography) require a specific pre-processing, we furthermore propose an adequate approach for this purpose.

Surface Characterization of Polymer Blends by XPS and ToF-SIMS

PubMed Central

Chan, Chi Ming; Weng, Lu-Tao

2016-01-01

The surface properties of polymer blends are important for many industrial applications. The physical and chemical properties at the surface of polymer blends can be drastically different from those in the bulk due to the surface segregation of the low surface energy component. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary mass spectrometry (ToF-SIMS) have been widely used to characterize surface and bulk properties. This review provides a brief introduction to the principles of XPS and ToF-SIMS and their application to the study of the surface physical and chemical properties of polymer blends. PMID:28773777

TREATMENT OF URANIUM SURFACES

DOEpatents

Slunder, C.J.

1959-02-01

An improved process is presented for prcparation of uranium surfaces prior to electroplating. The surfacc of the uranium to be electroplated is anodized in a bath comprising a solution of approximately 20 to 602 by weight of phosphoric acid which contains about 20 cc per liter of concentrated hydrochloric acid. Anodization is carried out for approximately 20 minutes at a current density of about 0.5 amperes per square inch at a temperature of about 35 to 45 C. The oxidic film produced by anodization is removed by dipping in strong nitric acid, followed by rinsing with water just prior to electroplating.

TREATMENT OF METALS PRIOR TO ELECTROPLATING

DOEpatents

Huddle, R.A.U.; Flint, O.

1958-05-20

The preparation of certain metal surfaces to receive electrodeposits is described. Surfaces of the metals are subjected to shot blasting by ferrous metal shot, and the surfaces then are given a coating of copper by displacement from a copper salt solution. The method applies to U, Zr, Ti, Ta, Ni, Mo, W, and V.

Environmental Report on the Northwest Pacific for the Marine Seismic System (MSS)

DTIC Science & Technology

1980-12-01

Kuroshio Cur rent is I oca t ed. F. Surface Currents Surface current circulation in the Northwest Pacific consists of the eastward-flowing warm water...overlying surface waters back to early late Miocene time. Prior to this, and through the Oligocene , the seamount was buried beneath a nearly equally

Bondable Stainless Surface Coats Protect Against Rust

NASA Technical Reports Server (NTRS)

Davis, G. D.; Shaffer, D. K.; Clearfield, H. M.; Nagle, D.; Groff, G.

1995-01-01

Report describes tests conducted to assess use of bondable stainless surface (BOSS) coating materials to protect steel cases of solid-fuel rocket motors against corrosion and to provide surface microstructure and chemistry suitable for bonding to insulating material. Eliminates need to cover cases with grease to prevent corrosion and degreasing immediately prior to use.

Development and Validation of the Implicit Information from Lewis Structures Instrument(IILSI): Do Students Connect Structures with Properties?

ERIC Educational Resources Information Center

Cooper, Melanie M.; Underwood, Sonia M.; Hilley, Caleb Z.

2012-01-01

Lewis structures are a simplified two dimensional "cartoon" of molecular structure that allow a knowledgeable user to predict the types of properties a particular substance may exhibit. However, prior research shows that many students fail to recognize these structure-property connections and are unable to decode the information…

41 CFR 102-75.1015 - Are there any restrictions on Federal agencies concerning property donations to public bodies?

Code of Federal Regulations, 2010 CFR

2010-07-01

... restrictions on Federal agencies concerning property donations to public bodies? 102-75.1015 Section 102-75... Donation to Public Bodies Restrictions § 102-75.1015 Are there any restrictions on Federal agencies concerning property donations to public bodies? Yes, Federal agencies must obtain prior concurrence of GSA...

41 CFR 102-75.1015 - Are there any restrictions on Federal agencies concerning property donations to public bodies?

Code of Federal Regulations, 2012 CFR

2012-01-01

... restrictions on Federal agencies concerning property donations to public bodies? 102-75.1015 Section 102-75... Donation to Public Bodies Restrictions § 102-75.1015 Are there any restrictions on Federal agencies concerning property donations to public bodies? Yes, Federal agencies must obtain prior concurrence of GSA...

41 CFR 102-75.1015 - Are there any restrictions on Federal agencies concerning property donations to public bodies?

Code of Federal Regulations, 2014 CFR

2014-01-01

... restrictions on Federal agencies concerning property donations to public bodies? 102-75.1015 Section 102-75... Donation to Public Bodies Restrictions § 102-75.1015 Are there any restrictions on Federal agencies concerning property donations to public bodies? Yes, Federal agencies must obtain prior concurrence of GSA...

41 CFR 102-75.1015 - Are there any restrictions on Federal agencies concerning property donations to public bodies?

Code of Federal Regulations, 2013 CFR

2013-07-01

... restrictions on Federal agencies concerning property donations to public bodies? 102-75.1015 Section 102-75... Donation to Public Bodies Restrictions § 102-75.1015 Are there any restrictions on Federal agencies concerning property donations to public bodies? Yes, Federal agencies must obtain prior concurrence of GSA...

41 CFR 102-75.1015 - Are there any restrictions on Federal agencies concerning property donations to public bodies?

Code of Federal Regulations, 2011 CFR

2011-01-01

... restrictions on Federal agencies concerning property donations to public bodies? 102-75.1015 Section 102-75... Donation to Public Bodies Restrictions § 102-75.1015 Are there any restrictions on Federal agencies concerning property donations to public bodies? Yes, Federal agencies must obtain prior concurrence of GSA...

Capitalization of Charter Schools into Residential Property Values. Working Paper #46

ERIC Educational Resources Information Center

Imberman, Scott; Naretta, Michael; O'Rourke, Margaret

2015-01-01

While prior research has found clear impacts of schools and school quality on property values, little is known about whether charter schools have similar effects. Using sale price data for residential properties in Los Angeles County from 2008 to 2011 we estimate the neighborhood level impact of charter schools on housing prices. Using an…

Making Connections in Math: Activating a Prior Knowledge Analogue Matters for Learning

ERIC Educational Resources Information Center

Sidney, Pooja G.; Alibali, Martha W.

2015-01-01

This study investigated analogical transfer of conceptual structure from a prior-knowledge domain to support learning in a new domain of mathematics: division by fractions. Before a procedural lesson on division by fractions, fifth and sixth graders practiced with a surface analogue (other operations on fractions) or a structural analogue (whole…

Mechanical Properties of Degraded PMR-15 Resin

NASA Technical Reports Server (NTRS)

Tsuji, Luis C.; McManus, Hugh L.; Bowles, Kenneth J.

1998-01-01

Thermo-oxidative aging produces a non-uniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316 C in either air or nitrogen, for durations of up to 800 hours. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and Coefficient of Thermal Expansion (CTE) of nitrogen aged specimens were measured directly. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.

Modeling electrochemical resistance with coal surface properties in a direct carbon fuel cell based on molten carbonate

NASA Astrophysics Data System (ADS)

Eom, Seongyong; Ahn, Seongyool; Kang, Kijoong; Choi, Gyungmin

2017-12-01

In this study, a numerical model of activation and ohmic polarization is modified, taking into account the correlation function between surface properties and inner resistance. To investigate the correlation function, the surface properties of coal are changed by acid treatment, and the correlations between the inner resistance measured by half-cell tests and the surface characteristics are analyzed. A comparison between the model and experimental results demonstrates that the absolute average deviations for each fuel are less than 10%. The numerical results show that the sensitivities of the coal surface properties affecting polarization losses change depending on the operating temperature. The surface oxygen concentrations affect the activation polarization and the sensitivity decreased with increasing temperature. The surface ash of coal is an additional index to be considered along with ohmic polarization and it has the greatest effect on the surface properties at 973 K.

Properties that influence the specific surface areas of carbon nanotubes and nanofibers.

PubMed

Birch, M Eileen; Ruda-Eberenz, Toni A; Chai, Ming; Andrews, Ronnee; Hatfield, Randal L

2013-11-01

Commercially available carbon nanotubes and nanofibers were analyzed to examine possible relationships between their Brunauer-Emmett-Teller specific surface areas (SSAs) and their physical and chemical properties. Properties found to influence surface area were number of walls/diameter, impurities, and surface functionalization with hydroxyl and carboxyl groups. Characterization by electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric analysis, and elemental analysis indicates that SSA can provide insight on carbon nanomaterials properties, which can differ vastly depending on synthesis parameters and post-production treatments. In this study, how different properties may influence surface area is discussed. The materials examined have a wide range of surface areas. The measured surface areas differed from product specifications, to varying degrees, and between similar products. Findings emphasize the multiple factors that influence surface area and mark its utility in carbon nanomaterial characterization, a prerequisite to understanding their potential applications and toxicities. Implications for occupational monitoring are discussed.

Surface pre-conditioning with bioactive glass air-abrasion can enhance enamel white spot lesion remineralization.

PubMed

Milly, Hussam; Festy, Frederic; Andiappan, Manoharan; Watson, Timothy F; Thompson, Ian; Banerjee, Avijit

2015-05-01

To evaluate the effect of pre-conditioning enamel white spot lesion (WSL) surfaces using bioactive glass (BAG) air-abrasion prior to remineralization therapy. Ninety human enamel samples with artificial WSLs were assigned to three WSL surface pre-conditioning groups (n=30): (a) air-abrasion with BAG-polyacrylic acid (PAA-BAG) powder, (b) acid-etching using 37% phosphoric acid gel (positive control) and (c) unconditioned (negative control). Each group was further divided into three subgroups according to the following remineralization therapy (n=10): (I) BAG paste (36 wt.% BAG), (II) BAG slurry (100 wt.% BAG) and (III) de-ionized water (negative control). The average surface roughness and the lesion step height compared to intra-specimen sound enamel reference points were analyzed using non-contact profilometry. Optical changes within the lesion subsurface compared to baseline scans were assessed using optical coherence tomography (OCT). Knoop microhardness evaluated the WSLs' mechanical properties. Raman micro-spectroscopy measured the v-(CO3)(2-)/v1-(PO4)(3-) ratio. Structural changes in the lesion were observed using confocal laser scanning microscopy (CLSM) and scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX). All comparisons were considered statistically significant if p<0.05. PAA-BAG air-abrasion removed 5.1 ± 0.6 μm from the lesion surface, increasing the WSL surface roughness. Pre-conditioning WSL surfaces with PAA-BAG air-abrasion reduced subsurface light scattering, increased the Knoop microhardness and the mineral content of the remineralized lesions (p<0.05). SEM-EDX revealed mineral depositions covering the lesion surface. BAG slurry resulted in a superior remineralization outcome, when compared to BAG paste. Pre-conditioning WSL surfaces with PAA-BAG air-abrasion modified the lesion surface physically and enhanced remineralization using BAG 45S5 therapy. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Mammalian enamel maturation: Crystallographic changes prior to tooth eruption

PubMed Central

Kallistová, Anna; Horáček, Ivan; Šlouf, Miroslav; Skála, Roman; Fridrichová, Michaela

2017-01-01

Using the distal molar of a minipig as a model, we studied changes in the microstructural characteristics of apatite crystallites during enamel maturation (16-23 months of postnatal age), and their effects upon the mechanical properties of the enamel coat. The slow rate of tooth development in a pig model enabled us to reveal essential heterochronies in particular components of the maturation process. The maturation changes began along the enamel-dentine junction (EDJ) of the trigonid, spreading subsequently to the outer layers of the enamel coat to appear at the surface zone with a 2-month delay. Correspondingly, at the distal part of the tooth the timing of maturation processes is delayed by 3-5 month compared to the mesial part of the tooth. The early stage of enamel maturation (16-20 months), when the enamel coat is composed almost exclusively of radial prismatic enamel, is characterized by a gradual increase in crystallite thickness (by a mean monthly increment of 3.8 nm); and an increase in the prism width and thickness of crystals composed of elementary crystallites. The late stage of maturation (the last two months prior to tooth eruption), marked with the rapid appearance of the interprismatic matrix (IPM) during which the crystals densely infill spaces between prisms, is characterized by an abrupt decrease in microstrain and abrupt changes in the micromechanical properties of the enamel: a rapid increase in its ability to resist long-term load and its considerable hardening. The results suggest that in terms of crystallization dynamics the processes characterizing the early and late stage of mammalian enamel maturation represent distinct entities. In regards to common features with enamel formation in the tribosphenic molar we argue that the separation of these processes could be a common apomorphy of mammalian amelogenetic dynamics in general. PMID:28196135

Mammalian enamel maturation: Crystallographic changes prior to tooth eruption.

PubMed

Kallistová, Anna; Horáček, Ivan; Šlouf, Miroslav; Skála, Roman; Fridrichová, Michaela

2017-01-01

Using the distal molar of a minipig as a model, we studied changes in the microstructural characteristics of apatite crystallites during enamel maturation (16-23 months of postnatal age), and their effects upon the mechanical properties of the enamel coat. The slow rate of tooth development in a pig model enabled us to reveal essential heterochronies in particular components of the maturation process. The maturation changes began along the enamel-dentine junction (EDJ) of the trigonid, spreading subsequently to the outer layers of the enamel coat to appear at the surface zone with a 2-month delay. Correspondingly, at the distal part of the tooth the timing of maturation processes is delayed by 3-5 month compared to the mesial part of the tooth. The early stage of enamel maturation (16-20 months), when the enamel coat is composed almost exclusively of radial prismatic enamel, is characterized by a gradual increase in crystallite thickness (by a mean monthly increment of 3.8 nm); and an increase in the prism width and thickness of crystals composed of elementary crystallites. The late stage of maturation (the last two months prior to tooth eruption), marked with the rapid appearance of the interprismatic matrix (IPM) during which the crystals densely infill spaces between prisms, is characterized by an abrupt decrease in microstrain and abrupt changes in the micromechanical properties of the enamel: a rapid increase in its ability to resist long-term load and its considerable hardening. The results suggest that in terms of crystallization dynamics the processes characterizing the early and late stage of mammalian enamel maturation represent distinct entities. In regards to common features with enamel formation in the tribosphenic molar we argue that the separation of these processes could be a common apomorphy of mammalian amelogenetic dynamics in general.

Confidence set inference with a prior quadratic bound

NASA Technical Reports Server (NTRS)

Backus, George E.

1988-01-01

In the uniqueness part of a geophysical inverse problem, the observer wants to predict all likely values of P unknown numerical properties z = (z sub 1,...,z sub p) of the earth from measurement of D other numerical properties y(0)=(y sub 1(0),...,y sub D(0)) knowledge of the statistical distribution of the random errors in y(0). The data space Y containing y(0) is D-dimensional, so when the model space X is infinite-dimensional the linear uniqueness problem usually is insoluble without prior information about the correct earth model x. If that information is a quadratic bound on x (e.g., energy or dissipation rate), Bayesian inference (BI) and stochastic inversion (SI) inject spurious structure into x, implied by neither the data nor the quadratic bound. Confidence set inference (CSI) provides an alternative inversion technique free of this objection. CSI is illustrated in the problem of estimating the geomagnetic field B at the core-mantle boundary (CMB) from components of B measured on or above the earth's surface. Neither the heat flow nor the energy bound is strong enough to permit estimation of B(r) at single points on the CMB, but the heat flow bound permits estimation of uniform averages of B(r) over discs on the CMB, and both bounds permit weighted disc-averages with continous weighting kernels. Both bounds also permit estimation of low-degree Gauss coefficients at the CMB. The heat flow bound resolves them up to degree 8 if the crustal field at satellite altitudes must be treated as a systematic error, but can resolve to degree 11 under the most favorable statistical treatment of the crust. These two limits produce circles of confusion on the CMB with diameters of 25 deg and 19 deg respectively.

Enhancement of the fatigue performance of Ti-6Al-4V implant products

NASA Astrophysics Data System (ADS)

Wimalasiri, Dematapaksha H. R. J.

Implants surgery, in particular hip implants, is fast becoming a routine, popular approach for curing diseases such as, osteoarthritis and rheumatic arthritis. However one potential problem with the insertion of a metal implant is that of the risk of fatigue failure. Numerous factors affect the propensity of a metal to fatigue, none more so than the physical and stress state of the surface. This research is focused on an assessment of the role of manufacturing processes on the fatigue performance of hip implants made from a Ti-6Al-4V alloy. The role of surface defects, surface residual stresses and material microstructural properties which influence fatigue performance were examined. Characterization of the implant material and of the processes involved in actual hip implant manufacturing were conducted. Rotating bend fatigue testing using hour glass shaped specimens was conducted to evaluate the fatigue performance at selected manufacturing stages. The surface roughness/defects and residual stresses were measured prior to conducting fatigue tests. A variation of fatigue limit, attributed to variations of surface roughness and surface residual stress was observed. The influence of parameters such as, stress ratio and mean stress effect, variation of fracture mechanics parameters (e.g. DeltaK[th]) and the limiting threshold conditions for different stages of cracks were investigated in the context of Kitagawa-Takahashi (K-T) type diagrams. Experimental data was used to develop models which were used to calculate, (i). fatigue life at respective stress amplitude and, (ii). the fatigue limit of components with known surface roughness/defect size and residual stress. To evaluate material crack growth properties a surface replication method was used. The output from both models showed good correlation with experimental data. Comprehensive fractography was conducted using optical, secondary electron, and infinite focus microscopy to support the results obtained from fatigue testing. Analysis was performed on in-vivo hip implant failure data covering the last 12 years. Fatigue failures occur in two locations on the implant stem, namely the cone area and the neck area. These two locations were investigated separately to identify the factors, such as; the category of implant most vulnerable to failure, service life, design features, fixation with the host bone, crack initiation features and propagation details. An attempt was made to compare in-vivo fatigue features with experimental fatigue results. X-ray diffraction (XRD) was used to investigate the surface residual stresses resulting from different manufacturing processes. The results were confirmed and software and hardware settings were calibrated in accordance with the results obtained from XRD analysis conducted at National Physical Laboratories (NPL), UK. Surface roughness measurements were also conducted using stylus type surface profilometer. The knowledge gained from this research can be used to understand the causes and modes of in-vivo fatigue failure of hip implants made of Ti-6Al-4V. Understanding the fatigue/mechanical properties of the implant material enables recommendations and optimization of good practice in manufacturing to eliminate in-vivo fatigue failures.

A novel method to measure skin mechanical properties with three-dimensional digital image correlation.

PubMed

Xu, Z; Dela Cruz, J; Fthenakis, C; Saliou, C

2018-06-06

Measuring skin mechanical properties has been of great interest in the skincare industry. It is a high accuracy and non-invasive optical technique which quantitatively tracks skin movement and deformation under mechanical perturbations. A study was conducted with female subjects (25-65 years old). A refined speckle pattern applied onto the skin surface was used for DIC measurements. A unidirectional force pulled the skin at a constant velocity, while the deformation process was quantified by the DIC. Prior to the DIC measurement, Cutometer ® readings were taken on the same area. The DIC protocol's reproducibility across multiple pattern applications, the measurement's repeatability, and the sensitivity in differentiating skin mechanical properties were investigated. Subjects were clustered with statistical significance according to their skin mechanical properties described by six DIC metrics (μ [major strain], σ [major strain], μ [minor strain], σ [minor strain], μ [displacement], and σ [displacement]). Most measurement random errors are below 6%. This is several folds smaller in magnitude than the difference in the mean response between the clusters. Several Cutometer ® parameters also showed good agreement with μ (displacement). DIC was able to differentiate skins of different mechanical qualities. We also proposed the physical significance of the DIC metrics. Some of the DIC metrics potentially offer new insights into skin mechanical properties that complement those revealed by conventional instruments. Accurate measurements, large measurement areas along with ease of direct visualization are substantial advantages of DIC. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Sediment entrainment by debris flows: In situ measurements from the headwaters of a steep catchment

USGS Publications Warehouse

McCoy, S.W.; Kean, Jason W.; Coe, Jeffrey A.; Tucker, G.E.; Staley, Dennis M.; Wasklewicz, T.A.

2012-01-01

Debris flows can dramatically increase their volume, and hence their destructive potential, by entraining sediment. Yet quantitative constraints on rates and mechanics of sediment entrainment by debris flows are limited. Using an in situ sensor network in the headwaters of a natural catchment we measured flow and bed properties during six erosive debris-flow events. Despite similar flow properties and thicknesses of bed sediment entrained across all events, time-averaged entrainment rates were significantly faster for bed sediment that was saturated prior to flow arrival compared with rates for sediment that was dry. Bed sediment was entrained from the sediment-surface downward in a progressive fashion and occurred during passage of dense granular fronts as well as water-rich, inter-surge flow.En massefailure of bed sediment along the sediment-bedrock interface was never observed. Large-magnitude, high-frequency fluctuations in total normal basal stress were dissipated within the upper 5 cm of bed sediment. Within this near surface layer, concomitant fluctuations in Coulomb frictional resistance are expected, irrespective of the influence of pore fluid pressure or fluctuations in shear stress. If the near-surface sediment was wet as it was overridden by a flow, additional large-magnitude, high-frequency pore pressure fluctuations were measured in the near-surface bed sediment. These pore pressure fluctuations propagated to depth at subsonic rates and in a diffusive manner. The depth to which large excess pore pressures propagated was typically less than 10 cm, but scaled as (D/fi)0.5, in which D is the hydraulic diffusivity and fi is the frequency of a particular pore pressure fluctuation. Shallow penetration depths of granular-normal-stress fluctuations and excess pore pressures demonstrate that only near-surface bed sediment experiences the full dynamic range of effective-stress fluctuations, and as a result, can be more easily entrained than deeper sediment. These data provide robust tests for mechanical models of entrainment and demonstrate that a debris flow over wet bed sediment will be larger than the same flow over dry bed sediment.

Fracture surface analysis in composite and titanium bonding

NASA Technical Reports Server (NTRS)

Devilbiss, T. A.; Wightman, J. P.

1985-01-01

To understand the mechanical properties of fiber-reinforced composite materials, it is necessary to understand the mechanical properties of the matrix materials and of the reinforcing fibers. Another factor that can affect the mechanical properties of a composite material is the interaction between the fiber and the matrix. In general, composites with strong fiber matrix bonding will give higher modulus, lower toughness composites. Composites with weak bonding will have a lower modulus and more ductility. The situation becomes a bit more complex when all possibilities are examined. To be considered are the following: the properties of the surface layer on the fiber, the interactive forces between polymer and matrix, the surface roughness and porosity of the fiber, and the morphology of the matrix polymer at the fiber surface. In practice, the surface of the fibers is treated to enhance the mechanical properties of a composite. These treatments include anodization, acid etching, high temperature oxidation, and plasma oxidation, to name a few. The goal is to be able to predict the surface properties of carbon fibers treated in various ways, and then to relate surface properties to fiber matrix bonding.

Effects of Thermal and Pressure Histories on the Chemical Strengthening of Sodium Aluminosilicate Glass

NASA Astrophysics Data System (ADS)

Svenson, Mouritz; Thirion, Lynn; Youngman, Randall; Mauro, John; Bauchy, Mathieu; Rzoska, Sylwester; Bockowski, Michal; Smedskjaer, Morten

2016-03-01

Glasses can be chemically strengthened through the ion exchange process, wherein smaller ions in the glass (e.g., Na+) are replaced by larger ions from a salt bath (e.g., K+). This develops a compressive stress (CS) on the glass surface, which, in turn, improves the damage resistance of the glass. The magnitude and depth of the generated CS depends on the thermal and pressure histories of the glass prior to ion exchange. In this study, we investigate the ion exchange-related properties (mutual diffusivity, CS, and hardness) of a sodium aluminosilicate glass, which has been densified through annealing below the initial fictive temperature of the glass or through pressure-quenching from the glass transition temperature at 1 GPa prior to ion exchange. We show that the rate of alkali interdiffusivity depends only on the density of the glass, rather than on the applied densification method. However, we also demonstrate that for a given density, the increase in CS and increase in hardness induced by ion exchange strongly depends on the densification method. Specifically, at constant density, the CS and hardness values achieved through thermal annealing are larger than those achieved through pressure-quenching. These results are discussed in relation to the structural changes in the environment of the network-modifier and the overall network densification.

Modulation of dry tribological property of stainless steel by femtosecond laser surface texturing

NASA Astrophysics Data System (ADS)

Wang, Zhuo; Zhao, Quanzhong; Wang, Chengwei; Zhang, Yang

2015-06-01

We reported on the modification of tribological properties of stainless steel by femtosecond laser surface microstructuring. Regular arranged micro-grooved textures with different spacing were produced on the AISI 304L steel surfaces by an 800-nm femtosecond laser. The tribological properties of smooth surface and textured surface were investigated by carrying out reciprocating ball-on-flat tests against Al2O3 ceramic balls under dry friction. Results show that the spacing of micro-grooves had a significant impact on friction coefficient of textured surfaces. Furthermore, the wear behaviors of smooth and textured surface were also investigated. Femtosecond laser surface texturing had a marked potential for modulating friction and wear properties if the micro-grooves were distributed in an appropriate manner.

Crack Growth Mechanisms under Anti-Plane Shear in Composite Laminates

NASA Astrophysics Data System (ADS)

Horner, Allison Lynne

The research conducted for this dissertation focuses on determining the mechanisms associated with crack growth in polymer matrix composite laminates subjected to anti-plane shear (mode III) loading. For mode III split-beam test methods were proposed, and initial evaluations were conducted. A single test method was selected for further evaluation. Using this test method, it was determined that the apparent mode III delamination toughness, GIIIc , depended on geometry, which indicated a true material property was not being measured. Transverse sectioning and optical microscopy revealed an array of transverse matrix cracks, or echelon cracks, oriented at approximately 45° and intersecting the plane of the delamination. Subsequent investigations found the echelon array formed prior to the onset of planar delamination advance and that growth of the planar delamination is always coupled to echelon array formation in these specimens. The evolution of the fracture surfaces formed by the echelon array and planar delamination were studied, and it was found that the development was similar to crack growth in homogenous materials subjected to mode III or mixed mode I-III loading, although the composite laminate architecture constrained the fracture surface development differently than homogenous materials. It was also found that, for split-beam specimens such as those used herein, applying an anti-plane shear load results in twisting of the specimen's uncracked region which gives rise to a mixed-mode I-III load condition. This twisting has been related to the apparent mode III toughness as well as the orientation of the transverse matrix cracks. A finite element model was then developed to study the mechanisms of initial echelon array formation. From this, it is shown that an echelon array will develop, but will become self-limiting prior to the onset of planar delamination growth.

Semiautomatic and Automatic Cooperative Inversion of Seismic and Magnetotelluric Data

NASA Astrophysics Data System (ADS)

Le, Cuong V. A.; Harris, Brett D.; Pethick, Andrew M.; Takam Takougang, Eric M.; Howe, Brendan

2016-09-01

Natural source electromagnetic methods have the potential to recover rock property distributions from the surface to great depths. Unfortunately, results in complex 3D geo-electrical settings can be disappointing, especially where significant near-surface conductivity variations exist. In such settings, unconstrained inversion of magnetotelluric data is inexorably non-unique. We believe that: (1) correctly introduced information from seismic reflection can substantially improve MT inversion, (2) a cooperative inversion approach can be automated, and (3) massively parallel computing can make such a process viable. Nine inversion strategies including baseline unconstrained inversion and new automated/semiautomated cooperative inversion approaches are applied to industry-scale co-located 3D seismic and magnetotelluric data sets. These data sets were acquired in one of the Carlin gold deposit districts in north-central Nevada, USA. In our approach, seismic information feeds directly into the creation of sets of prior conductivity model and covariance coefficient distributions. We demonstrate how statistical analysis of the distribution of selected seismic attributes can be used to automatically extract subvolumes that form the framework for prior model 3D conductivity distribution. Our cooperative inversion strategies result in detailed subsurface conductivity distributions that are consistent with seismic, electrical logs and geochemical analysis of cores. Such 3D conductivity distributions would be expected to provide clues to 3D velocity structures that could feed back into full seismic inversion for an iterative practical and truly cooperative inversion process. We anticipate that, with the aid of parallel computing, cooperative inversion of seismic and magnetotelluric data can be fully automated, and we hold confidence that significant and practical advances in this direction have been accomplished.

26 CFR 20.2056A-7 - Allowance of prior transfer credit under section 2013.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 2013. 20.2056A-7 Section 20.2056A-7 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE... Taxable Estate § 20.2056A-7 Allowance of prior transfer credit under section 2013. (a) Property subject to QDOT election. Section 2056(d)(3) provides special rules for computing the section 2013 credit allowed...

Treatment of hides with tara-modified protein products

USDA-ARS?s Scientific Manuscript database

In prior research, we demonstrated that gelatin could be modified with quebracho to produce products whose physicochemical properties would enable them to be used effectively as fillers in leather processing, and that leather resulting from this treatment had improved subjective properties with litt...

Study on the Toughness of X100 Pipeline Steel Heat Affected Zone

NASA Astrophysics Data System (ADS)

Li, Xueda; Shang, Chengjia; Ma, Xiaoping; Subramanian, S. V.

Microstructure-property correlation of heat affected zone (HAZ) in X100 longitudinal submerged arc welding (LSAW) real weld joint was studied in this paper. Coarse grained (CG) HAZ and intercritically reheated coarse grained (ICCG) HAZ were characterized by optical microscope (OM), electron backscattered diffraction (EBSD). The microstructure of CGHAZ is mostly composed of granular bainite with low density of high angle boundaries (HAB). Prior austenite grain size is 80μm. In ICCGHAZ, coarse prior austenite grains were decorated by coarse necklacing martensite-austenite (M-A) constituents. Different layers were observed within M-A constituent, which may be martensite and austenite layers. Charpy absorbed energy of two different HAZ regions (ICCGHAZ containing and non-containing regions) was recorded using instrumental Charpy impact test machine. The results showed that the existence of ICCGHAZ resulted in the sharp drop of Charpy absorbed energy from 180J to 50J, while the existence of only CGHAZ could still lead to good toughness. The fracture surface was 60% brittle in the absence of ICCGHAZ, and 100% brittle in the presence of ICCGHAZ in the impact tested samples. The underlying reason is the microstructure of ICCGHAZ consisted of granular bainite and upper bainite with necklace-type M-A constituent along the grain boundaries. Cleavage fracture initiated from M-A constituent, either through cracking of M-A or debonding from the matrix, was observed at the fracture surface of ICCGHAZ. The presence of necklace type M-A constituent in ICCGHAZ notably increases the susceptibility of cleavage microcrack nucleation. Furthermore, the study of secondary microcracks beneath the CGHAZ and the ICCGHAZ through EBSD suggested that the fracture mechanism changes from nucleation-controlled in the CGHAZ to propagation-controlled in the ICCGHAZ because of the presence of necklace-type M-A constituent in the ICCGHAZ region. Both fracture mechanism contribute to the poor toughness of the sample contained ICCGHAZ. In conclusion, big prior austenite grains with low density of HAB plus coarse necklacing M-A products along grain boundary is the dominant factor resulting in low toughness.

Model of coordination melting of crystals and anisotropy of physical and chemical properties of the surface

NASA Astrophysics Data System (ADS)

Bokarev, Valery P.; Krasnikov, Gennady Ya

2018-02-01

Based on the evaluation of the properties of crystals, such as surface energy and its anisotropy, the surface melting temperature, the anisotropy of the work function of the electron, and the anisotropy of adsorption, were shown the advantages of the model of coordination melting (MCM) in calculating the surface properties of crystals. The model of coordination melting makes it possible to calculate with an acceptable accuracy the specific surface energy of the crystals, the anisotropy of the surface energy, the habit of the natural crystals, the temperature of surface melting of the crystal, the anisotropy of the electron work function and the anisotropy of the adhesive properties of single-crystal surfaces. The advantage of our model is the simplicity of evaluating the surface properties of the crystal based on the data given in the reference literature. In this case, there is no need for a complex mathematical tool, which is used in calculations using quantum chemistry or modeling by molecular dynamics.

Reference analysis of the signal + background model in counting experiments

NASA Astrophysics Data System (ADS)

Casadei, D.

2012-01-01

The model representing two independent Poisson processes, labelled as ``signal'' and ``background'' and both contributing additively to the total number of counted events, is considered from a Bayesian point of view. This is a widely used model for the searches of rare or exotic events in presence of a background source, as for example in the searches performed by high-energy physics experiments. In the assumption of prior knowledge about the background yield, a reference prior is obtained for the signal alone and its properties are studied. Finally, the properties of the full solution, the marginal reference posterior, are illustrated with few examples.

Considerations for effusive cryovolcanism on Europa: The post-Galileo perspective

NASA Astrophysics Data System (ADS)

Fagents, Sarah A.

2003-12-01

Cryovolcanic resurfacing is a popular mechanism to explain relatively young surface units on icy satellites of Jupiter, Saturn, Uranus, and Neptune. Prior to the Galileo data acquired between 1996 and 2001, Europa was thought to have undergone significant cryovolcanic resurfacing, facilitated by a global ocean beneath the icy surface. However, close examination of Galileo data at resolutions much better than those of Voyager images show that many of the features previously thought to be cryovolcanic are commonly best explained by other formative mechanisms, including tectonism and diapirism. In this study, I present an examination of the characteristics of a variety of Europan surface features for which effusive cryovolcanism is a possible origin, including apparently lobate ``flows,'' certain elliptical to circular lenticulae, and low-lying, smooth, low-albedo surfaces. A review of cryovolcanic eruption theory, together with Galileo data analysis of Europan surface geology and composition, indicates that cryovolcanism is a viable, though not unequivocal, explanation for some of these features. Some constraints on cryomagma properties and lithospheric structure are offered for these cases. The presence of small-volume, low-viscosity effusions is supported by observations and modeling. Some positive relief lenticulae could represent more viscous effusions, although diapirism may be a preferable explanation. However, strong evidence is lacking for cryovolcanic resurfacing on a large scale. On the basis of our experience with Galileo images of Europa (and Ganymede), Voyager-era inferences for widespread cryovolcanism on icy satellites may be overstated and will need to be carefully reexamined in the light of new data from upcoming spacecraft missions.

A novel method to scale up fungal endophyte isolations

USDA-ARS?s Scientific Manuscript database

Estimations of species diversity are influenced by sampling intensity which in turn is influenced by methodology. For fungal endophyte diversity studies, the methodology includes surface-sterilization prior to isolation of endophytes. Surface-sterilization is an essential component of fungal endophy...

Automated Telerobotic Inspection Of Surfaces

NASA Technical Reports Server (NTRS)

Balaram, J.; Prasad, K. Venkatesh

1996-01-01

Method of automated telerobotic inspection of surfaces undergoing development. Apparatus implementing method includes video camera that scans over surfaces to be inspected, in manner of mine detector. Images of surfaces compared with reference images to detect flaws. Developed for inspecting external structures of Space Station Freedom for damage from micrometeorites and debris from prior artificial satellites. On Earth, applied to inspection for damage, missing parts, contamination, and/or corrosion on interior surfaces of pipes or exterior surfaces of bridges, towers, aircraft, and ships.

Contributions of feature shapes and surface cues to the recognition of facial expressions.

PubMed

Sormaz, Mladen; Young, Andrew W; Andrews, Timothy J

2016-10-01

Theoretical accounts of face processing often emphasise feature shapes as the primary visual cue to the recognition of facial expressions. However, changes in facial expression also affect the surface properties of the face. In this study, we investigated whether this surface information can also be used in the recognition of facial expression. First, participants identified facial expressions (fear, anger, disgust, sadness, happiness) from images that were manipulated such that they varied mainly in shape or mainly in surface properties. We found that the categorization of facial expression is possible in either type of image, but that different expressions are relatively dependent on surface or shape properties. Next, we investigated the relative contributions of shape and surface information to the categorization of facial expressions. This employed a complementary method that involved combining the surface properties of one expression with the shape properties from a different expression. Our results showed that the categorization of facial expressions in these hybrid images was equally dependent on the surface and shape properties of the image. Together, these findings provide a direct demonstration that both feature shape and surface information make significant contributions to the recognition of facial expressions. Copyright © 2016 Elsevier Ltd. All rights reserved.

The effects of the initial stages of native-oxide formation on the surface properties of GaSb (001)

NASA Astrophysics Data System (ADS)

Bermudez, V. M.

2013-07-01

Atomically clean surfaces of n-type GaSb (001) have been prepared by a combination of ex-situ wet-chemical treatment in HCl and in-situ annealing in a flux of H atoms in ultra-high vacuum (UHV). The surfaces are exposed to "excited" O2 and studied using primarily x-ray photoelectron spectroscopy. Low O2 exposures, up to ˜3 × 103 Langmuirs (L), result in a partial passivation of electrically active defects as shown by a decrease in upward band bending. Adsorption of O2 in this exposure range appears to form mainly Ga+1 sites, with little or no indication of Ga+3, and saturates at an O coverage of ˜0.2-0.3 monolayers. For exposures of ˜104 L or higher, oxidation occurs through insertion into Ga-Sb bonds as indicated by the onset of Ga+3 as well as of Sb+4 and/or Sb+5 together with the appearance of an O 1s feature. Defects resulting from this process cause a reversal of the band-bending change seen for smaller exposures. Data obtained for the composition of a native oxide formed in situ in UHV are compared with those for a "practical" surface produced by processing under ambient conditions. These results suggest an optimum procedure for forming a Ga2O3 layer prior to the growth by atomic layer deposition of an Al2O3 layer.

Effectiveness of Property Tax Relief in Oregon.

ERIC Educational Resources Information Center

Hartman, William T.; Hwang, C. S.

This study examines the effects of the 1979 Oregon Property Tax Relief Plan on 1980-81 school district budget decisions by comparing the available tax relief, the school expenditures, and the tax levies in the state for the years 1975-81. The history of direct and indirect property tax relief in Oregon is sketched for the years prior to 1979; the…

Wet-chemical passivation of atomically flat and structured silicon substrates for solar cell application

NASA Astrophysics Data System (ADS)

Angermann, H.; Rappich, J.; Korte, L.; Sieber, I.; Conrad, E.; Schmidt, M.; Hübener, K.; Polte, J.; Hauschild, J.

2008-04-01

Special sequences of wet-chemical oxidation and etching steps were optimised with respect to the etching behaviour of differently oriented silicon to prepare very smooth silicon interfaces with excellent electronic properties on mono- and poly-crystalline substrates. Surface photovoltage (SPV) and photoluminescence (PL) measurements, atomic force microscopy (AFM) and scanning electron microscopy (SEM) investigations were utilised to develop wet-chemical smoothing procedures for atomically flat and structured surfaces, respectively. Hydrogen-termination as well as passivation by wet-chemical oxides were used to inhibit surface contamination and native oxidation during the technological processing. Compared to conventional pre-treatments, significantly lower micro-roughness and densities of surface states were achieved on mono-crystalline Si(100), on evenly distributed atomic steps, such as on vicinal Si(111), on silicon wafers with randomly distributed upside pyramids, and on poly-crystalline EFG ( Edge-defined Film-fed- Growth) silicon substrates. The recombination loss at a-Si:H/c-Si interfaces prepared on c-Si substrates with randomly distributed upside pyramids was markedly reduced by an optimised wet-chemical smoothing procedure, as determined by PL measurements. For amorphous-crystalline hetero-junction solar cells (ZnO/a-Si:H(n)/c-Si(p)/Al) with textured c-Si substrates the smoothening procedure results in a significant increase of short circuit current Isc, fill factor and efficiency η. The scatter in the cell parameters for measurements on different cells is much narrower, as compared to conventional pre-treatments, indicating more well-defined and reproducible surface conditions prior to a-Si:H emitter deposition and/or a higher stability of the c-Si surface against variations in the a-Si:H deposition conditions.

Effect on the partial least-squares prediction of yarn properties combining raman and infrared measurements and applying wavelength selection.

PubMed

de Groot, P J; Swierenga, H; Postma, G J; Melssen, W J; Buydens, L M C

2003-06-01

The combination of Raman and infrared spectroscopy on the one hand and wavelength selection on the other hand is used to improve the partial least-squares (PLS) prediction of seven selected yarn properties. These properties are important for on-line quality control during production. From 71 yarn samples, the Raman and infrared spectra are measured and reference methods are used to determine the selected properties. Making separate PLS models for all yarn properties using the Raman and infrared spectra, prior to wavelength selection, reveals that Raman spectroscopy outperforms infrared spectroscopy. If wavelength selection is applied, the PLS prediction error decreases and the correlation coefficient increases for all properties. However, a substantial wavelength selection effect is present for the infrared spectra compared to the Raman spectra. For the infrared spectra, wavelength selection results in PLS prediction errors comparable with the prediction performance of the Raman spectra prior to wavelength selection. Concatenating the Raman and infrared spectra does not enhance the PLS prediction performance, not even after wavelength selection. It is concluded that an infrared spectrometer, combined with a wavelength selection procedure, can be used if no (suitable) Raman instrument is available.

32 CFR 644.166 - Authority and applicability.

Code of Federal Regulations, 2011 CFR

2011-07-01

....166 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY (CONTINUED) REAL PROPERTY REAL ESTATE HANDBOOK Acquisition Procurement of Options Prior to Real Estate Directives (military... parcel of real property before or after its acquisition is authorized by law, if he considers it suitable...

Ecological controls on N2O emission in surface litter and near-surface soil of a managed grassland: modelling and measurements

NASA Astrophysics Data System (ADS)

Grant, Robert F.; Neftel, Albrecht; Calanca, Pierluigi

2016-06-01

Large variability in N2O emissions from managed grasslands may occur because most emissions originate in surface litter or near-surface soil where variability in soil water content (θ) and temperature (Ts) is greatest. To determine whether temporal variability in θ and Ts of surface litter and near-surface soil could explain this in N2O emissions, a simulation experiment was conducted with ecosys, a comprehensive mathematical model of terrestrial ecosystems in which processes governing N2O emissions were represented at high temporal and spatial resolution. Model performance was verified by comparing N2O emissions, CO2 and energy exchange, and θ and Ts modelled by ecosys with those measured by automated chambers, eddy covariance (EC) and soil sensors on an hourly timescale during several emission events from 2004 to 2009 in an intensively managed pasture at Oensingen, Switzerland. Both modelled and measured events were induced by precipitation following harvesting and subsequent fertilizing or manuring. These events were brief (2-5 days) with maximum N2O effluxes that varied from < 1 mgNm-2h-1 in early spring and autumn to > 3 mgNm-2h-1 in summer. Only very small emissions were modelled or measured outside these events. In the model, emissions were generated almost entirely in surface litter or near-surface (0-2 cm) soil, at rates driven by N availability with fertilization vs. N uptake with grassland regrowth and by O2 supply controlled by litter and soil wetting relative to O2 demand from microbial respiration. In the model, NOx availability relative to O2 limitation governed both the reduction of more oxidized electron acceptors to N2O and the reduction of N2O to N2, so that the magnitude of N2O emissions was not simply related to surface and near-surface θ and Ts. Modelled N2O emissions were found to be sensitive to defoliation intensity and timing which controlled plant N uptake and soil θ and Ts prior to and during emission events. Reducing leaf area index (LAI) remaining after defoliation to half that under current practice and delaying harvesting by 5 days raised modelled N2O emissions by as much as 80 % during subsequent events and by an average of 43 % annually. Modelled N2O emissions were also found to be sensitive to surface soil properties. Increasing near-surface bulk density by 10 % raised N2O emissions by as much as 100 % during emission events and by an average of 23 % annually. Relatively small spatial variation in management practices and soil surface properties could therefore cause the large spatial variation in N2O emissions commonly found in field studies. The global warming potential from annual N2O emissions in this intensively managed grassland largely offset those from net C uptake in both modelled and field experiments. However, model results indicated that this offset could be adversely affected by suboptimal land management and soil properties.

Relationship between surface property and catalytic application of amorphous NiP/Hβ catalyst for n-hexane isomerization

NASA Astrophysics Data System (ADS)

Chen, Jinshe; Duan, Zunbin; Song, Zhaoyang; Zhu, Lijun; Zhou, Yulu; Xiang, Yuzhi; Xia, Daohong

2017-12-01

The amorphous NiP nanoparticles were synthesized and a novel amorphous NiP/Hβ catalyst was prepared successfully further. Due to the superior surface property of amorphous NiP/Hβ catalyst, it exhibited good catalytic application for n-hexane isomerization. The catalytic activity of amorphous NiP/Hβ catalyst was close to that of the prepared Pt/Hβ sample, and better than that of commercial catalyst and crystalline Ni2P/Hβ catalyst. What's more, the amorphous NiP/Hβ catalyst shows high resistance to different sulfur compounds and water on account of its unique surface property. The effect of loading amounts on surface property and catalytic performance was investigated, and the structure-function relationship among them was studied ulteriorly. The results demonstrate that loading amounts have effect on textural property and surface acid property, which further affect the catalytic performance. The 10 wt.% NiP/Hβ sample has appropriate pore structure and acid property with uniformly dispersed NiP nanoparticles on surface, which is helpful for providing suitable synergistic effect. The effects of reaction conditions on surface reactions and the mechanism for n-hexane isomerization were investigated further. Based on these results, the amorphous NiP/Hβ catalyst with superior surface property probably pavesa way to overcome the drawbacks of traditional noble metal catalyst, which shows good catalytic application prospects.

26 CFR 1.1014-6 - Special rule for adjustments to basis where property is acquired from a decedent prior to his death.

Code of Federal Regulations, 2012 CFR

2012-04-01

... to himself and W, his wife, as tenants by the entirety. Under local law each spouse was entitled to... the property was $40,000. The entire value of the property was included in H's gross estate. H and W...,500 depreciation will be allocated to W. The adjusted basis of the property in W's hands of January 1...

26 CFR 1.1014-6 - Special rule for adjustments to basis where property is acquired from a decedent prior to his death.

Code of Federal Regulations, 2013 CFR

2013-04-01

... to himself and W, his wife, as tenants by the entirety. Under local law each spouse was entitled to... the property was $40,000. The entire value of the property was included in H's gross estate. H and W...,500 depreciation will be allocated to W. The adjusted basis of the property in W's hands of January 1...

[Stimuli sensitive changes in electrical surface properties of soft membranes: from a synthesized polymer to a biological system].

PubMed

Makino, K

1997-01-01

The electrical surface properties of biological cells have been studied, which provided us with the fundamental knowledge about the cell surface. The change in shape or biological functions of cells may affect the surface properties and can be detected by electrokinetic measurements. Biological cell surfaces are covered with polysaccharide chains, some are charged and some are not. Some polysaccharides produce a hydrogel matrixes under a proper condition. We thus consider it reasonable that cell surface is approximated by a hydrogel surface. Electrophoretic mobility measurements are useful for studying the surface properties of biological cells suspended as colloidal particles in an electrolyte solution. The electro-osmotic velocity measurements on the other hand are advantageous to the study of the surface properties of slab-shaped biological systems such as membranes. This work was started with a hydrogel, as a model material. As a hydrogel, poly(N-isopropylacrylamide) poly(NIPAAm), abbreviated as hereafter, was chosen, because this hydrogel changes its volume depending on temperature. The dependence of the electrophoretic mobility of latex particles covered with poly(NIPAAm) hydrogel layer or of the electro-osmotic mobility on poly(NIPAAm) plate upon temperature and ionic strength of the dispersing medium was well explained with an electrophoretic mobility formula for "soft particles" developed by Ohshima. The electrokinetic measurements and the explanation of data with an electrophoretic mobility formula for "soft particles" give us information about the surface charge density and the "softness" of soft surfaces. On the basis of the findings with hydrogels, we have discussed the relationship between the changes in shape or function of the biological cells and the change in physicochemical surface properties using these measurements. To study the change in physicochemical properties of the cell surface caused by apoptosis, we have measured the electrophoretic mobilities of intact and apoptotic human promyelocytic leukemia cell lines, HL-60RG cells. We have also studied the differences observed in surface properties of malignant lymphosarcoma cell line, RAW117-P, and its variant, RAW117-H10, with a high metastatic property to the liver. In both cases, the cell surfaces became softer by the changes of biological functions. We have applied electrophoresis and electro-osmosis measurements to the study of the electrokinetic surface properties of rat basophilic leukemia cells, RBL cells. It was also found that the surface of Human umbilical vein endothelial cells, HUVEC, is considerably soft as compared with those of other biological cells we have studied before.

Bayesian predictive power: choice of prior and some recommendations for its use as probability of success in drug development.

PubMed

Rufibach, Kaspar; Burger, Hans Ulrich; Abt, Markus

2016-09-01

Bayesian predictive power, the expectation of the power function with respect to a prior distribution for the true underlying effect size, is routinely used in drug development to quantify the probability of success of a clinical trial. Choosing the prior is crucial for the properties and interpretability of Bayesian predictive power. We review recommendations on the choice of prior for Bayesian predictive power and explore its features as a function of the prior. The density of power values induced by a given prior is derived analytically and its shape characterized. We find that for a typical clinical trial scenario, this density has a u-shape very similar, but not equal, to a β-distribution. Alternative priors are discussed, and practical recommendations to assess the sensitivity of Bayesian predictive power to its input parameters are provided. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Low temperature self-cleaning properties of superhydrophobic surfaces

NASA Astrophysics Data System (ADS)

Wang, Fajun; Shen, Taohua; Li, Changquan; Li, Wen; Yan, Guilong

2014-10-01

Outdoor surfaces are usually dirty surfaces. Ice accretion on outdoor surfaces could lead to serious accidents. In the present work, the superhydrophobic surface based on 1H, 1H, 2H, 2H-Perfluorodecanethiol (PFDT) modified Ag/PDMS composite was prepared to investigate the anti-icing property and self-cleaning property at temperatures below freezing point. The superhydrophobic surface was deliberately polluted with activated carbon before testing. It was observed that water droplet picked up dusts on the cold superhydrophobic surface and took it away without freezing at a measuring temperature of -10 °C. While on a smooth PFDT surface and a rough surface base on Ag/PDMS composite without PFDT modification, water droplets accumulated and then froze quickly at the same temperature. However, at even lower temperature of -12 °C, the superhydrophobic surface could not prevent the surface water from icing. In addition, it was observed that the frost layer condensed from the moisture pay an important role in determining the low temperature self-cleaning properties of a superhydrophobic surface.

Some fundamental properties and reactions of ice surfaces at low temperatures.

PubMed

Park, Seong-Chan; Moon, Eui-Seong; Kang, Heon

2010-10-14

Ice surfaces offer a unique chemical environment in which reactions occur quite differently from those in liquid water or gas phases. In this article, we examine the basic properties of ice surfaces below the surface premelting temperature and discuss some of the recent investigations carried out on reactions at the ice surfaces. The static and dynamic properties of an ice surface as a reaction medium, such as its structure, molecule diffusion and proton transfer dynamics, and the surface preference of hydronium and hydroxide ions, are discussed in relation to the reactivity of the surface.

Effect of processing history on the surface interfacial properties of budesonide in carrier-based dry-powder inhalers.

PubMed

Shur, Jagdeep; Pitchayajittipong, Chonladda; Rogueda, Philippe; Price, Robert

2013-08-01

Influence of air-jet micronization, post-micronization conditioning and storage on the surface properties of budesonide in dry-powder inhaler formulations was investigated. Crystalline budesonide was air jet-micronized and conditioned using organic vapor. Particle engineering was also used to fabricate respirable particles of budesonide. Surface imaging by atomic force microscopy suggested that micronized material possessed process-induced surface disorder, which relaxed upon conditioning with organic vapor. Particle engineered material was devoid of such surface disorder. Surface interfacial properties of all batches were different and correlated to in vitro fine particle delivery. The surface properties and in vitro performance of the conditioned material changed upon storage of the budesonide at 44% relative humidity and 25°C, while the micronized and particle-engineered material remained stable. These data suggest that processing conditions of budesonide affected the surface properties of the material, which was demonstrated to have direct affect on dry-powder inhaler formulation performance.

Interdigitation between Triglycerides and Lipids Modulates Surface Properties of Lipid Droplets.

PubMed

Bacle, Amélie; Gautier, Romain; Jackson, Catherine L; Fuchs, Patrick F J; Vanni, Stefano

2017-04-11

Intracellular lipid droplets (LDs) are the main cellular site of metabolic energy storage. Their structure is unique inside the cell, with a core of esterified fatty acids and sterols, mainly triglycerides and sterol esters, surrounded by a single monolayer of phospholipids. Numerous peripheral proteins, including several that were previously associated with intracellular compartments surrounded by a lipid bilayer, have been recently shown to target the surface of LDs, but how they are able to selectively target this organelle remains largely unknown. Here, we use atomistic and coarse-grained molecular dynamics simulations to investigate the molecular properties of the LD surface and to characterize how it differs from that of a lipid bilayer. Our data suggest that although several surface properties are remarkably similar between the two structures, key differences originate from the interdigitation between surface phospholipids and core neutral lipids that occurs in LDs. This property is extremely sensitive to membrane undulations, unlike in lipid bilayers, and it strongly affects both lipid-packing defects and the lateral pressure profile. We observed a marked change in overall surface properties for surface tensions >10 mN/m, indicative of a bimodal behavior. Our simulations provide a comprehensive molecular characterization of the unique surface properties of LDs and suggest how the molecular properties of the surface lipid monolayer can be modulated by the underlying neutral lipids. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Jet blown PTFE for control of biocompatibility

NASA Astrophysics Data System (ADS)

Leibner, Evan Scott

The development of fully hemocompatible cardiovascular biomaterials will have a major impact on the practice of modern medicine. Current artificial surfaces, unlike native vascular surfaces, are not able to control clot and thrombus formation. Protein interactions are an important component in hemocompatibility and can result in decreased patency due to thrombus formation or surface passivation which can improve endothelization. It is believed that controlling these properties, specifically the nanometer sizes of the fibers on the material's surface, will allow for better control of biological responses. The biocompatibility of Teflon, a widely used polymer for vascular grafts, would be improved with nanostructured control of surface features. Due to the difficultly in processing polytetrafluoroethylene (PTFE), it has not been possible to create nanofibrous PTFE surfaces. The novel technique of Jet Blowing allows for the formation of nanostructured PTFE (nPTFE). A systematic investigation into controlling polymer properties by varying the processing conditions of temperature, pressure, and gas used in the Jet Blowing allows for an increased understanding of the effects of plasticization on the material's properties. This fundamental understanding of the material science behind the Jet Blowing process has enabled control of the micro and nanoscale structure of nPTFE. While protein adsorption, a key component of biocompatibility, has been widely studied, it is not fully understood. Major problems in the field of biomaterials include a lack of standard protocols to measure biocompatibility, and inconstant literature on protein adsorption. A reproducible protocol for measuring protein adsorption onto superhydrophobic surfaces (ePTFE and nPTFE) has been developed. Both degassing of PBS buffer solutions and evacuation of the air around the expanded PTFE (ePTFE) prior to contact with protein solutions are essential. Protein adsorption experiments show a four-fold difference in the measure of proteins adsorbed using radiometry (I-125 labeled human serum albumin (HSA)) and electrophoresis (unlabeled HSA). This provides evidence that the standard method of radiolabeled protein for measuring adsorption does not fully account for changes to the HSA molecules due to labeling. The differences between measured protein values can be attributed to the radiolabel affecting the HSA hydrophobicity resulting in a change in the protein's interactions with the hydrophobic surface. Additionally, our work has provided repeatable results showing that the amount of protein adsorbed onto the polymer surface, after washing, accounted for only 65% of the amount of protein that was removed from solution based on depletion analysis. This implies that measurement of the amount of strongly bound protein on the material significantly underestimates the actual amount of protein adsorbing into the surface region of the material interface. HSA adsorption isotherms demonstrate an increase in protein adsorption capacity on the nPTFE surface compared to adsorption on the same surface area of ePTFE. Preliminary cell work shows that the nPTFE surfaces had a larger number of cells growing on the surface of the material when compared to ePTFE surfaces. The research also shows that while most endothelial cells were not viable on the ePTFE surface after 96 hours, they remained alive on the nPTFE surface during that same time period. Surface functionalization using ammonia plasma has been performed. X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of amine groups on the nPTFE surface. The amine groups can be used to couple polypeptides onto the PTFE surface in the future. The selection of different peptides will allow for selective control of cell adhesion. This research shows that nPTFE has potential for improved biocompatibility over standard ePTFE, based on increased protein adsorption capacity, increased viability of endothelial cells, and the ability to plasma modify the PTFE surface.

Abrasion resistant composition

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

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

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 themore » metal matrix.« less

Exploiting the flexibility and the polarization of ferroelectric perovskite surfaces to achieve efficient photochemistry and enantiospecificity

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

Rappe, Andrew

This research project explored the catalytic properties of complex surfaces of functional materials. The PI used first-principles density functional theory (DFT) calculations to explore a tightly integrated set of properties. The physical properties of complex functional materials that influence surface chemistry were explored, including bulk and surface electric dipoles, and surface conductivity. The energetic, compositional, electronic, and chemical properties of the surfaces of these materials were explored in detail, and connections between material properties and chemical reactivity were established. This project led to 28 publications, including Nat. Comm., JACS, 3 PRL, 7 PRB, 2 ACS Nano, 2 Nano Lett., 4more » JPCL, 2 JCP, Chem. Mater., ACS Appl. Mater. Interfaces, Phys. Rev. Appl., and a U.S. Patent on surface catalysts. The key accomplishments in this project involved work in six coordinated areas: pioneering ways to control bulk dipoles in order to dynamically affect catalysis, exploring novel ways of bringing charge to the surface for redox catalysis, nonstoichiometric surfaces offering new sites for heterogeneous catalysis, illustrating how surface catalysis responds to applied pressure, catalytic growth of carbon-based materials, and new computational methods allowing more accurate exploration of molecule-surface interactions« less

Structural and electronic properties of low-index stoichiometric Cu2ZnSnS4 surfaces

NASA Astrophysics Data System (ADS)

Jia, Zhan-Ju; Wang, Yu-An; Zhao, Zong-Yan; Liu, Qing-Ju

2018-05-01

Over the past few years, quaternary Cu2ZnSnS4 (CZTS) has attracted a great deal of attention as the most promising photovoltaic absorber layer, due to its abundance and non-toxic properties. However, the significant surface structures and properties for photo-catalytic absorption layers have not yet been studied in detail for CZTS. Hence, the surface structure and electronic properties of low-index stoichiometric CZTS surfaces are calculated based on density functional theory. The relaxation is much large for the (001), (100), (101) and (112) surfaces. Moreover, more surface states appear at the bottom of conduction band and the top of valence band. The conduction band is mainly composed of S-3p and Sn-5p orbits. The valence band top is mainly composed of S-3p and Cu-3d orbits. The band gap values of five surfaces do not vary greatly. The dangling bond density for the (112) surfaces is minimal, resulting in minimum surface energy. Finally, the equilibrium morphology of CZTS is constructed by the Wulff rule. It is found that the {101} surface is the dominant surface (72.6%). These results will help us to better understand the surface properties of absorption layer that is related to CZTS surface and provide theoretical support for future experimental studies.

26 CFR 20.2056A-7 - Allowance of prior transfer credit under section 2013.

Code of Federal Regulations, 2010 CFR

2010-04-01

... section 2013. 20.2056A-7 Section 20.2056A-7 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE... Taxable Estate § 20.2056A-7 Allowance of prior transfer credit under section 2013. (a) Property subject to QDOT election. Section 2056(d)(3) provides special rules for computing the section 2013 credit allowed...

Tailoring surface properties of ArF resists thin films with functionally graded materials (FGM)

NASA Astrophysics Data System (ADS)

Takemoto, Ichiki; Ando, Nobuo; Edamatsu, Kunishige; Fuji, Yusuke; Kuwana, Koji; Hashimoto, Kazuhiko; Funase, Junji; Yokoyama, Hiroyuki

2007-03-01

Our recent research effort has been focused on new top coating-free 193nm immersion resists with regard to leaching of the resist components and lithographic performance. We have examined methacrylate-based resins that control the surface properties of ArF resists thin films by surface segregation behavior. For a better understanding of the surface properties of thin films, we prepared the six resins (Resin 1-6) that have three types fluorine containing monomers, a new monomer (Monomer A), Monomer B and Monomer C, respectively. We blended the base polymer (Resin 0) with Resin (1-6), respectively. We evaluated contact angles, surface properties and lithographic performances of the polymer blend resists. The static and receding contact angles of the resist that contains Resin (1-6) are greater than that of the base polymer (Resin 0) resist. The chemical composition of the surface of blend polymers was investigated with X-ray photoelectron spectroscopy (XPS). It was shown that there was significant segregation of the fluorine containing resins to the surface of the blend films. We analyzed Quantitative Structure-Property Relationships (QSPR) between the surface properties and the chemical composition of the surface of polymer blend resists. The addition of 10 wt% of the polymer (Resin 1-6) to the base polymer (Resin 0) did not influence the lithographic performance. Consequently, the surface properties of resist thin films can be tailored by the appropriate choice of fluorine containing polymer blends.

Contributions of feature shapes and surface cues to the recognition and neural representation of facial identity.

PubMed

Andrews, Timothy J; Baseler, Heidi; Jenkins, Rob; Burton, A Mike; Young, Andrew W

2016-10-01

A full understanding of face recognition will involve identifying the visual information that is used to discriminate different identities and how this is represented in the brain. The aim of this study was to explore the importance of shape and surface properties in the recognition and neural representation of familiar faces. We used image morphing techniques to generate hybrid faces that mixed shape properties (more specifically, second order spatial configural information as defined by feature positions in the 2D-image) from one identity and surface properties from a different identity. Behavioural responses showed that recognition and matching of these hybrid faces was primarily based on their surface properties. These behavioural findings contrasted with neural responses recorded using a block design fMRI adaptation paradigm to test the sensitivity of Haxby et al.'s (2000) core face-selective regions in the human brain to the shape or surface properties of the face. The fusiform face area (FFA) and occipital face area (OFA) showed a lower response (adaptation) to repeated images of the same face (same shape, same surface) compared to different faces (different shapes, different surfaces). From the behavioural data indicating the critical contribution of surface properties to the recognition of identity, we predicted that brain regions responsible for familiar face recognition should continue to adapt to faces that vary in shape but not surface properties, but show a release from adaptation to faces that vary in surface properties but not shape. However, we found that the FFA and OFA showed an equivalent release from adaptation to changes in both shape and surface properties. The dissociation between the neural and perceptual responses suggests that, although they may play a role in the process, these core face regions are not solely responsible for the recognition of facial identity. Copyright © 2016 Elsevier Ltd. All rights reserved.

24 CFR 570.513 - Lump sum drawdown for financing of property rehabilitation activities.

Code of Federal Regulations, 2011 CFR

2011-04-01

... agreement to undertake activities, based on either: (i) Prior level of rehabilitation activity; or (ii... property rehabilitation activities. 570.513 Section 570.513 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR COMMUNITY PLANNING...

28 CFR 8.6 - Quick-release authority.

Code of Federal Regulations, 2010 CFR

2010-07-01

...-release authority. Where the forfeiture proceedings are administrative, the Special Agent in Charge, prior to forfeiture, is authorized to release property seized for forfeiture. The property can be quick... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Quick-release authority. 8.6 Section 8.6...

26 CFR 1.341-5 - Application of section.

Code of Federal Regulations, 2010 CFR

2010-04-01

... business activities of the corporation which manufactured, constructed, produced, or purchased the property if such corporation has a substantial prior business history involving the use of such property and continues in business, or (ii) For the purpose of an orderly liquidation of the business if the corporation...

Surface properties of beached plastics.

PubMed

Fotopoulou, Kalliopi N; Karapanagioti, Hrissi K

2015-07-01

Studying plastic characteristics in the marine environment is important to better understand interaction between plastics and the environment. In the present study, high-density polyethylene (HDPE), polyethylene terephalate (PET), and polyvinyl chloride (PVC) samples were collected from the coastal environment in order to study their surface properties. Surface properties such as surface functional groups, surface topography, point of zero charge, and color change are important factors that change during degradation. Eroded HDPE demonstrated an altered surface topography and color and new functional groups. Eroded PET surface was uneven, yellow, and occasionally, colonized by microbes. A decrease in Fourier transform infrared (FTIR) peaks was observed for eroded PET suggesting that degradation had occurred. For eroded PVC, its surface became more lamellar and a new FTIR peak was observed. These surface properties were obtained due to degradation and could be used to explain the interaction between plastics, microbes, and pollutants.

Theoretical study on the electronic and optical properties of bulk and surface (001) InxGa1-xAs

NASA Astrophysics Data System (ADS)

Liu, XueFei; Ding, Zhao; Luo, ZiJiang; Zhou, Xun; Wei, JieMin; Wang, Yi; Guo, Xiang; Lang, QiZhi

2018-05-01

The optical properties of surface and bulk InxGa1-xAs materials are compared systematically first time in this paper. The band structures, density of states and optical properties including dielectric function, reflectivity, absorption coefficient, loss function and refractive index of bulk and surface InxGa1-xAs materials are investigated by first-principles based on plane-wave pseudo-potentials method within the LDA approximation. The results agree well with the available theoretical and experimental studies and indicate that the electronic and optical properties of bulk and surface InxGa1-xAs materials are much different, and the results show that the considered optical properties of the both materials vary with increasing indium composition in an opposite way. The calculations show that the optical properties of surface In0.75Ga0.25As material are unexpected to be far from the other two indium compositions of surface InxGa1-xAs materials while the optical properties of bulk InxGa1-xAs materials vary with increasing indium composition in an expected regular way.

Adsorption properties of subtropical and tropical variable charge soils: Implications from climate change and biochar amendment

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

Xu, Ren-Kou; Qafoku, Nikolla; Van Ranst, Eric

2016-01-25

This review paper attempts to summarize the progress made in research efforts conducted over the last years to study the surface chemical properties of the tropical and subtropical soils, usually called variable charge soils, and the way they response to different management practices. The paper is composed of an introductory section that provides a brief discussion on the surface chemical properties of these soils, and five other review sections. The focus of these sections is on the evolution of surface chemical properties during the development of the variable charge properties (second section), interactions between oppositely charged particles and the resultingmore » effects on the soil properties and especially on soil acidity (third section), the surface effects of low molecular weight organic acids sorbed to mineral surfaces and the chemical behavior of aluminum (fourth section), and the crop straw derived biochar induced changes of the surface chemical properties of these soils (fifth section). A discussion on the effect of climate change variables on the properties of the variable charge soils is included at the end of this review paper (sixth section).« less

Probing the defects in nano-semiconductors using positrons

NASA Astrophysics Data System (ADS)

Nambissan, P. M. G.

2011-01-01

Positron annihilation spectroscopy (PAS) is a very useful tool to study the defect properties of nanoscale materials. The ability of thermalized positrons to diffuse over to the surfaces of nanocrystallites prior to annihilation helps to explore the disordered atomic arrangement over there and is very useful in understanding the structure and properties of nanomaterials. As examples, the results of studies on FeS2 nanorods and ZnS nanoparticles are presented. In semiconductor nanoparticles, there are positron trapping sites within the grains also and these are characterised by using appropriate models on the measured positron lifetimes. We have observed vivid changes in the measured positron lifetimes and Doppler broadened gamma ray spectral lineshapes during structural transformations prompted by substitutional effects in Mn2+-doped ZnS nanorods. Interestingly, the nanoparticles did not exhibit the transformation, implying the morphologies of the nanosystems playing a decisive role. Quantum confinement effect in CdS nanoparticles was another phenomenon that could be seen through positron annihilation experiments. Coincidence Doppler broadening measurements have been useful to identify the elemental environment around the vacancy clusters that trap positrons. Recent studies on nanocrystalline oxide and sulphide semiconductors are also discussed.

Relating the temporal change observed by AIRSAR to surface and canopy properties of mixed conifer and hardwood forests of northern Michigan

NASA Technical Reports Server (NTRS)

Dobson, M. Craig; Mcdonald, Kyle; Ulaby, Fawwaz T.; Sharik, Terry

1991-01-01

The mixed hardwood and conifer forests of northern Michigan were overflown by a 3-frequency airborne imaging radar in Apr. and Jul. 1990. A set of 10 x 10 km test sites near the University of Michigan Biological Station at Douglas Lake and within the Hiawatha National Forest in the upper peninsula of Michigan contained training stands representing the various forest species typical of forest communities across the ecotone between the coniferous boreal forest and mid-latitude hardwood and coniferous forests. The polarimetric radar data were externally calibrated to allow interdate comparisons. The Apr. flight was prior to bud-break of deciduous species and patchy snowcover was present. The Jul. flights occurred during and 2 days after heavy rain showers, and provide a unique opportunity to examine the differences in radar backscatter attributable to intercepted precipitation. Analyses show that there are significant changes in backscattering between biophysically dissimilar forest stands on any given date and also between dates for a given forest stand. These differences in backscattering can be related to moisture properties of the forest floor and the overlying canopy and also to the quantity and organizational structure of the above-ground biomass.

Cicada Wing Surface Topography: An Investigation into the Bactericidal Properties of Nanostructural Features.

PubMed

Kelleher, S M; Habimana, O; Lawler, J; O' Reilly, B; Daniels, S; Casey, E; Cowley, A

2016-06-22

Recently, the surface of the wings of the Psaltoda claripennis cicada species has been shown to possess bactericidal properties and it has been suggested that the nanostructure present on the wings was responsible for the bacterial death. We have studied the surface-based nanostructure and bactericidal activity of the wings of three different cicadas (Megapomponia intermedia, Ayuthia spectabile and Cryptotympana aguila) in order to correlate the relationship between the observed surface topographical features and their bactericidal properties. Atomic force microscopy and scanning electron microscopy performed in this study revealed that the tested wing species contained a highly uniform, nanopillar structure on the surface. The bactericidal properties of the cicada wings were investigated by assessing the viability of autofluorescent Pseudomonas fluorescens cells following static adhesion assays and targeted dead/live fluorescence staining through direct microscopic counting methods. These experiments revealed a 20-25% bacterial surface coverage on all tested wing species; however, significant bactericidal properties were observed in the M. intermedia and C. aguila species as revealed by the high dead:live cell ratio on their surfaces. The combined results suggest a strong correlation between the bactericidal properties of the wings and the scale of the nanotopography present on the different wing surfaces.

Modification of the structural and magnetic properties of granular FePt films by seed layer conditioning

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

Wicht, S., E-mail: s.wicht@ifw-dresden.de; TU Dresden, Institut für Werkstoffwissenschaft, Helmholtzstraße 10, D-01069 Dresden; Neu, V.

2015-01-07

The steadily increasing amount of digital information necessitates the availability of reliable high capacity magnetic data storage. Here, future hard disk drives with extended areal storage densities beyond 1.0 Tb/in{sup 2} are envisioned by using high anisotropy granular and chemically L1{sub 0}-ordered FePt (002) perpendicular media within a heat-assisted magnetic recording scheme. Perpendicular texturing of the [001] easy axes of the individual grains can be achieved by using MgO seed layers. It is therefore investigated, if and how an Ar{sup +} ion irradiation of the MgO seed layer prior to the deposition of the magnetic material influences the MgO surfacemore » properties and hereby the FePt [001] texture. Structural investigations reveal a flattening of the seed layer surface accompanied by a change in the morphology of the FePt grains. Moreover, the fraction of small second layer particles and the degree of coalescence of the primarily deposited FePt grains strongly increases. As for the magnetic performance, this results in a reduced coercivity along the magnetic easy axis (out of plane) and in enhanced hard axis (in-plane) remanence values. The irradiation induced changes in the magnetic properties of the granular FePt-C films are traced back to the accordingly modified atomic structure of the FePt-MgO interface region.« less

Microstructure and Antiwear Property of Laser Cladding Ni-Co Duplex Coating on Copper.

PubMed

Wang, Yiyong; Liang, Zhipeng; Zhang, Junwei; Ning, Zhe; Jin, Hui

2016-07-28

Ni-Co duplex coatings were cladded onto Cu to improve the antiwear properties of Cu products. Prior to laser cladding, n-Al₂O₃/Ni layers were introduced as interlayers between laser cladding coatings and Cu substrates to improve the laser absorptivity of these substrates and ensure defect-free laser cladding coatings. The structure and morphology of the coatings were characterized by scanning electron microscopy and optical microscopy, and the phases of the coatings were analyzed by X-ray diffraction. Their hardness was measured using a microhardness tester. Experimental results showed that defect-free composite coatings were obtained and that the coatings were metallurgically bonded to the substrates. The surface of the Ni-Co duplex coatings comprised a Co-based solid solution, Cr₇C₃, (Fe,Ni) 23 C₆, and other strengthening phases. The microhardness and wear resistance of the duplex coatings were significantly improved compared with the Cu substrates. The average microhardness of the cladded coatings was 845.6 HV, which was approximately 8.2 times greater than that of the Cu substrates (102.6 HV). The volume loss of the Cu substrates was approximately 7.5 times greater than that of the Ni-Co duplex coatings after 60 min of sliding wear testing. The high hardness of and lack of defects in the Ni-Co duplex coatings reduced the plastic deformation and adhesive wear of the Cu substrates, resulting in improved wear properties.

Estimating spatially distributed turbulent heat fluxes from high-resolution thermal imagery acquired with a UAV system

PubMed Central

Brenner, Claire; Thiem, Christina Elisabeth; Wizemann, Hans-Dieter; Bernhardt, Matthias; Schulz, Karsten

2017-01-01

ABSTRACT In this study, high-resolution thermal imagery acquired with a small unmanned aerial vehicle (UAV) is used to map evapotranspiration (ET) at a grassland site in Luxembourg. The land surface temperature (LST) information from the thermal imagery is the key input to a one-source and two-source energy balance model. While the one-source model treats the surface as a single uniform layer, the two-source model partitions the surface temperature and fluxes into soil and vegetation components. It thus explicitly accounts for the different contributions of both components to surface temperature as well as turbulent flux exchange with the atmosphere. Contrary to the two-source model, the one-source model requires an empirical adjustment parameter in order to account for the effect of the two components. Turbulent heat flux estimates of both modelling approaches are compared to eddy covariance (EC) measurements using the high-resolution input imagery UAVs provide. In this comparison, the effect of different methods for energy balance closure of the EC data on the agreement between modelled and measured fluxes is also analysed. Additionally, the sensitivity of the one-source model to the derivation of the empirical adjustment parameter is tested. Due to the very dry and hot conditions during the experiment, pronounced thermal patterns developed over the grassland site. These patterns result in spatially variable turbulent heat fluxes. The model comparison indicates that both models are able to derive ET estimates that compare well with EC measurements under these conditions. However, the two-source model, with a more complex treatment of the energy and surface temperature partitioning between the soil and vegetation, outperformed the simpler one-source model in estimating sensible and latent heat fluxes. This is consistent with findings from prior studies. For the one-source model, a time-variant expression of the adjustment parameter (to account for the difference between aerodynamic and radiometric temperature) that depends on the surface-to-air temperature gradient yielded the best agreement with EC measurements. This study showed that the applied UAV system equipped with a dual-camera set-up allows for the acquisition of thermal imagery with high spatial and temporal resolution that illustrates the small-scale heterogeneity of thermal surface properties. The UAV-based thermal imagery therefore provides the means for analysing patterns of LST and other surface properties with a high level of detail that cannot be obtained by traditional remote sensing methods. PMID:28515537

Estimating spatially distributed turbulent heat fluxes from high-resolution thermal imagery acquired with a UAV system.

PubMed

Brenner, Claire; Thiem, Christina Elisabeth; Wizemann, Hans-Dieter; Bernhardt, Matthias; Schulz, Karsten

2017-05-19

In this study, high-resolution thermal imagery acquired with a small unmanned aerial vehicle (UAV) is used to map evapotranspiration (ET) at a grassland site in Luxembourg. The land surface temperature (LST) information from the thermal imagery is the key input to a one-source and two-source energy balance model. While the one-source model treats the surface as a single uniform layer, the two-source model partitions the surface temperature and fluxes into soil and vegetation components. It thus explicitly accounts for the different contributions of both components to surface temperature as well as turbulent flux exchange with the atmosphere. Contrary to the two-source model, the one-source model requires an empirical adjustment parameter in order to account for the effect of the two components. Turbulent heat flux estimates of both modelling approaches are compared to eddy covariance (EC) measurements using the high-resolution input imagery UAVs provide. In this comparison, the effect of different methods for energy balance closure of the EC data on the agreement between modelled and measured fluxes is also analysed. Additionally, the sensitivity of the one-source model to the derivation of the empirical adjustment parameter is tested. Due to the very dry and hot conditions during the experiment, pronounced thermal patterns developed over the grassland site. These patterns result in spatially variable turbulent heat fluxes. The model comparison indicates that both models are able to derive ET estimates that compare well with EC measurements under these conditions. However, the two-source model, with a more complex treatment of the energy and surface temperature partitioning between the soil and vegetation, outperformed the simpler one-source model in estimating sensible and latent heat fluxes. This is consistent with findings from prior studies. For the one-source model, a time-variant expression of the adjustment parameter (to account for the difference between aerodynamic and radiometric temperature) that depends on the surface-to-air temperature gradient yielded the best agreement with EC measurements. This study showed that the applied UAV system equipped with a dual-camera set-up allows for the acquisition of thermal imagery with high spatial and temporal resolution that illustrates the small-scale heterogeneity of thermal surface properties. The UAV-based thermal imagery therefore provides the means for analysing patterns of LST and other surface properties with a high level of detail that cannot be obtained by traditional remote sensing methods.

Batch-Versuche zur Bestimmung der Sorption und Reaktionskinetik von fluoreszierenden Tracern

NASA Astrophysics Data System (ADS)

Vaitl, Tobias; Wohnlich, Stefan

2018-06-01

For many tracer experiments, prior determination of interaction between solid medium and used tracers is of major interest in order to achieve efficient, economic and successful field experiments. In the present study, three different types of batch experiments were performed with three fluorescent dyes (Na-Fluorescein, Amidorhodamin G and Tinopal CBS-X) and three different rock types (sandstone, claystone and limestone), to determine distribution coefficients and reaction kinetics. All three rock types were analysed for organic carbon content, specific surface area and mineralogical composition to identify the main sorption mechanisms. For all tracers, different sorption properties were found depending on the type of rock. The strongest sorption was observed for Tinopal CBS-X in contact with claystone. Only Na-Fluorescein showed sorption (albeit limited) in contact with the sandstones. The investigated limestones indicated a high sorption for the tracer Tinopal CBS-X. Regarding reaction kinetics, in most cases, thermodynamic equilibrium conditions were reached after two weeks.

Charged triblock copolymer self-assembly into charged micelles

NASA Astrophysics Data System (ADS)

Chen, Yingchao; Zhang, Ke; Zhu, Jiahua; Wooley, Karen; Pochan, Darrin; Department of Material Science; Engineering University of Delaware Team; Department of Chemistry Texas A&M University Collaboration

2011-03-01

Micelles were formed through the self-assembly of amphiphlic block copolymer poly(acrylic acid)-block-poly(methyl acrylate)-block-polystyrene (PAA-PMA-PS). ~Importantly, the polymer is complexed with diamine molecules in pure THF solution prior to water titration solvent processing-a critical aspect in the control of final micelle geometry. The addition of diamine triggers acid-base complexation ~between the carboxylic acid PAA side chains and amines. ~Remarkably uniform spheres were found to form close-packed patterns when forced into dried films and thin, solvated films when an excess of amine was used in the polymer assembly process. Surface properties and structural features of these hexagonal-packed spherical micelles with charged corona have been explored by various characterization methods including Transmission Electron Microscopy (TEM), cryogenic TEM, z-potential analysis and Dynamic Light Scattering. The forming mechanism for this pattern and morphology changes against external stimulate such as salt will be discussed.

Abrupt GaP/Si hetero-interface using bistepped Si buffer

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

Ping Wang, Y., E-mail: yanping.wang@insa-rennes.fr; Kuyyalil, J.; Nguyen Thanh, T.

We evidence the influence of the quality of the starting Si surface on the III-V/Si interface abruptness and on the formation of defects during the growth of III-V/Si heterogeneous crystal, using high resolution transmission electron microscopy and scanning transmission electron microscopy. GaP layers were grown by molecular beam epitaxy on vicinal Si (001). The strong effect of the Si substrate chemical preparation is first demonstrated by studying structural properties of both Si homoepitaxial layer and GaP/Si heterostructure. It is then shown that choosing adequate chemical preparation conditions and subsequent III-V regrowth conditions enables the quasi-suppression of micro-twins in the epilayer.more » Finally, the abruptness of GaP/Si interface is found to be very sensitive to the Si chemical preparation and is improved by the use of a bistepped Si buffer prior to III-V overgrowth.« less

Improved Adhesion of Gold Thin Films Evaporated on Polymer Resin: Applications for Sensing Surfaces and MEMS

PubMed Central

Moazzez, Behrang; O'Brien, Stacey M.; Merschrod S., Erika F.

2013-01-01

We present and analyze a method to improve the morphology and mechanical properties of gold thin films for use in optical sensors or other settings where good adhesion of gold to a substrate is of importance and where controlled topography/roughness is key. To improve the adhesion of thermally evaporated gold thin films, we introduce a gold deposition step on SU-8 photoresist prior to UV exposure but after the pre-bake step of SU-8 processing. Shrinkage and distribution of residual stresses, which occur during cross-linking of the SU-8 polymer layer in the post-exposure baking step, are responsible for the higher adhesion of the top gold film to the post-deposition cured SU-8 sublayer. The SU-8 underlayer can also be used to tune the resulting gold film morphology. Our promoter-free protocol is easily integrated with existing sensor microfabrication processes. PMID:23760086

ELECTRODEPOSITION OF NICKEL ON URANIUM

DOEpatents

Gray, A.G.

1958-08-26

A method is described for preparing uranium objects prior to nickel electroplating. The process consiats in treating the surface of the uranium with molten ferric chloride hexahydrate, at a slightiy elevated temperature. This treatment etches the metal surface providing a structure suitable for the application of adherent electrodeposits and at the same time plates the surface with a thin protective film of iron.

Cleanliness inspection tool for RSRM bond surfaces

NASA Technical Reports Server (NTRS)

Mattes, Robert A.

1995-01-01

Using optically stimulated electron emission (OSEE), Thiokol has monitored bond surfaces in process for contamination on the Redesigned Solid Rocket Motor (RSRM). This technique provides process control information to help assure bond surface quality and repeatability prior to bonding. This paper will describe OSEE theory of operation and the instrumentation implemented at Thiokol Corporation since 1987. Data from process hardware will be presented.

Surface Imaging Skin Friction Instrument and Method

NASA Technical Reports Server (NTRS)

Brown, James L. (Inventor); Naughton, Jonathan W. (Inventor)

1999-01-01

A surface imaging skin friction instrument allowing 2D resolution of spatial image by a 2D Hilbert transform and 2D inverse thin-oil film solver, providing an innovation over prior art single point approaches. Incoherent, monochromatic light source can be used. The invention provides accurate, easy to use, economical measurement of larger regions of surface shear stress in a single test.

Using the Sacramento soil moisture accounting model to provide short-term forecasts of surface runoff for daily decision making in nutrient management

USDA-ARS?s Scientific Manuscript database

Managing the timing of fertilizer and manure application is critical to protecting water quality in agricultural watersheds. When fertilizers and manures are applied at inopportune times (e.g., just prior to a rainfall event that produces surface runoff) the risk of surface water contamination is un...

DETECTION OF TOXICANT(S) ON BUILDING SURFACES FOLLOWING CHEMICAL ATTACK

EPA Science Inventory

A critical step prior to reoccupation of any facility following a chemical attack is monitoring for toxic compounds on surfaces within that facility. Low level detection of toxicant(s) is necessary to ensure that these compounds have been eliminated after building decontaminatio...

DETECTION OF TOXICANTS ON BUILDING SURFACES FOLLOWING CHEMICAL ATTACK

EPA Science Inventory

A critical step prior to reoccupation of any facility following a chemical attack will be the monitoring of toxic compounds on surfaces within that facility. Low level detection of toxicant(s) is necessary to ensure that these compounds have been eliminated after decontamination...

Generation of 3-D surface maps in waste storage silos using a structured light source

NASA Technical Reports Server (NTRS)

Burks, B. L.; Rowe, J. C.; Dinkins, M. A.; Christensen, B.; Selleck, C.; Jacoboski, D.; Markus, R.

1992-01-01

Surface contours inside the large waste storage tanks typical of the Department of Energy (DOE) complex are, in general, highly irregular. In addition to pipes and other pieces of equipment in the tanks, the surfaces may have features such as mounds, fissures, crystalline structures, and mixed solid and liquid forms. Prior to remediation activities, it will be necessary to characterize the waste to determine the most effective remediation approaches. Surface contour data will be required both prior to and during remediation. The use is described of a structured light source to generate 3-D surface contour maps of the interior of waste storage silos at the Feed Materials Production Center at Fernald, OH. The landscape inside these large waste storage tanks bears a strong resemblance to some of the landscapes that might be encountered during lunar or planetary exploration. Hence, these terrestrial 3-D mapping techniques may be directly applicable to extraterrestrial exploration. In further development, it will be demonstrated that these 3-D data can be used for robotic task planning just as 3-D surface contour data of a satellite could be used to plan maintenance tasks for a space-based servicing robot.

Damage of natural stone tablets exposed to exhaust gas under laboratory conditions

NASA Astrophysics Data System (ADS)

Farkas, Orsolya; Szabados, György; Török, Ákos

2016-04-01

Natural stone tablets were exposed to exhaust gas under laboratory conditions to assess urban stone damage. Cylindrical test specimens (3 cm in diameter) were made from travertine, non-porous limestone, porous limestone, rhyolite tuff, sandstone, andesite, granite and marble. The samples were exposed to exhaust gas that was generated from diesel engine combustion (engine type: RÁBA D10 UTSLL 160, EURO II). The operating condition of the internal combustion engine was: 1300 r/m (app 50%). The exhaust gas was diverted into a pipe system where the samples were placed perpendicular to main flow for 1, 2, 4, 8 and 10 hours, respectively. The exhaust emission was measured by using AVL particulate measurement technology; filter paper method (AVL 415). The stone samples were documented and selective parameters were measured prior to and after exhaust gas exposure. Density, volume, ultrasonic pulse velocity, mineral composition and penetration depth of emission related particulate matter were recorded. The first results indicate that after 10 hours of exposure significant amount of particulate matter deposited on the stone surface independently from the surface properties and porosity. The black soot particles uniformly covered all types of stones, making hard to differentiate the specimens.

A model system to mimic environmentally active surface film roughness and hydrophobicity.

PubMed

Grant, Jacob S; Shaw, Scott K

2017-10-01

This work presents the development and initial assessment of a laboratory platform to allow quantitative studies on model urban films. The platform consists of stearic acid and eicosane mixtures that are solution deposited from hexanes onto smooth, solid substrates. We show that this model has distinctive capabilities to better mimic a naturally occurring film's morphology and hydrophobicity, two important parameters that have not previously been incorporated into model film systems. The physical and chemical properties of the model films are assessed using a variety of analytical instruments. The film thickness and roughness are probed via atomic force microscopy while the film composition, wettability, and water uptake are analyzed by Fourier transform infrared spectroscopy, contact angle goniometry, and quartz crystal microbalance, respectively. Simulated environmental maturation is achieved by exposing the film to regulated amounts of UV/ozone. Ultimately, oxidation of the film is monitored by the analytical techniques mentioned above and proceeds as expected to produce a utile model film system. Including variable roughness and tunable surface coverage results in several key advantages over prior model systems, and will more accurately represent native urban film behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

Holistic Contract Administration in Army Forces Abroad

DTIC Science & Technology

2016-10-01

Defense (DoD) civil- ian personnel—i.e., 1910 Quality Assurance Specialist, 1102 Contract Specialist, and 1103 Industrial Property Management Specialist... 1103 -series civilian property ad- ministrators throughout ACC, the battalion experienced diffi- culties hiring for these positions during its deployment...tasks. Counting on 1103 support, ACOs received minimal property training prior to deploy- ment. This proved to be a major setback as ACOs struggled