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Sample records for active surface processes

  1. Imaging Active Surface Processes in Barnacle Adhesive Interfaces.

    PubMed

    Golden, Joel P; Burden, Daniel K; Fears, Kenan P; Barlow, Daniel E; So, Christopher R; Burns, Justin; Miltenberg, Benjamin; Orihuela, Beatriz; Rittshof, Daniel; Spillmann, Christopher M; Wahl, Kathryn J; Tender, Leonard M

    2016-01-19

    Surface plasmon resonance imaging (SPRI) and voltammetry were used simultaneously to monitor Amphibalanus (=Balanus) amphitrite barnacles reattached and grown on gold-coated glass slides in artificial seawater. Upon reattachment, SPRI revealed rapid surface adsorption of material with a higher refractive index than seawater at the barnacle/gold interface. Over longer time periods, SPRI also revealed secretory activity around the perimeter of the barnacle along the seawater/gold interface extending many millimeters beyond the barnacle and varying in shape and region with time. Ex situ experiments using attenuated total reflectance infrared (ATR-IR) spectroscopy confirmed that reattachment of barnacles was accompanied by adsorption of protein to surfaces on similar time scales as those in the SPRI experiments. Barnacles were grown through multiple molting cycles. While the initial reattachment region remained largely unchanged, SPRI revealed the formation of sets of paired concentric rings having alternately darker/lighter appearance (corresponding to lower and higher refractive indices, respectively) at the barnacle/gold interface beneath the region of new growth. Ex situ experiments coupling the SPRI imaging with optical and FTIR microscopy revealed that the paired rings coincide with molt cycles, with the brighter rings associated with regions enriched in amide moieties. The brighter rings were located just beyond orifices of cement ducts, consistent with delivery of amide-rich chemistry from the ducts. The darker rings were associated with newly expanded cuticle. In situ voltammetry using the SPRI gold substrate as the working electrode revealed presence of redox active compounds (oxidation potential approx 0.2 V vs Ag/AgCl) after barnacles were reattached on surfaces. Redox activity persisted during the reattachment period. The results reveal surface adsorption processes coupled to the complex secretory and chemical activity under barnacles as they construct

  2. Carbon activation process for increased surface accessibility in electrochemical capacitors

    DOEpatents

    Doughty, Daniel H.; Eisenmann, Erhard T.

    2001-01-01

    A process for making carbon film or powder suitable for double capacitor electrodes having a capacitance of up to about 300 F/cm.sup.3 is disclosed. This is accomplished by treating in aqueous nitric acid for a period of about 5 to 15 minutes thin carbon films obtained by carbonizing carbon-containing polymeric material having a high degree of molecular directionality, such as polyimide film, then heating the treated carbon film in a non-oxidizing atmosphere at a non-graphitizing temperature of at least 350.degree. C. for about 20 minutes, and repeating alternately the nitric acid step and the heating step from 7 to 10 times. Capacitors made with this carbon may find uses ranging from electronic devices to electric vehicle applications.

  3. Influence of process parameters on the surface and chemical properties of activated carbon obtained from biochar by chemical activation.

    PubMed

    Angın, Dilek; Altintig, Esra; Köse, Tijen Ennil

    2013-11-01

    Activated carbons were produced from biochar obtained through pyrolysis of safflower seed press cake by chemical activation with zinc chloride. The influences of process variables such as the activation temperature and the impregnation ratio on textural and chemical-surface properties of the activated carbons were investigated. Also, the adsorptive properties of activated carbons were tested using methylene blue dye as the targeted adsorbate. The experimental data indicated that the adsorption isotherms are well described by the Langmuir equilibrium isotherm equation. The optimum conditions resulted in activated carbon with a monolayer adsorption capacity of 128.21 mg g(-1) and carbon content 76.29%, while the BET surface area and total pore volume corresponded to 801.5m(2)g(-1) and 0.393 cm(3)g(-1), respectively. This study demonstrated that high surface area activated carbons can be prepared from the chemical activation of biochar with zinc chloride as activating agents.

  4. Role of Oxygen as Surface-Active Element in Linear GTA Welding Process

    NASA Astrophysics Data System (ADS)

    Yadaiah, Nirsanametla; Bag, Swarup

    2013-11-01

    Although the surface-active elements such as oxygen and sulfur have an adverse effect on momentum transport in liquid metals during fusion welding, such elements can be used beneficially up to a certain limit to increase the weld penetration in the gas tungsten arc (GTA) welding process. The fluid flow pattern and consequently the weld penetration and width change due to a change in coefficient of surface tension from a negative value to a positive value. The present work is focused on the analysis of possible effects of surface-active elements to change the weld pool dimensions in linear GTA welding. A 3D finite element-based heat transfer and fluid flow model is developed to study the effect of surface-active elements on stainless steel plates. A velocity in the order of 180 mm/s due to surface tension force is estimated at an optimum concentration of surface-active elements. Further, the differential evolution-based global optimization algorithm is integrated with the numerical model to estimate uncertain model parameters such as arc efficiency, effective arc radius, and effective values of material properties at high temperatures. The effective values of thermal conductivity and viscosity are estimated to be enhanced nine and seven times, respectively, over corresponding room temperature values. An error analysis is also performed to find out the overall reliability of the computed results, and a maximum reliability of 0.94 is achieved.

  5. Activity of processes on the visible surfaces of Solar System bodies

    NASA Astrophysics Data System (ADS)

    Vidmachenko, A. P.

    2016-10-01

    We consider the physical processes on the surfaces of Solar System bodies, which lead to visible changes in their reflective characteristics. It is shown that each body in the Solar system has a set of chemical elements and their compounds, converting of which indicates significant activity in such a significant temperature change range from 700 K (for Mercury) to 30 K for Pluto. That is, all objects in the Solar system show a significant activity. However, they are very individual for the list and the type of the processes that take place on each body in the Solar system.

  6. Mechanism of the activation process for the formation of a surface-conduction electron-emitter

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Takeo; Okuda, Masahiro; Arai, Yutaka; Miyata, Hirokatsu

    2016-01-01

    The major role of the chemical reaction between a silica substrate and deposited carbon in the activation process for the formation of a surface-conduction electron emitter (SCE) is investigated. The SCE emits electrons by the tunneling effect when an electric field is applied across a nanoscale gap. The nanogap is spontaneously formed by the activation process, wherein a pulse voltage is applied between a pair of electrodes, which are separated by a narrow gap inside a vacuum chamber in the presence of hydrocarbons. At the gap, two elemental processes compete; the deposition of carbon by the electron-induced decomposition of hydrocarbons and the consumption of carbon by reaction with the silica substrate. The balance of the dynamics of the two processes, which simply depends on the temperature at the gap, is responsible for the spontaneous determination of the width of the nanogap. The calculation based on the model that involves the two competitive processes agrees with the experimental results on the activation process.

  7. Optimization of permeabilization process of yeast cells for catalase activity using response surface methodology

    PubMed Central

    Trawczyńska, Ilona; Wójcik, Marek

    2015-01-01

    Biotransformation processes accompanied by whole yeast cells as biocatalyst are a promising area of food industry. Among the chemical sanitizers currently used in food technology, hydrogen peroxide is a very effective microbicidal and bleaching agent. In this paper, permeabilization has been applied to Saccharomyces cerevisiae yeast cells aiming at increased intracellular catalase activity for decomposed H2O2. Ethanol, which is non-toxic, biodegradable and easily available, has been used as permeabilization factor. Response surface methodology (RSM) has been applied in determining the influence of different parameters on permeabilization process. The aim of the study was to find such values of the process parameters that would yield maximum activity of catalase during decomposition of hydrogen peroxide. The optimum operating conditions for permeabilization process obtained by RSM were as follows: 53% (v/v) of ethanol concentration, temperature of 14.8 °C and treatment time of 40 min. After permeabilization, the activity of catalase increased ca. 40 times and its maximum value equalled to 4711 U/g. PMID:26019618

  8. Effect of Surface-active Additives on Physical Properties of Slurries of Vapor-process Magnesium

    NASA Technical Reports Server (NTRS)

    Pinns, Murray L

    1955-01-01

    The presence of 3 to 5 percent surface-active additive gave the lowest Brookfield apparent viscosity, plastic viscosity, and yield value that were obtained for slurry fuels containing approximately 50 percent vapor-process magnesium in JP-1 fuel. The slurries settled little and were easily remixed. A polyoxyethylene dodecyl alcohol was the most effective of 13 additives tested in reducing the Brookfield apparent viscosity and the yield value of the slurry. The seven most effective additives all had a hydroxyl group plus an ester or polyoxethylene group in the molecule. The densities of some of the slurries were measured.

  9. Metallization Process of a Polyimide Surface with Palladium-Free Activation for Electronic Field Applications

    NASA Astrophysics Data System (ADS)

    Li, Libo; Ma, Yue; Xie, Jingchen; Yang, Xiuchun; Wang, Heng; Tian, Haiyan; Mu, Hongjing; Wang, Wentao

    2015-10-01

    A new copper plating bath without Pd activation for electroless deposition on polyimide (PI) film is reported. The characteristics of Cu coatings on the PI via electroless plating and the effects of operating parameters on the coating coverage are discussed. The pre-treatment and plating processes are further optimized based on orthogonal experiment methods, involving variations of multiple process parameters. The electroless copper coating was characterized by scanning electron microscopy and atomic force microscopy, while the composition and crystalline structure are estimated by energy dispersive spectrometer and x-ray diffraction, respectively. These results show that the crystalline copper layer on the PI surface after electroless plating is dense, continuous and uniform. The joint tensile experiment is used to measure the adhesive strength of the coating with palladium-free and palladium activation, and the former is higher. Furthermore, the pre-treatment method proposed in this work without using palladium compounds is considered to be environmentally friendly. In addition, it provides a new concept of electroless Cu plating on the PI, which is generally difficult to plate due to its hydrophobic nature.

  10. Ultrahigh surface area carbon from carbonated beverages. Combining self-templaing process and in situ activation

    SciTech Connect

    Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua; Dai, Sheng

    2015-05-11

    Ultrahigh surface area carbons (USACs, e.g., >2000 m2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. This strategy covers various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, andFanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g-1) even at a scan rate of 1000 mV s-1. Thus, a simple and efficient strategy to USACs has been presented.

  11. Ultrahigh surface area carbon from carbonated beverages. Combining self-templaing process and in situ activation

    DOE PAGES

    Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua; ...

    2015-05-11

    Ultrahigh surface area carbons (USACs, e.g., >2000 m2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. This strategy coversmore » various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, andFanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g-1) even at a scan rate of 1000 mV s-1. Thus, a simple and efficient strategy to USACs has been presented.« less

  12. Characterization of the surface changes during the activation process of erbium/erbium oxide for hydrogen storage.

    SciTech Connect

    Zavadil, Kevin Robert; Snow, Clark Sheldon; Ohlhausen, James Anthony; Brumbach, Michael Todd

    2010-10-01

    Erbium is known to effectively load with hydrogen when held at high temperature in a hydrogen atmosphere. To make the storage of hydrogen kinetically feasible, a thermal activation step is required. Activation is a routine practice, but very little is known about the physical, chemical, and/or electronic processes that occur during Activation. This work presents in situ characterization of erbium Activation using variable energy photoelectron spectroscopy at various stages of the Activation process. Modification of the passive surface oxide plays a significant role in Activation. The chemical and electronic changes observed from core-level and valence band spectra will be discussed along with corroborating ion scattering spectroscopy measurements.

  13. Process effects on activated carbon with large specific surface area from corn cob.

    PubMed

    Cao, Qing; Xie, Ke-Chang; Lv, Yong-Kang; Bao, Wei-Ren

    2006-01-01

    The main factors that affect the large specific surface area (SSA) of the activated carbon from agricultural waste corn cobs were studied by chemically activated method with solution of KOH and soap which acted as surfactant. The experiment showed that not only the activation temperature, activation time and the mass ratio of KOH to the carbonized material, but also the activated methods using activator obviously influenced the SSA of activated carbon. The experimental operating conditions were as follows: the carbonized temperature being 450 degrees C and keeping time being 4 h using N2 as protective gas; the activation temperature being 850 degrees C and holding time being 1.2 h; the mass ratio of KOH to carbonized material being 4.0; the time of soaking carbonized material in the solution of KOH and soap being 30 min. Under the optimal conditions, the SSA of activated carbon from corn cobs reached 2700 m2/g. And the addition of the soap as surfactant may shorten the soaking time. The structure of the activated carbon prepared had narrow distribution of pore size and the micro-pores accounted for 78%. The advantages of the method described were easy and feasible.

  14. Morphotectonic evolution of passive margins undergoing active surface processes: large-scale experiments using numerical models.

    NASA Astrophysics Data System (ADS)

    Beucher, Romain; Huismans, Ritske S.

    2016-04-01

    Extension of the continental lithosphere can lead to the formation of a wide range of rifted margins styles with contrasting tectonic and geomorphological characteristics. It is now understood that many of these characteristics depend on the manner extension is distributed depending on (among others factors) rheology, structural inheritance, thermal structure and surface processes. The relative importance and the possible interactions of these controlling factors is still largely unknown. Here we investigate the feedbacks between tectonics and the transfers of material at the surface resulting from erosion, transport, and sedimentation. We use large-scale (1200 x 600 km) and high-resolution (~1km) numerical experiments coupling a 2D upper-mantle-scale thermo-mechanical model with a plan-form 2D surface processes model (SPM). We test the sensitivity of the coupled models to varying crust-lithosphere rheology and erosional efficiency ranging from no-erosion to very efficient erosion. We discuss how fast, when and how the topography of the continents evolves and how it can be compared to actual passive margins escarpment morphologies. We show that although tectonics is the main factor controlling the rift geometry, transfers of masses at the surface affect the timing of faulting and the initiation of sea-floor spreading. We discuss how such models may help to understand the evolution of high-elevated passive margins around the world.

  15. Impact-induced seismic activity on asteroid 433 Eros: a surface modification process.

    PubMed

    Richardson, James E; Melosh, H Jay; Greenberg, Richard

    2004-11-26

    High-resolution images of the surface of asteroid 433 Eros revealed evidence of downslope movement of a loose regolith layer, as well as the degradation and erasure of small impact craters (less than approximately 100 meters in diameter). One hypothesis to explain these observations is seismic reverberation after impact events. We used a combination of seismic and geomorphic modeling to analyze the response of regolith-covered topography, particularly craters, to impact-induced seismic shaking. Applying these results to a stochastic cratering model for the surface of Eros produced good agreement with the observed size-frequency distribution of craters, including the paucity of small craters.

  16. Optimization of process variables by response surface methodology for malachite green dye removal using lime peel activated carbon

    NASA Astrophysics Data System (ADS)

    Ahmad, Mohd Azmier; Afandi, Nur Syahidah; Bello, Olugbenga Solomon

    2015-04-01

    This study investigates the adsorptive removal of malachite green (MG) dye from aqueous solutions using chemically modified lime-peel-based activated carbon (LPAC). The adsorbent prepared was characterized using FTIR, SEM, Proximate analysis and BET techniques, respectively. Central composite design (CCD) in response surface methodology (RSM) was used to optimize the adsorption process. The effects of three variables: activation temperature, activation time and chemical impregnation ratio (IR) using KOH and their effects on percentage of dye removal and LPAC yield were investigated. Based on CCD design, quadratic models and two factor interactions (2FI) were developed correlating the adsorption variables to the two responses. Analysis of variance (ANOVA) was used to judge the adequacy of the model. The optimum conditions of MG dye removal using LPAC are: activation temperature (796 °C), activation time (1.0 h) and impregnation ratio (2.6), respectively. The percentage of MG dye removal obtained was 94.68 % resulting in 17.88 % LPAC yield. The percentage of error between predicted and experimental results for the removal of MG dye is 0.4 %. Model prediction was in good agreement with experimental results and LPAC was found to be effective in removing MG dye from aqueous solution.

  17. New Carbon Activation Process for Increased Surface Accessibility in Electrochemical Capacitors

    SciTech Connect

    Doughty, Daniel H.; Eisenmann, Erhard T.

    1999-03-16

    A process for making carbon film or powder suitable for double capacitor electrodes having a capacitance of up to about 300 F/cm{sup 3} is disclosed. This is accomplished by treating in aqueous nitric acid for a period of about 5 to 15 minutes thin carbon films obtained by carbonizing carbon-containing polymeric material having a high degree of molecular directionality, such as polyimide film, then heating the treated carbon film in a non-oxidizing atmosphere at a non-graphitizing temperature of at least 350 C for about 20 minutes, and repeating alternately the nitric acid step and the heating step from 7 to 10 times. Capacitors made with this carbon may find uses ranging from electronic devices to electric vehicle applications.

  18. Influence of the water molecules near surface of viral protein on virus activation process

    NASA Astrophysics Data System (ADS)

    Shepelenko, S. O.; Salnikov, A. S.; Rak, S. V.; Goncharova, E. P.; Ryzhikov, A. B.

    2009-06-01

    The infection of a cell with influenza virus comprises the stages of receptor binding to the cell membrane, endocytosis of virus particle, and fusion of the virus envelope and cell endosome membrane, which is determined by the conformational changes in hemagglutinin, a virus envelope protein, caused by pH decrease within the endosome. The pH value that induces conformation rearrangements of hemagglutinin molecule considerably varies for different influenza virus strains, first and foremost, due to the differences in amino acid structure of the corresponding proteins. The main goal of this study was to construct a model making it possible to assess the critical pH value characterizing the fusogenic activity of influenza virus hemagglutinin from the data on hemagglutinin structure and experimental verification of this model. Under this model, we assume that when the electrostatic force between interacting hemagglutinin molecules in the virus envelop exceeds a certain value, the hemagglutinin HA1 subunits are arranged so that they form a cavity sufficient for penetration of water molecules. This event leads to an irreversible hydration of the inner fragments of hemagglutinin molecule in a trimer and to the completion of conformational changes. The geometry of electrostatic field in hemagglutinin trimer was calculated taking into account the polarization effects near the interface of two dielectrics, aqueous medium and protein macromolecule. The critical pH values for the conformational changes in hemagglutinin were measured by the erythrocyte hemolysis induced by influenza virus particles when decreasing pH. The critical pH value conditionally separating the pH range into the regions with and without the conformational changes was calculated for several influenza virus H1N1 and H3N2 strains based on the data on the amino acid structure of the corresponding hemagglutinin molecules. Comparison of the theoretical and experimental values of critical pH values for

  19. Simulation of surface processes

    PubMed Central

    Jónsson, Hannes

    2011-01-01

    Computer simulations of surface processes can reveal unexpected insight regarding atomic-scale structure and transitions. Here, the strengths and weaknesses of some commonly used approaches are reviewed as well as promising avenues for improvements. The electronic degrees of freedom are usually described by gradient-dependent functionals within Kohn–Sham density functional theory. Although this level of theory has been remarkably successful in numerous studies, several important problems require a more accurate theoretical description. It is important to develop new tools to make it possible to study, for example, localized defect states and band gaps in large and complex systems. Preliminary results presented here show that orbital density-dependent functionals provide a promising avenue, but they require the development of new numerical methods and substantial changes to codes designed for Kohn–Sham density functional theory. The nuclear degrees of freedom can, in most cases, be described by the classical equations of motion; however, they still pose a significant challenge, because the time scale of interesting transitions, which typically involve substantial free energy barriers, is much longer than the time scale of vibrations—often 10 orders of magnitude. Therefore, simulation of diffusion, structural annealing, and chemical reactions cannot be achieved with direct simulation of the classical dynamics. Alternative approaches are needed. One such approach is transition state theory as implemented in the adaptive kinetic Monte Carlo algorithm, which, thus far, has relied on the harmonic approximation but could be extended and made applicable to systems with rougher energy landscape and transitions through quantum mechanical tunneling. PMID:21199939

  20. Landfill leachate treatment using powdered activated carbon augmented sequencing batch reactor (SBR) process: optimization by response surface methodology.

    PubMed

    Aziz, Shuokr Qarani; Aziz, Hamidi Abdul; Yusoff, Mohd Suffian; Bashir, Mohammed J K

    2011-05-15

    In this study, landfill leachate was treated by using the sequencing batch reactor (SBR) process. Two types of the SBR, namely non-powdered activated carbon and powdered activated carbon (PAC-SBR) were used. The influence of aeration rate and contact time on SBR and PAC-SBR performances was investigated. Removal efficiencies of chemical oxygen demand (COD), colour, ammoniacal nitrogen (NH(3)-N), total dissolved salts (TDS), and sludge volume index (SVI) were monitored throughout the experiments. Response surface methodology (RSM) was applied for experimental design, analysis and optimization. Based on the results, the PAC-SBR displayed superior performance in term of removal efficiencies when compared to SBR. At the optimum conditions of aeration rate of 1L/min and contact time of 5.5h the PAC-SBR achieved 64.1%, 71.2%, 81.4%, and 1.33% removal of COD, colour, NH(3)-N, and TDS, respectively. The SVI value of PAC-SBR was 122.2 mL/g at optimum conditions.

  1. Surface processes on Venus

    NASA Technical Reports Server (NTRS)

    Arvidson, R. E.

    1992-01-01

    Magellan synthetic aperture radar (SAR) and altimetry data were analyzed to determine the nature and extent of surface modification for venusian plains in the Sedna Planitia, Alpha Regio, and western Ovda Regio areas. Specific cross sections derived from the SAR data were also compared to similar data for dry terrestrial basaltic lava flows (Lunar Crater and Cima volcanic fields) and playas (Lunar and Lavic Lakes) for which microtopographic profiles (i.e., quantitative roughness information) were available.

  2. Active seismic sources as a proxy for seismic surface processes: An example from the 2012 Tongariro volcanic eruptions, New Zealand

    NASA Astrophysics Data System (ADS)

    Jolly, A. D.; Lokmer, I.; Kennedy, B.; Keys, H. J. R.; Proctor, J.; Lyons, J. J.; Jolly, G. E.

    2014-10-01

    The 6 August 2012 eruption from Tongariro volcano's Te Maari vent comprised a complex sequence of events including at least 4 eruption pulses, a large chasm collapse, and a debris avalanche (volume of ~ 7 × 105 m3) that propagated ~ 2 km beyond the eruptive vent. The eruption was poorly observed, being obscured by night time darkness, and the eruption timing must be unravelled instead from a complex seismic record that includes discrete volcanic earthquakes, a sequence of low to moderate level spasmodic tremor and an intense burst of seismic and infrasound activity that marked the eruption onset. We have discriminated the evolution of the complex surface activity by comparing active seismic source data to the seismic sequence in a new cross correlation source location approach. We dropped 11 high impact masses from helicopter to generate a range of active seismic sources in the vicinity of the eruption vent, chasm, and debris avalanche areas. We obtained 8 successful drops having an impact energy ranging from 3 to 9 × 106 Nm producing observable seismic signals to a distance of 5 to 10 km and having good signal to noise characteristics in the 3-12 Hz range. For the 8 drops, we picked first-P arrival times and calculated amplitude spectra for a uniform set of four stations. We then compared these proxy source excitations to the natural eruption and pre-eruption data using a moving window cross correlation approach. From the correlation processing, we obtain a best matched source position in the near vent region for the eruption period and significant down channel excitations during both the pre and post eruption periods. The total seismic energy release calculated from the new method is ~ 8 × 1011 Nm, similar to an independently estimated calculation based on the radiated seismic energy. The new energy estimate may be more robust than those calculated from standard seismic radiation equations, which may include uncertainties about the path and site effects. The

  3. Enhancement on photocatalytic activity of an amorphous titanium oxide film with nano-textured surface by selective-fluorination etching process

    SciTech Connect

    Shih, Pin-Chun; Huang, Cheng-Hao; Chen, Tai-Hong; Lai, Li-Wen; Lu, Yi-Shan; Liu, Day-Shan

    2014-04-01

    Highlights: • The amorphous TiO{sub x} film surface was modified via selective fluorination etching process. • The resulting nano-textured surface markedly enriched the specific surface area and surface acidity. • The photocatalytic activity was comparable to an annealed TiO{sub x} film with anatase structure. - Abstract: A selective-fluorination etching process achieved by an UV light pre-irradiation and the subsequently fluorination etching was developed to enhance the photocatalytic activity of a low-temperature deposited amorphous titanium oxide (a-TiO{sub x}) film. Textured surface on the a-TiO{sub x} films formed by this process were investigated using atomic force microscope and field emission scanning electron microscope. Evidence of the fluorine ions introduced into the a-TiO{sub x} films was examined using Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy. The etching thickness of the a-TiO{sub x} film was found to be deeply relevant to the film pre-irradiated by the UV light. An a-TiO{sub x} film with nano-textured surface, which was favorable to enlarge the specific surface area, thus was obtainable from the notable etching selectivity of the film pre-irradiated by UV light through a nano-sized mask. In addition, the surface acidity of the a-TiO{sub x} film was enhanced by the formation of the Ti-F chemical bonds originating from the fluorination etching process, which also was functional to facilitate the production of surface OH free radicals. Accordingly, the resulting fluorinated a-TiO{sub x} film with nano-textured surface performed a quality photocatalytic activity comparable to that of the high-temperature achieved TiO{sub x} film with anatase structures.

  4. The regulated cell surface zymogen activation of the proprotein convertase PC5A directs the processing of its secretory substrates.

    PubMed

    Mayer, Gaétan; Hamelin, Josée; Asselin, Marie-Claude; Pasquato, Antonella; Marcinkiewicz, Edwidge; Tang, Meiyi; Tabibzadeh, Siamak; Seidah, Nabil G

    2008-01-25

    The proprotein convertases are synthesized as zymogens that acquire activity upon autocatalytic removal of their NH(2)-terminal prosegment. Based on the convertase furin, to fold properly and gain activity, the convertases PC5A, PACE4, and PC7 are presumed to undergo two sequential prosegment cleavages in the endoplasmic reticulum and then in the trans-Golgi network. However, biochemical and immunocytochemical experiments revealed that mouse PC5A is complexed to its prosegment at the plasma membrane. This labeling is lost upon treatment with heparin and is increased by overexpressing members of the syndecan family and CD44, suggesting attachment of secreted PC5A-prosegment complex to heparan sulfate proteoglycans. Following stimulation of Y1 cells with adrenocorticotropic hormone or 8-bromo-cyclic AMP, the cell surface labeling of the prosegment of PC5A is greatly diminished, whereas the signal for mature PC5A is increased. Moreover, after stimulation, the protease activity of PC5A is enhanced, as evidenced by the cleavage of the PC5A substrates Lefty, ADAMTS-4, endothelial lipase, and PCSK9. Our data suggest a novel mechanism for PC5A activation and substrate cleavage at the cell surface, through a regulated removal of its prosegment. A similar mechanism may also apply to the convertase PACE4, thereby extending our knowledge of the molecular details of the zymogen activation and functions of these heparan sulfate proteoglycan-bound convertases.

  5. Climate Variability and Surface Processes in Tectonically Active Orogens: Insights From the Southern Central Andes and the Northwest Himalaya

    NASA Astrophysics Data System (ADS)

    Strecker, M. R.; Bookhagen, B.

    2008-12-01

    The Southern Central Andes of NW Argentina and the NW Himalaya are important orographic barriers that intercept moisture-bearing winds associated with monsoonal circulation. Changes in both atmospheric circulation systems on decadal to millennial timescales fundamentally influence differences in the amount and location of rainfall in both orogens. In India, the eastern arm of the monsoonal circulation draws moisture from the Bay of Bengal and transports humid air masses along the southern Himalayan front to the northwest. There, at the end of the monsoonal conveyer belt, rainfall is diminished and moisture typically does not reach far into the orogen interior. Similar conditions apply to the NW Argentine Andes, which are located within the precipitation regime of the South American Monsoon. Here, pronounced local relief blocks humid air masses from the Amazon region, resulting in extreme gradients in rainfall that leave the orogen interior dry. However, during negative ENSO years (La Niña) and intensified Indian Summer Monsoon years, moisture penetrates farther into the Andean and Himalayan orogens, respectively. Structurally pre- conditioned valley systems may enhance this process and funnel moisture far into the orogen interior. The greater availability of moisture increases runoff, lateral scouring of mountin streams, and ultimately triggers intensified hillslope processes on decadal to centennial timescales. In both environments, the scenario of intensified present-day surface processes and rates is analogous to protracted episodes of enhanced mass removal from hillslopes via deep-seated landslides during the early Holocene and late Pleistocene. Apparently, these episodes were also associated with transient storage of voluminous conglomerates and lacustrine deposits in narrow intermontane basins. Subsequently, these deposits were incised, partly removed, and the fluvial systems adjusted themselves to the pre-depositional base levels through a readjustment and

  6. Surface characterization of a Zr--V--Fe getter by XPS-SIMS: activation process and D/sub 2/O exposure

    SciTech Connect

    Ichimura, K.; Ashida, K.; Watanabe, K.

    1985-03-01

    To apply hydrogen storage materials (getters) to tritium recovery and storage, it is important to understand the activation process of the getters and their pumping characteristics not only for tritium gas, but also impurity gases such as HTO. From this viewpoint, the activation process of the Zr--V--Fe getter (St-707, SAES Getters) and absorption process of D/sub 2/O were investigated with XPS-SIMS. An as-received getter surface was observed to be covered with H/sub 2/O, CO, O/sub 2/, and hydrocarbons. In addition, the getter components formed respective oxides on the surface. The activation, which consisted of vacuum heating above 500 /sup 0/C, caused the disappearance of the adsorbed impurities from the surface, forming a metallic surface consisting of Zr(87 at.%) and V(13 at.%). Exposure to D/sub 2/O vapor at 25 /sup 0/C resulted in the adsorption of D/sub 2/O as D/sub 2/O(a) and/or OD(a). In addition, a part of the surface was oxidized. Elevation of the exposure temperature to 300 /sup 0/C caused the disappearance of the D/sub 2/O(a) and/or OD(a). Consequently the O-coverage decreased, although the partially oxidized surface remained. We conclude that both Zr and V function as the active sites for the decomposition of D/sub 2/O(a) and/or OD(a). However, the Zr sites work more actively for the decomposition reaction than the V sites do. Consequently, these Zr sites determine the absorption rate.

  7. Implant surfaces and interface processes.

    PubMed

    Kasemo, B; Gold, J

    1999-06-01

    The past decades and current R&D of biomaterials and medical implants show some general trends. One major trend is an increased degree of functionalization of the material surface, better to meet the demands of the biological host system. While the biomaterials of the past and those in current use are essentially bulk materials (metals, ceramics, polymers) or special compounds (bioglasses), possibly with some additional coating (e.g., hydroxyapatite), the current R&D on surface modifications points toward much more complex and multifunctional surfaces for the future. Such surface modifications can be divided into three classes, one aiming toward an optimized three-dimensional physical microarchitecture of the surface (pore size distributions, "roughness", etc.), the second one focusing on the (bio) chemical properties of surface coatings and impregnations (ion release, multi-layer coatings, coatings with biomolecules, controlled drug release, etc.), and the third one dealing with the viscoelastic properties (or more generally the micromechanical properties) of material surfaces. These properties are expected to affect the interfacial processes cooperatively, i.e., there are likely synergistic effects between and among them: The surface is "recognized" by the biological system through the combined chemical and topographic pattern of the surface, and the viscoelastic properties. In this presentation, the development indicated above is discussed briefly, and current R&D in this area is illustrated with a number of examples from our own research. The latter include micro- and nanofabrication of surface patterns and topographies by the use of laser machining, photolithographic techniques, and electron beam and colloidal lithographies to produce controlled structures on implant surfaces in the size range 10 nm to 100 microns. Examples of biochemical modifications include mono- or lipid membranes and protein coatings on different surfaces. A new method to evaluate, e

  8. Ocean processes underlying surface clustering

    NASA Astrophysics Data System (ADS)

    Jacobs, Gregg A.; Huntley, Helga S.; Kirwan, A. D.; Lipphardt, Bruce L.; Campbell, Timothy; Smith, Travis; Edwards, Kacey; Bartels, Brent

    2016-01-01

    Ageostrophic ocean processes such as frontogenesis, submesoscale mixed-layer instabilities, shelf break fronts, and topographic interactions on the continental shelf produce surface-divergent flows that affect buoyant material over time. This study examines the ocean processes leading to clustering, i.e., the increase of material density over time, on the ocean surface. The time series of divergence along a material trajectory, the Lagrangian divergence (LD), is the flow property driving clustering. To understand the impacts of various ocean processes on LD, numerical ocean model simulations at different resolutions are analyzed. Although the relevant processes differ, patterns in clustering evolution from the deep ocean and the continental shelf bear similarities. Smaller-scale ocean features are associated with stronger surface divergence, and the surface material clustering is initially dominated by these features. Over time, the effect of these small-scale features becomes bounded, as material traverses small-scale regions of both positive and negative divergence. Lower-frequency flow phenomena, however, continue the clustering. As a result, clustering evolves from initial small-scale to larger-scale patterns.

  9. Space environment and lunar surface processes, 2

    NASA Technical Reports Server (NTRS)

    Comstock, G. M.

    1982-01-01

    The top few millimeters of a surface exposed to space represents a physically and chemically active zone with properties different from those of a surface in the environment of a planetary atmosphere. To meet the need or a quantitative synthesis of the various processes contributing to the evolution of surfaces of the Moon, Mercury, the asteroids, and similar bodies, (exposure to solar wind, solar flare particles, galactic cosmic rays, heating from solar radiation, and meteoroid bombardment), the MESS 2 computer program was developed. This program differs from earlier work in that the surface processes are broken down as a function of size scale and treated in three dimensions with good resolution on each scale. The results obtained apply to the development of soil near the surface and is based on lunar conditions. Parameters can be adjusted to describe asteroid regoliths and other space-related bodies.

  10. Linking mantle dynamics, plate tectonics and surface processes in the active plate boundary zones of eastern New Guinea (Invited)

    NASA Astrophysics Data System (ADS)

    Baldwin, S.; Moucha, R.; Fitzgerald, P. G.; Hoke, G. D.; Bermudez, M. A.; Webb, L. E.; Braun, J.; Rowley, D. B.; Insel, N.; Abers, G. A.; Wallace, L. M.; Vervoort, J. D.

    2013-12-01

    Eastern New Guinea lies within the rapidly obliquely converging Australian (AUS)- Pacific (PAC) plate boundary zone and is characterized by transient plate boundaries, rapidly rotating microplates and a globally significant geoid high. As the AUS plate moved northward in the Cenozoic, its leading edge has been a zone of subduction and arc accretion. The variety of tectonic settings in this region permits assessment of the complex interplay among mantle dynamics, plate tectonics, and surface processes. Importantly, the timescale of tectonic events (e.g., subduction, (U)HP exhumation, seafloor spreading) are within the valid bounds of mantle convection models. A record of changes in bathymetry and topography are preserved in high standing mountain belts, exhumed extensional gneiss domes and core complexes, uplifted coral terraces, and marine sedimentary basins. Global seismic tomography models indicate accumulation of subducted slabs beneath eastern New Guinea at the bottom of the upper mantle (i.e., <660km depth). Some of the deeply subducted material may indeed be buoyant subducted AUS continental margin (to depths of ~250-300 km), as well as subducted continental material that has reached the point of no return (i.e., > 250-300 km). Preliminary global-scale backward advected mantle convection models, driven by density inferred from joint seismic-geodynamic tomography models, exhibit large-scale flow associated with these subducted slab remnants and predict the timing and magnitude (up to 1500 m) of dynamic topography change (both subsidence and uplift) since the Oligocene. In this talk we will explore the effects of large-scale background mantle flow and plate tectonics on the evolution of topography and bathymetry in eastern New Guinea, and discuss possible mechanisms to explain basin subsidence and surface uplift in the region.

  11. Optimization of Cu/activated carbon catalyst in low temperature selective catalytic reduction of NO process using response surface methodology.

    PubMed

    Amanpour, Javad; Salari, Dariush; Niaei, Aligholi; Mousavi, Seyed Mahdi; Panahi, Parvaneh Nakhostin

    2013-01-01

    Preparation of Cu/Activated Carbon (Cu/AC) catalyst was optimized for low temperature selective catalytic reduction of NO by using response surface methodology. A central composite design (CCD) was used to investigate the effects of three independent variables, namely pre-oxidization degree (HNO3%), Cu loading (wt.%) and calcination temperature on NO conversion efficiency. The CCD was consisted of 20 different preparation conditions of Cu/AC catalysts. The prepared catalysts were characterized by XRD and SEM techniques. Predicting NO conversion was carried out using a second order model obtained from designed experiments and statistical software Minitab 14. Regression and Pareto graphic analysis showed that all of the chosen parameters and some interactions were effective on the NO conversion. The optimal values were pre-oxidization in 10.2% HNO3, 6.1 wt.% Cu loading and 480°C for calcination temperature. Under the optimum condition, NO conversion (94.3%) was in a good agreement with predicted value (96.12%).

  12. Synthesis of large surface area nano-sized BiVO{sub 4} by an EDTA-modified hydrothermal process and its enhanced visible photocatalytic activity

    SciTech Connect

    Sun Wanting; Xie Mingzheng; Jing Liqiang; Luan Yunbo; Fu Honggang

    2011-11-15

    In this work, monoclinic scheelite-type BiVO{sub 4} nanoparticle with large surface area has been successfully synthesized, using Bi(NO{sub 3}){sub 3} and NH{sub 4}VO{sub 3} as raw materials, through a hydrothermal process in the presence of ethylene diamine tetraacetic acid (EDTA). It is demonstrated that the nanoparticle size of as-prepared BiVO{sub 4} becomes small by decreasing hydrothermal temperature, shortening hydrothermal reaction time and increasing EDTA amount used. The resulting BiVO{sub 4} nanoparticle with large surface area exhibits a good photocatalytic performance for degrading phenol solution as a model organic pollutant under visible illumination. The key of this method is the chelating role of EDTA group in the synthetic process that it can greatly control the concentration of Bi{sup 3+}, leading to the growth inhibition of BiVO{sub 4} crystallite. The work provides a route for the synthesis of Bi-containing nano-sized composite oxides with large surface area. - Graphical abstract: High visible active nano-sized BiVO{sub 4} photocatalyst with large surface area is successfully synthesized, which is attributed to the chelating role of EDTA group inhibiting the growth of BiVO{sub 4} crystallites. Highlights: > Monoclinic scheelite-type BiVO{sub 4} nanoparticle with large surface area has been synthesized by a hydrothermal process. > Key of this method is the chelating role of EDTA group inhibiting the growth of BiVO{sub 4} crystallites. > Resulting nano-sized BiVO{sub 4} exhibits a good photocatalytic activity for degrading phenol under visible illumination.

  13. Identification of microbes from the surfaces of food-processing lines based on the flow cytometric evaluation of cellular metabolic activity combined with cell sorting.

    PubMed

    Juzwa, W; Duber, A; Myszka, K; Białas, W; Czaczyk, K

    2016-09-01

    In this study the design of a flow cytometry-based procedure to facilitate the detection of adherent bacteria from food-processing surfaces was evaluated. The measurement of the cellular redox potential (CRP) of microbial cells was combined with cell sorting for the identification of microorganisms. The procedure enhanced live/dead cell discrimination owing to the measurement of the cell physiology. The microbial contamination of the surface of a stainless steel conveyor used to process button mushrooms was evaluated in three independent experiments. The flow cytometry procedure provided a step towards monitoring of contamination and enabled the assessment of microbial food safety hazards by the discrimination of active, mid-active and non-active bacterial sub-populations based on determination of their cellular vitality and subsequently single cell sorting to isolate microbial strains from discriminated sub-populations. There was a significant correlation (r = 0.97; p < 0.05) between the bacterial cell count estimated by the pour plate method and flow cytometry, despite there being differences in the absolute number of cells detected. The combined approach of flow cytometric CRP measurement and cell sorting allowed an in situ analysis of microbial cell vitality and the identification of species from defined sub-populations, although the identified microbes were limited to culturable cells.

  14. Surface Processes and Hack's law

    NASA Astrophysics Data System (ADS)

    Walcott, R.

    2010-12-01

    Hack’s law describes the non-linear relationship between the area of a catchment and the length of the longest stream within it. First described in the 1950’s based on a small area in the Appalachians, more recent studies have suggested that this relationship is consistent for over 13 orders of magnitude. As a result Hack’s law is generally considered as one of the fundamental morphological relationships of geomorphology and much effort has been devoted to understanding its origins. This law suggests that catchments are scale independent, however, recent work has demonstrated that the form of catchments varies depending on the type of surface processes operating within the catchment. In this paper we analyse the relationship between hillslope processes and Hack’s law for catchments that range over several orders of magnitude in size in the Himalaya and Chile. We show that Hack’s law varies systematically depending on the mean slope of a catchment. As the dominant process that operates within a catchment also varies with slope and scales with catchment size our findings have important implications for the robustness of Hack’s law and the scale independence of catchments.

  15. Influence of multi-industrial activities on trace metal contamination: an approach towards surface water body in the vicinity of Dhaka Export Processing Zone (DEPZ).

    PubMed

    Ahmed, Golam; Miah, M Arzu; Anawar, Hossain M; Chowdhury, Didarul A; Ahmad, Jasim U

    2012-07-01

    Industrial wastewater discharged into aquatic ecosystems either directly or because of inadequate treatment of process water can increase the concentrations of pollutants such as toxic metals and others, and subsequently deteriorate water quality, environmental ecology and human health in the Dhaka Export Processing Zone (DEPZ), the largest industrial belt of 6-EPZ in Bangladesh. Therefore, in order to monitor the contamination levels, this study collected water samples from composite effluent points inside DEPZ and the surrounding surface water body connected to effluent disposal sites and determined the environmental hazards by chemical analysis and statistical approach. The water samples were analysed by inductively coupled plasma mass spectrometry to determine 12 trace metals such as As, Ag, Cr, Co, Cu, Li, Ni, Pb, Se, Sr, V and Zn in order to assess the influence of multi-industrial activities on metal concentrations. The composite effluents and surface waters from lagoons were characterized by a strong colour and high concentrations of biochemical oxygen demand, chemical oxygen demand, electrical conductivity, pH, total alkalinity, total hardness, total organic carbon, Turb., Cl(-), total suspended solids and total dissolved solids, which were above the limit of Bangladesh industrial effluent standards, but dissolved oxygen concentration was lower than the standard value. The measurement of skewness and kurtosis values showed asymmetric and abnormal distribution of the elements in the respective phases. The mean trend of variation was found in a decreasing order: Zn > Cu > Sr > Pb > Ni > Cr > Li > Co > V > Se > As > Ag in composite industrial effluents and Zn > Cu > Sr > Pb > Ni > Cr > Li > V > As > Ag > Co > Se in surface waters near the DEPZ. The strong correlations between effluent and surface water metal contents indicate that industrial wastewaters discharged from DEPZ have a strong influence on the contamination of the surrounding water bodies by toxic

  16. Active particles on curved surfaces

    NASA Astrophysics Data System (ADS)

    Fily, Yaouen; Baskaran, Aparna; Hagan, Michael

    Active systems have proved to be very sensitive to the geometry of their environment. This is often achieved by spending significant time at the boundary, probing its shape by gliding along it. I will discuss coarse graining the microscopic dynamics of self-propelled particles on a general curved surface to predict the way the density profile on the surface depends on its geometry. Beyond confined active particles, this formalism is a natural starting point to study objects that cannot leave the boundary at all, such as cells crawling on a curved substrate, animals running on uneven ground, or active colloids trapped at an interface.

  17. Active braze process

    SciTech Connect

    Levine, I.L.; Pike, R.A.

    1990-11-02

    Active metal bonding using Cusil (silver-copper) braze alloys is a well established method used at GE Neutron Devices (GEND) for bonding metal to metal, metal to ceramics, and ceramics to ceramics. However, there are many instances in which using a silver alloy for bonding is undesirable (e.g., in vacuum tube envelopes, or where sequential braze steps at different temperatures are required to complete an assembly). The Material and Processes Laboratory at GEND has discovered a new method of active brazing with non-silver alloys which has proved especially successful in ceramic-to-ceramic joints. This method has the added advantage of eliminating several steps which are required in conventional bonding techniques. 2 figs., 10 tabs.

  18. Response surface modeling and optimization of chromium(VI) removal from aqueous solution using Tamarind wood activated carbon in batch process.

    PubMed

    Sahu, J N; Acharya, Jyotikusum; Meikap, B C

    2009-12-30

    The present paper discusses response surface methodology (RSM) as an efficient approach for predictive model building and optimization of chromium adsorption on developed activated carbon. In this work the application of RSM is presented for optimizing the removal of Cr(VI) ions from aqua solutions using activated carbon as adsorbent. All experiments were performed according to statistical designs in order to develop the predictive regression models used for optimization. The optimization of adsorption of chromium on activated carbon was carried out to ensure a high adsorption efficiency at low adsorbent dose and high initial concentration of Cr(VI). While the goal of adsorption of chromium optimization was to improve adsorption conditions in batch process, i.e., to minimize the adsorbent dose and to increase the initial concentration of Cr(VI). In the adsorption experiments a laboratory developed Tamarind wood activated carbon made of chemical activation (zinc chloride) was used. A 2(4) full factorial central composite design experimental design was employed. Analysis of variance (ANOVA) showed a high coefficient of determination value (R(2)=0.928) and satisfactory prediction second-order regression model was derived. Maximum chromium removal efficiency was predicted and experimentally validated. The optimum adsorbent dose, temperature, initial concentration of Cr(VI) and initial pH of the Cr(VI) solution were found to be 4.3g/l, 32 degrees C, 20.15 mg/l and 5.41 respectively. Under optimal value of process parameters, high removal (>89%) was obtained for Cr(VI).

  19. Surface Processes of Faceted Growth

    NASA Technical Reports Server (NTRS)

    Chernov, A.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Atomic force microscopy and high precision optical interferometry allow to analyze the processes that are in the core of our present understanding of faceted crystal growth. Some of these processes will be reviewed. Recent experiments suggest that the Gibbs-Thomson Law (GTL) may not be applicable to the weakly fluctuating strongly polygonized steps, with low kink density. Propagation rate of a straight short step segment changes with the segment length much steeper than predicted by GTL. If the step fluctuations are still well developed, the typical transition length may be determined just by the radius of rounded comers of the polygonized step. If fluctuations do not have enough time to develop, the kinetic effects may be essential. Indeed, 'communications' between comers of a short straight step segment may occur and, thus, the GTL may be implemented only via kink exchange. E.g., dissolutions of this short segment at macroscopic equilibrium occurs as follows: The kinks are split from one comer as a result of fluctuations, and annihilate with kinks of the opposite sign generated by another comer. Similarly, an exchange via chain of kinks on a rough step is the mechanism to implement the GT Law. If there is a supersaturation with respect to a large crystal, the kinks not only diffuse along the step, but move back the generating comers. This 'wind' prevents communication between the comers and places upper limit supersaturation only below which GTL is applicable. Steps replace kinks in the 3D case, though, of course, another dimensionality brings about another physics. Another specific problem to think about is if fluctuations are always fast enough to provide enough kinks for linear dependence of step rate on supersaturation. Increasing azimuthal polygonization of growth hillocks is a sign of insufficient fluctuation rate. Morphological stability of vicinal faces is usually considered on the basis of mutually parallel steps. Azimuthal anisotropy and interlacing of

  20. Active Free Surface Density Maps

    NASA Astrophysics Data System (ADS)

    Çelen, S.

    2016-10-01

    Percolation problems were occupied to many physical problems after their establishment in 1957 by Broadbent and Hammersley. They can be used to solve complex systems such as bone remodeling. Volume fraction method was adopted to set some algorithms in the literature. However, different rate of osteoporosis could be observed for different microstructures which have the same mass density, mechanical stimuli, hormonal stimuli and nutrition. Thus it was emphasized that the bone might have identical porosity with different specific surfaces. Active free surface density of bone refers the used total area for its effective free surface. The purpose of this manuscript is to consolidate a mathematical approach which can be called as “active free surface density maps” for different surface patterns and derive their formulations. Active free surface density ratios were calculated for different Archimedean lattice models according to Helmholtz free energy and they were compared with their site and bond percolation thresholds from the background studies to derive their potential probability for bone remodeling.

  1. Surface studies of plasma processed Nb samples

    SciTech Connect

    Tyagi, Puneet V.; Doleans, Marc; Hannah, Brian S.; Afanador, Ralph; Stewart, Stephen; Mammosser, John; Howell, Matthew P; Saunders, Jeffrey W; Degraff, Brian D; Kim, Sang-Ho

    2015-01-01

    Contaminants present at top surface of superconducting radio frequency (SRF) cavities can act as field emitters and restrict the cavity accelerating gradient. A room temperature in-situ plasma processing technology for SRF cavities aiming to clean hydrocarbons from inner surface of cavities has been recently developed at the Spallation Neutron Source (SNS). Surface studies of the plasma-processed Nb samples by Secondary ion mass spectrometry (SIMS) and Scanning Kelvin Probe (SKP) showed that the NeO2 plasma processing is very effective to remove carbonaceous contaminants from top surface and improves the surface work function by 0.5 to 1.0 eV.

  2. Surface-Activated Coupling Reactions Confined on a Surface.

    PubMed

    Dong, Lei; Liu, Pei Nian; Lin, Nian

    2015-10-20

    Chemical reactions may take place in a pure phase of gas or liquid or at the interface of two phases (gas-solid or liquid-solid). Recently, the emerging field of "surface-confined coupling reactions" has attracted intensive attention. In this process, reactants, intermediates, and products of a coupling reaction are adsorbed on a solid-vacuum or a solid-liquid interface. The solid surface restricts all reaction steps on the interface, in other words, the reaction takes place within a lower-dimensional, for example, two-dimensional, space. Surface atoms that are fixed in the surface and adatoms that move on the surface often activate the surface-confined coupling reactions. The synergy of surface morphology and activity allow some reactions that are inefficient or prohibited in the gas or liquid phase to proceed efficiently when the reactions are confined on a surface. Over the past decade, dozens of well-known "textbook" coupling reactions have been shown to proceed as surface-confined coupling reactions. In most cases, the surface-confined coupling reactions were discovered by trial and error, and the reaction pathways are largely unknown. It is thus highly desirable to unravel the mechanisms, mechanisms of surface activation in particular, of the surface-confined coupling reactions. Because the reactions take place on surfaces, advanced surface science techniques can be applied to study the surface-confined coupling reactions. Among them, scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) are the two most extensively used experimental tools. The former resolves submolecular structures of individual reactants, intermediates, and products in real space, while the latter monitors the chemical states during the reactions in real time. Combination of the two methods provides unprecedented spatial and temporal information on the reaction pathways. The experimental findings are complemented by theoretical modeling. In particular, density

  3. High surface area carbon and process for its production

    DOEpatents

    Romanos, Jimmy; Burress, Jacob; Pfeifer, Peter; Rash, Tyler; Shah, Parag; Suppes, Galen

    2016-12-13

    Activated carbon materials and methods of producing and using activated carbon materials are provided. In particular, biomass-derived activated carbon materials and processes of producing the activated carbon materials with prespecified surface areas and pore size distributions are provided. Activated carbon materials with preselected high specific surface areas, porosities, sub-nm (<1 nm) pore volumes, and supra-nm (1-5 nm) pore volumes may be achieved by controlling the degree of carbon consumption and metallic potassium intercalation into the carbon lattice during the activation process.

  4. Geochemical processes at mineral surfaces

    SciTech Connect

    Davis, J.A.; Hayes, K.F.

    1986-01-01

    This volume includes 32 papers which were presented at a symposium on geochemical processes at mineral-water interfaces in 1985 and which bring to bear on this area a very wide range of expertise. The discontinuities in properties which occur at the mineral-water interface have profound effects on the movement of naturally occurring ions. Weathering and precipitation processes control the concentrations and speciation of ions in natural waters and the movements of these within the hydrosphere; both classes of processes take place at mineral-water interfaces. After an introductory overview, the book is divided into seven major sections, each dealing with one of the aspects of the processes occurring at the mineral-water interface. Five papers deal with the physical properties of the mineral-water interface; these represent a well-balanced mix of experimental and theoretical (mathematical modeling) work. Adsorption phenomena are dealt with in another five papers; these are largely experimental in character. Ion-exchange processes are discussed in four papers, one of which addresses the use of relaxation methods to study ion exchange kinetics at the microscopic level. Spectroscopic techniques (including electron-spin resonance and Moessbauer spectroscopy) are utilized in four papers. Chemical reactions, mainly redox processes, at mineral-water interfaces are treated in four papers, one of which deals with non-biological organic reactions. Solid-solution formation and equilibria are the subjects of another set of four articles, and the last group of papers deals with the processes involved in precipitation and dissolution, including weathering.

  5. Technique for surface oxidation of activated carbon

    SciTech Connect

    Sircar, S.; Golden, T.C.

    1987-10-27

    A method of activating a carbon adsorbent is described, which comprises oxidizing the surface of the carbon adsorbent with a mild oxidizing acid in the presence of a metal oxidation catalyst at an elevated temperature and boiling the mixture of the carbon adsorbent, mild oxidizing acid and metal oxidation catalyst to dryness. Then rinse the surface oxidizing carbon adsorbent with water; and dry the rinsed surface oxidized carbon adsorbent. In a process for the removal of water or carbon dioxide from a gas stream containing water or carbon dioxide of the type wherein the gas stream containing water or carbon dioxide is contacted with a solid phase adsorbent under pressure-swing adsorption or thermal-swing adsorption processing conditions, the improvement is described comprising utilizing an adsorbent produced by the activation of a carbon adsorbent. The activation comprises oxidizing the surface of the carbon adsorbent with a mold oxidizing acid in the presence of a metal oxidation catalyst at an elevated temperature and boiling the mixture of the carbon adsorbent, mild oxidizing acid and metal oxidation catalyst to dryness. Then rinse the surface oxidized carbon adsorbent with water; and dry the rinsed surface oxidized carbon adsorbent.

  6. Active and responsive polymer surfaces.

    PubMed

    Zhang, Jilin; Han, Yanchun

    2010-02-01

    A central challenge in polymer science today is creating materials that dynamically alter their structures and properties on demand, or in response to changes in their environment. Surfaces represent an attractive area of focus, since they exert disproportionately large effects on properties such as wettability, adhesiveness, optical appearance, and bioactivity, enabling pronounced changes in properties to be accomplished through subtle changes in interfacial structure or chemistry. In this critical review, we review the recent research progress into active and responsive polymer surfaces. The chief purpose of this article is to summarize the advanced preparation techniques and applications in this field from the past decade. This review should be of interest both to new scientists in this field and the interdisciplinary researchers who are working on "intelligent" polymer surfaces (117 references).

  7. Nitrate postdeposition processes in Svalbard surface snow

    NASA Astrophysics Data System (ADS)

    Björkman, Mats P.; Vega, Carmen P.; Kühnel, Rafael; Spataro, Francesca; Ianniello, Antonietta; Esposito, Giulio; Kaiser, Jan; Marca, Alina; Hodson, Andy; Isaksson, Elisabeth; Roberts, Tjarda J.

    2014-11-01

    The snowpack acts as a sink for atmospheric reactive nitrogen, but several postdeposition pathways have been reported to alter the concentration and isotopic composition of snow nitrate with implications for atmospheric boundary layer chemistry, ice core records, and terrestrial ecology following snow melt. Careful daily sampling of surface snow during winter (11-15 February 2010) and springtime (9 April to 5 May 2010) near Ny-Ålesund, Svalbard reveals a complex pattern of processes within the snowpack. Dry deposition was found to dominate over postdeposition losses, with a net nitrate deposition rate of (0.6 ± 0.2) µmol m-2 d-1 to homogeneous surface snow. At Ny-Ålesund, such surface dry deposition can either solely result from long-range atmospheric transport of oxidized nitrogen or include the redeposition of photolytic/bacterial emission originating from deeper snow layers. Our data further confirm that polar basin air masses bring 15N-depleted nitrate to Svalbard, while high nitrate δ(18O) values only occur in connection with ozone-depleted air, and show that these signatures are reflected in the deposited nitrate. Such ozone-depleted air is attributed to active halogen chemistry in the air masses advected to the site. However, here the Ny-Ålesund surface snow was shown to have an active role in the halogen dynamics for this region, as indicated by declining bromide concentrations and increasing nitrate δ(18O), during high BrO (low-ozone) events. The data also indicate that the snowpack BrO-NOx cycling continued in postevent periods, when ambient ozone and BrO levels recovered.

  8. Surface reactions in microelectronics process technology.

    PubMed

    Levitin, Galit; Hess, Dennis W

    2011-01-01

    Current integrated circuit (IC) manufacturing consists of more than 800 process steps, nearly all of which involve reactions at surfaces that significantly impact device yield and performance. From initial surface preparation through film deposition, patterning, etching, residue removal, and metallization, an understanding of surface reactions and interactions is critical to the successful continuous scaling, yield, and reliability of electronic devices. In this review, some of the most important surface reactions that drive the development of microelectronic device fabrication are described. The reactions discussed do not constitute comprehensive coverage of this topic in IC manufacture but have been selected to demonstrate the importance of surface/interface reactions and interactions in the development of new materials, processing sequences, and process integration challenges. Specifically, the review focuses on surface reactions related to surface cleaning/preparation, semiconductor film growth, dielectric film growth, metallization, and etching (dry and wet).

  9. Water surface capturing by image processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An alternative means of measuring the water surface interface during laboratory experiments is processing a series of sequentially captured images. Image processing can provide a continuous, non-intrusive record of the water surface profile whose accuracy is not dependent on water depth. More trad...

  10. Excimer laser surface processing of titanium

    SciTech Connect

    Jervis, T.R.; Hubbard, K.M.; Zocco, T.G.; Foster, L.; Nastasi, M.; Tesmer, J.R.

    1993-05-01

    We have examined the effect of laser surface processing of Ti alloys using pulsed excimer laser light at 248 nm. Thermal transformations of the surface are accomplished by heating the surface and rapid cooling. Alloying and formation of compounds can be obtained by melting and mixing surface layers into the material and by gas alloying. Multiple melting-resolidification cycles result in the inter-diffusion of surface layers in the liquid state and the diffusion of gas species into the material. The effect of alloying from both solid and gas sources and the effects of thermal transformations on the microstructure and surface hardness properties of these alloys will be examined.

  11. Excimer laser surface processing of titanium

    SciTech Connect

    Jervis, T.R.; Hubbard, K.M.; Zocco, T.G.; Foster, L.; Nastasi, M.; Tesmer, J.R.

    1993-01-01

    We have examined the effect of laser surface processing of Ti alloys using pulsed excimer laser light at 248 nm. Thermal transformations of the surface are accomplished by heating the surface and rapid cooling. Alloying and formation of compounds can be obtained by melting and mixing surface layers into the material and by gas alloying. Multiple melting-resolidification cycles result in the inter-diffusion of surface layers in the liquid state and the diffusion of gas species into the material. The effect of alloying from both solid and gas sources and the effects of thermal transformations on the microstructure and surface hardness properties of these alloys will be examined.

  12. Atomic Processes on Mineral Surfaces

    NASA Astrophysics Data System (ADS)

    Hillner, Paul Everett

    This thesis describes research using atomic force microscopy (AFM) to observe the growth and dissolution mechanisms of crystals. Chapter 1 starts with an overview of crystal growth theory and then outlines the impact of AFM on the field. Chapter 2 introduces the techniques of real-time AFM imaging of crystal growth and shows the strong preferential dissolution of material at defects. Chapter 3 expands the importance of crystal defects, showing the importance of spiral defects to the aqueous growth of calcite. Chapter 4 presents a rigorous analysis of step kinetics on calcite and shows that surface diffusion is not the controlling factor of growth rate. Chapter 5 examines the effect of solvent modifications on the growth morphology of spiral hillocks on calcite and also determines the mechanisms by which manmade and natural poisons stop crystal growth. Chapter 6 presents quantitative calcite spiral rotation rates and step velocities vs. supersaturation as well as contrasting the layer-spiral growth mechanism of calcite with the poly -nucleation growth mechanism of fluorite.

  13. Lunar soil and surface processes studies

    NASA Technical Reports Server (NTRS)

    Glass, B. P.

    1975-01-01

    Glass particles in lunar soil were characterized and compared to terrestrial analogues. In addition, useful information was obtained concerning the nature of lunar surface processes (e.g. volcanism and impact), maturity of soils and chemistry and heterogeneity of lunar surface material. It is felt, however, that the most important result of the study was that it demonstrated that the investigation of glass particles from the regolith of planetary bodies with little or no atmospheres can be a powerful method for learning about the surface processes and chemistry of planetary surfaces. Thus, the return of samples from other planetary bodies (especially the terrestrial planets and asteroids) using unmanned spacecraft is urged.

  14. Linking Deep Earth and Surface Processes

    NASA Astrophysics Data System (ADS)

    Cloetingh, Sierd; Willett, Sean D.

    2013-01-01

    One of the important developments in Earth science over the past decade has been recognition of the significance of linking deep Earth dynamic processes with surface and near-surface geologic processes [e.g., Braun, 2010]. Deep Earth research, encompassing fields such as seismology and mantle geodynamics, has traditionally operated distinctly from fields focusing on dynamics of the Earth's surface, such as sedimentology and geomorphology. However, these endeavors have in common the study of Earth's topography and the prediction of changes in its surface. Observables from surface studies, such as basin stratigraphy, geomorphology of landscapes, changes in surface elevation, and changes in sea level, provide some of the principal constraints on geodynamic and tectonic models. Conversely, deep geodynamic processes give rise to the topography, erosion, and sediment generation that are the basis of surface geology. Surface manifestations of deep geodynamic processes have significant societal impact by creating natural hazards, such as earthquakes and mass movements, and controlling the distribution of natural resources such as fossil fuels or geothermal energy. The relevance of research conducted in both the deep Earth and surface regimes is thus enhanced through a focus on their interaction.

  15. Bactericidal activity of biomimetic diamond nanocone surfaces.

    PubMed

    Fisher, Leanne E; Yang, Yang; Yuen, Muk-Fung; Zhang, Wenjun; Nobbs, Angela H; Su, Bo

    2016-03-17

    The formation of biofilms on implant surfaces and the subsequent development of medical device-associated infections are difficult to resolve and can cause considerable morbidity to the patient. Over the past decade, there has been growing recognition that physical cues, such as surface topography, can regulate biological responses and possess bactericidal activity. In this study, diamond nanocone-patterned surfaces, representing biomimetic analogs of the naturally bactericidal cicada fly wing, were fabricated using microwave plasma chemical vapor deposition, followed by bias-assisted reactive ion etching. Two structurally distinct nanocone surfaces were produced, characterized, and the bactericidal ability examined. The sharp diamond nanocone features were found to have bactericidal capabilities with the surface possessing the more varying cone dimension, nonuniform array, and decreased density, showing enhanced bactericidal ability over the more uniform, highly dense nanocone surface. Future research will focus on using the fabrication process to tailor surface nanotopographies on clinically relevant materials that promote both effective killing of a broader range of microorganisms and the desired mammalian cell response. This study serves to introduce a technology that may launch a new and innovative direction in the design of biomaterials with capacity to reduce the risk of medical device-associated infections.

  16. Integrated mold/surface-micromachining process

    SciTech Connect

    Barron, C.C.; Fleming, J.G.; Montague, S.; Sniegowski, J.J.; Hetherington, D.L.

    1996-03-01

    We detail a new monolithically integrated silicon mold/surface-micromachining process which makes possible the fabrication of stiff, high-aspect-ratio micromachined structures integrated with finely detailed, compliant structures. An important example, which we use here as our process demonstration vehicle, is that of an accelerometer with a large proof mass and compliant suspension. The proof mass is formed by etching a mold into the silicon substrate, lining the mold with oxide, filling it with mechanical polysilicon, and then planarizing back to the level of the substrate. The resulting molded structure is recessed into the substrate, forming a planar surface ideal for subsequent processing. We then add surface-micromachined springs and sense contacts. The principal advantage of this new monolithically integrated mold/surface-micromachining process is that it decouples the design of the different sections of the device: In the case of a sensitive accelerometer, it allows us to optimize independently the proof mass, which needs to be as large, stiff, and heavy as possible, and the suspension, which needs to be as delicate and compliant as possible. The fact that the high-aspect-ratio section of the device is embedded in the substrate enables the monolithic integration of high-aspect-ratio parts with surface-micromachined mechanical parts, and, in the future, also electronics. We anticipate that such an integrated mold/surface micromachining/electronics process will offer versatile high-aspect-ratio micromachined structures that can be batch-fabricated and monolithically integrated into complex microelectromechanical systems.

  17. Stable surface passivation process for compound semiconductors

    DOEpatents

    Ashby, Carol I. H.

    2001-01-01

    A passivation process for a previously sulfided, selenided or tellurated III-V compound semiconductor surface. The concentration of undesired mid-gap surface states on a compound semiconductor surface is reduced by the formation of a near-monolayer of metal-(sulfur and/or selenium and/or tellurium)-semiconductor that is effective for long term passivation of the underlying semiconductor surface. Starting with the III-V compound semiconductor surface, any oxidation present thereon is substantially removed and the surface is then treated with sulfur, selenium or tellurium to form a near-monolayer of chalcogen-semiconductor of the surface in an oxygen-free atmosphere. This chalcogenated surface is then contacted with a solution of a metal that will form a low solubility chalcogenide to form a near-monolayer of metal-chalcogen-semiconductor. The resulting passivating layer provides long term protection for the underlying surface at or above the level achieved by a freshly chalcogenated compound semiconductor surface in an oxygen free atmosphere.

  18. Changes of the surface structure of corn stalk in the cooking process with active oxygen and MgO-based solid alkali as a pretreatment of its biomass conversion.

    PubMed

    Pang, Chunsheng; Xie, Tujun; Lin, Lu; Zhuang, Junping; Liu, Ying; Shi, Jianbin; Yang, Qiulin

    2012-01-01

    This study presents a novel, efficient and environmentally friendly process for the cooking of corn stalk that uses active oxygen (O2 and H2O2) and a recoverable solid alkali (MgO). The structural changes on the surface of corn stalk before and after cooking were characterized by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) techniques. The results showed that lignin and extractives were effectively removed, especially those on the surface of corn stalk. Additionally, the changes included becoming fibrillar, the exposure of cellulose and hemi-cellulose and the pitting corrosion on the surface, etc. The results also showed that the removal reaction is from outside to inside, but the main reaction is possibly on the surface. Furthermore, the results of active oxygen cooking with a solid alkali are compared with those of alkaline cooking in the paper.

  19. Molecular Dynamics Simulations of Surface Processes: Oxygen Recombination on Silica Surfaces at High Temperature

    DTIC Science & Technology

    2007-07-01

    size-scalable cluster approach with SixOy clusters of increasing size cleaved from the β- cristobalite unit cell. In this study the hybrid Hartree...values of the β- cristobalite cell and extending the Molecular Dynamics Simulations of Surface Processes: Oxygen Recombination on Silica Surfaces at... cristobalite surface is reported as a function of the distance of the N atom from the Si active atom. The dashed line shows the interaction

  20. Land surface processes and Sahel climate

    NASA Astrophysics Data System (ADS)

    Nicholson, Sharon

    2000-02-01

    This paper examines the question of land surface-atmosphere interactions in the West African Sahel and their role in the interannual variability of rainfall. In the Sahel, mean rainfall decreased by 25-40% between 1931-1960 and 1968-1997; every year in the 1950s was wet, and nearly every year since 1970 has been anomalously dry. Thus the intensity and multiyear persistence of drought conditions are unusual and perhaps unique features of Sahel climate. This article presents arguments for the role of land surface feedback in producing these features and reviews research relevant to land surface processes in the region, such as results from the 1992 Hydrologic Atmospheric Pilot Experiment (HAPEX)-Sahel experiment and recent studies on aerosols and on the issue of desertification in the region, a factor implicated by some as a cause of the changes in rainfall. Included also is a summary of evidence of feedback on meteorological processes, presented from both model results and observations. The reviewed studies demonstrate numerous ways in which the state of the land surface can influence interactions with the atmosphere. Surface hydrology essentially acts to delay and prolong the effects of meteorological drought. Each evaporative component of the surface water balance has its own timescale, with the presence of vegetation affecting the process both by delaying and prolonging the return of soil moisture to the atmosphere but at the same time accelerating the process through the evaporation of canopy-intercepted water. Hence the vegetation structure, including rooting depth, can modulate the land-atmosphere interaction. Such processes take on particular significance in the Sahel, where there is a high degree of recycling of atmospheric moisture and where the meteorological processes from the scale of boundary layer development to mesoscale disturbance generation are strongly influenced by moisture. Simple models of these feedback processes and their various timescales

  1. Mineralogy of the Martian Surface: Crustal Composition to Surface Processes

    NASA Technical Reports Server (NTRS)

    Mustard, John F.

    1997-01-01

    The main results have been published in the refereed literature, and thus this report serves mainly to summarize the main findings and indicate where the detailed papers may be found. Reflectance spectroscopy has been an important tool for determining the mineralogic makeup of the near surface materials on Mars. Analysis of the spectral properties of the surface have demonstrated that these attributes are heterogeneous from the coarse spatial but high spectral resolution spectra obtained with telescopes to the high spatial but coarse spectral resolution Viking data (e.g. Arvidson et al., 1989; McEwen et al., 1989). Low albedo materials show strong evidence for the presence of igneous rock forming minerals while bright materials are generally interpreted as representing heavily altered crustal material. How these materials are physically and genetically related has important implications for understanding martian surface properties and processes, weathering histories and paths, and crustal composition. The goal of this research is to characterize the physical and chemical properties of low albedo materials on Mars and the relationship to intermediate and high albedo materials. Fundamental science questions to be pursued include: (1) the observed distributions of soil, rock, and dust a function of physical processes or weathering and (2) different stages of chemical and physical alteration fresh rock identified. These objectives will be addressed through detailed analyses and modelling of the ISM data from the Phobos-2 mission with corroborating evidence of surface composition and properties provided by data from the Viking mission.

  2. Advanced oxidation process sanitization of eggshell surfaces.

    PubMed

    Gottselig, Steven M; Dunn-Horrocks, Sadie L; Woodring, Kristy S; Coufal, Craig D; Duong, Tri

    2016-06-01

    The microbial quality of eggs entering the hatchery represents an important critical control point for biosecurity and pathogen reduction programs in integrated poultry production. The development of safe and effective interventions to reduce microbial contamination on the surface of eggs will be important to improve the overall productivity and microbial food safety of poultry and poultry products. The hydrogen peroxide (H2O2) and ultraviolet (UV) light advanced oxidation process is a potentially important alternative to traditional sanitizers and disinfectants for egg sanitation. The H2O2/UV advanced oxidation process was demonstrated previously to be effective in reducing surface microbial contamination on eggs. In this study, we evaluated treatment conditions affecting the efficacy of H2O2/UV advanced oxidation in order to identify operational parameters for the practical application of this technology in egg sanitation. The effect of the number of application cycles, UV intensity, duration of UV exposure, and egg rotation on the recovery of total aerobic bacteria from the surface of eggs was evaluated. Of the conditions evaluated, we determined that reduction of total aerobic bacteria from naturally contaminated eggs was optimized when eggs were sanitized using 2 repeated application cycles with 5 s exposure to 14 mW cm(-2) UV light, and that rotation of the eggs between application cycles was unnecessary. Additionally, using these optimized conditions, the H2O2/UV process reduced Salmonella by greater than 5 log10 cfu egg(-1) on the surface of experimentally contaminated eggs. This study demonstrates the potential for practical application of the H2O2/UV advanced oxidation process in egg sanitation and its effectiveness in reducing Salmonella on eggshell surfaces.

  3. Thermal microactuators for surface-micromachining processes

    NASA Astrophysics Data System (ADS)

    Comtois, John H.; Bright, Victor M.; Phipps, Mark W.

    1995-09-01

    Microelectromechanical systems must include large-deflection actuators to create devices which can interact mechanically with their surroundings. Electrostatic actuators with large nonresonant motion require high voltages and large surface areas to produce useful forces. Large-deflection thermal actuators have been fabricated in electroplated metal processes, but the choice of materials is limited, and the high conductivity of metal means these devices need a high current to generate the required heat. Thus, there is a need for a low voltage actuator with a large nonresonant deflection which can be fabricated in integrated circuit compatible surface-micromachining processes. The device described in this paper has a simple, flexible, and reliable design which overcomes the limitations of other actuators. It is a low voltage, medium current thermal actuator which can be designed to move laterally in a controllable, nonresonant motion. Typical actuators are 200 micrometers long, 18 micrometers wide, and deflect 10 micrometers at the tip with a drive current of 5 mA at 5 volts. A wide range of layout geometries allows this type of actuator to be fabricated in any surface-micromachining process that includes a releasable, current-carrying layer. An empirical model is presented to describe the devices fabricate in a commercially available surface-micromachining process. Arrays of actuators were fabricated to test the effect of different device dimensions on maximum achievable deflection as a funciton of applied current. Actuators can be combined to produce more force and have been integrated with other micromechanical structures. Applications of these actuators include linear and rotating motors, compliant micromechanisms, latches, micro-relays, variable capacitators and tweezers.

  4. ENVISAT Land Surface Processes. Phase 2

    NASA Technical Reports Server (NTRS)

    vandenHurk, B. J. J. M.; Su, Z.; Verhoef, W.; Menenti, M.; Li, Z.-L.; Wan, Z.; Moene, A. F.; Roerink, G.; Jia, I.

    2002-01-01

    This is a progress report of the 2nd phase of the project ENVISAT- Land Surface Processes, which has a 3-year scope. In this project, preparative research is carried out aiming at the retrieval of land surface characteristics from the ENVISAT sensors MERIS and AATSR, for assimilation into a system for Numerical Weather Prediction (NWP). Where in the 1st phase a number of first shot experiments were carried out (aiming at gaining experience with the retrievals and data assimilation procedures), the current 2nd phase has put more emphasis on the assessment and improvement of the quality of the retrieved products. The forthcoming phase will be devoted mainly to the data assimilation experiments and the assessment of the added value of the future ENVISAT products for NWP forecast skill. Referring to the retrieval of albedo, leaf area index and atmospheric corrections, preliminary radiative transfer calculations have been carried out that should enable the retrieval of these parameters once AATSR and MERIS data become available. However, much of this work is still to be carried out. An essential part of work in this area is the design and implementation of software that enables an efficient use of MODTRAN(sub 4) radiative transfer code, and during the current project phase familiarization with these new components has been achieved. Significant progress has been made with the retrieval of component temperatures from directional ATSR-images, and the calculation of surface turbulent heat fluxes from these data. The impact of vegetation cover on the retrieved component temperatures appears manageable, and preliminary comparison of foliage temperature to air temperatures were encouraging. The calculation of surface fluxes using the SEBI concept,which includes a detailed model of the surface roughness ratio, appeared to give results that were in reasonable agreement with local measurements with scintillometer devices. The specification of the atmospheric boundary conditions

  5. Enceladus and Tethys: Ultraviolet clues to surface composition & surface processing

    NASA Astrophysics Data System (ADS)

    Hendrix, Amanda R.; Hansen, Candice; Cassidy, Timothy A.; Royer, Emilie M.; Esposito, Larry W.; Holsclaw, Gregory

    2016-10-01

    Cassini's Ultraviolet Imaging Spectrograph (UVIS) is sensitive to the uppermost portion of the regoliths of the icy Saturnian moons, where interactions with E-ring grains and plasma processing are important. Organics are present in at least 30% of E ring grains (Postberg et al., 2008) and are likely transported to the surfaces of the satellites orbiting Saturn within the E ring. Plasma bombardment on the trailing hemispheres of the satellites can further process these organic species. Enceladus' surface exhibits visible color variations (Schenk et al., 2011), evidence of plume fall-out zones and zones where plume fall-out is not as heavy (and where E ring grain bombardment dominates). In this study, we investigate far-UV spectral and photometric differences in the Enceladus plume fallout and non-fallout regions to study compositional and structural differences, and we also study compositional and photometric variations in regions on Tethys' trailing and leading hemispheres to understand spectral effects of organics, E ring bombardment and plasma bombardment.

  6. Directional emittance surface measurement system and process

    NASA Technical Reports Server (NTRS)

    Puram, Chith K. (Inventor); Daryabeigi, Kamran (Inventor); Wright, Robert (Inventor); Alderfer, David W. (Inventor)

    1994-01-01

    Apparatus and process for measuring the variation of directional emittance of surfaces at various temperatures using a radiometric infrared imaging system. A surface test sample is coated onto a copper target plate provided with selective heating within the desired incremental temperature range to be tested and positioned onto a precision rotator to present selected inclination angles of the sample relative to the fixed positioned and optically aligned infrared imager. A thermal insulator holder maintains the target plate on the precision rotator. A screen display of the temperature obtained by the infrared imager, and inclination readings are provided with computer calculations of directional emittance being performed automatically according to equations provided to convert selected incremental target temperatures and inclination angles to relative target directional emittance values. The directional emittance of flat black lacquer and an epoxy resin measurements obtained are in agreement with the predictions of the electromagnetic theory and with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

  7. Surface-active materials from Athabasca oil sands

    NASA Astrophysics Data System (ADS)

    Moschopedis, S. E.; Schulz, K. F.; Speight, J. G.; Morrison, D. N.

    1980-01-01

    Surface-active derivatives can be separated, or chemically-derived, from Athabasca bitumen. These materials have the ability to lower the surface tensions of aqueous solutions as well as substantially reduce the interfacial tensions of aqueous-organic systems. As such, they do appear to have a beneficial effect on bitumen recovery processes.

  8. Uncovering deformation processes from surface displacements

    NASA Astrophysics Data System (ADS)

    Stramondo, Salvatore; Trasatti, Elisa; Albano, Matteo; Moro, Marco; Chini, Marco; Bignami, Christian; Polcari, Marco; Saroli, Michele

    2016-12-01

    Today, satellite remote sensing has reached a key role in Earth Sciences. In particular, Synthetic Aperture Radar (SAR) sensors and SAR Interferometry (InSAR) techniques are widely used for the study of dynamic processes occurring inside our living planet. Over the past 3 decades, InSAR has been applied for mapping topography and deformation at the Earth's surface. These maps are widely used in tectonics, seismology, geomorphology, and volcanology, in order to investigate the kinematics and dynamics of crustal faulting, the causes of postseismic and interseismic displacements, the dynamics of gravity driven slope failures, and the deformation associated with subsurface movement of water, hydrocarbons or magmatic fluids.

  9. Active Inference: A Process Theory.

    PubMed

    Friston, Karl; FitzGerald, Thomas; Rigoli, Francesco; Schwartenbeck, Philipp; Pezzulo, Giovanni

    2017-01-01

    This article describes a process theory based on active inference and belief propagation. Starting from the premise that all neuronal processing (and action selection) can be explained by maximizing Bayesian model evidence-or minimizing variational free energy-we ask whether neuronal responses can be described as a gradient descent on variational free energy. Using a standard (Markov decision process) generative model, we derive the neuronal dynamics implicit in this description and reproduce a remarkable range of well-characterized neuronal phenomena. These include repetition suppression, mismatch negativity, violation responses, place-cell activity, phase precession, theta sequences, theta-gamma coupling, evidence accumulation, race-to-bound dynamics, and transfer of dopamine responses. Furthermore, the (approximately Bayes' optimal) behavior prescribed by these dynamics has a degree of face validity, providing a formal explanation for reward seeking, context learning, and epistemic foraging. Technically, the fact that a gradient descent appears to be a valid description of neuronal activity means that variational free energy is a Lyapunov function for neuronal dynamics, which therefore conform to Hamilton's principle of least action.

  10. Does Titan have an Active Surface?

    NASA Astrophysics Data System (ADS)

    Nelson, R.

    2009-12-01

    ammonia, a compound expected in Titan’s interior. This, combined with the previous evidence from VIMS and RADAR images, creates a strong case for Titan having a presently active surface, possibly due to cryovolcanism. Cassini encountered Titan at very close range on 2008-11-19-13:58 and again on 2008-12-05-12:38. These epochs are called T47 and T48. Comparison of earlier lower resolution data (T5) with the recent T47 and T48 data reveal changes of the surface reflectance and morphology in the Hotei region. This is the first evidence from VIMS that confirms the RADAR report that Hotei Reggio has morphology consistent with volcanic terrain. It has not escaped our attention that ammonia, in association with methane and nitrogen, the principal species of Titan’s atmosphere, closely replicates the environment at the time that live first emerged on earth. If Titan is currently active then these results raise the following questions: What is the full extent of current geologic activity? What are the ongoing processes? Are Titan’s chemical processes today supporting a prebiotic chemistry similar to that under which life evolved on Earth? This work done at JPL under contract with NASA. Refs: [1]R. M. Nelson et al., Icarus 199 (2009) 429-441. [2]R. M. Nelson et al., GRL, VOL. 36, L04202, doi:10.1029/2008GL036206, 2009. [3]S. D. Wall GRL, VOL. 36, L04203, doi:10.1029/2008GL036415, 2009

  11. Surface modification of active material structures in battery electrodes

    DOEpatents

    Erickson, Michael; Tikhonov, Konstantin

    2016-02-02

    Provided herein are methods of processing electrode active material structures for use in electrochemical cells or, more specifically, methods of forming surface layers on these structures. The structures are combined with a liquid to form a mixture. The mixture includes a surface reagent that chemically reacts and forms a surface layer covalently bound to the structures. The surface reagent may be a part of the initial liquid or added to the mixture after the liquid is combined with the structures. In some embodiments, the mixture may be processed to form a powder containing the structures with the surface layer thereon. Alternatively, the mixture may be deposited onto a current collecting substrate and dried to form an electrode layer. Furthermore, the liquid may be an electrolyte containing the surface reagent and a salt. The liquid soaks the previously arranged electrodes in order to contact the structures with the surface reagent.

  12. Immobilization of Active Bacteriophages on Polyhydroxyalkanoate Surfaces.

    PubMed

    Wang, Chanchan; Sauvageau, Dominic; Elias, Anastasia

    2016-01-20

    A rapid, efficient technique for the attachment of bacteriophages (phages) onto polyhydroxyalkanoate (PHA) surfaces has been developed and compared to three reported methods for phage immobilization. Polymer surfaces were modified to facilitate phage attachment using (1) plasma treatment alone, (2) plasma treatment followed by activation by 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (sulfo-NHS), (3) plasma-initiated acrylic acid grafting, or (4) plasma-initiated acrylic acid grafting with activation by EDC and sulfo-NHS. The impact of each method on the surface chemistry of PHA was investigated using contact angle analysis and X-ray photoelectron spectroscopy. Each of the four treatments was shown to result in both increased hydrophilicity and in the modification of the surface functional groups. Modified surfaces were immersed in suspensions of phage T4 for immobilization. The highest level of phage binding was observed for the surfaces modified by plasma treatment alone. The change in chemical bond states observed for surfaces that underwent plasma treatment is suspected to be the cause of the increased binding of active phages. Plasma-treated surfaces were further analyzed through phage-staining and fluorescence microscopy to assess the surface density of immobilized phages and their capacity to capture hosts. The infective capability of attached phages was confirmed by exposing the phage-immobilized surfaces to the host bacteria Escherichia coli in both plaque and infection dynamic assays. Plasma-treated surfaces with immobilized phages displayed higher infectivity than surfaces treated with other methods; in fact, the equivalent initial multiplicity of infection was 2 orders of magnitude greater than with other methods. Control samples - prepared by immersing polymer surfaces in phage suspensions (without prior plasma treatment) - did not show any bacterial growth inhibition, suggesting they did not bind

  13. Impact of Urban Surfaces on Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Shepherd, J. M.

    2004-01-01

    The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess the "risk of human-induced climate change". Such reports are used by decision-makers around the world to assess how our climate is changing. Its reports are widely respected and cited and have been highly influential in forming national and international responses to climate change. The Fourth Assessment report includes a section on the effects of surface processes on climate. This sub-chapter provides an overview of recent developments related to the impact of cities on rainfall. It highlights the possible mechanisms that buildings, urban heat islands, urban aerosols or pollution, and other human factors in cities that can affect rainfall.

  14. Surface magnetization processes in soft magnetic nanowires

    NASA Astrophysics Data System (ADS)

    Lupu, N.; Lostun, M.; Chiriac, H.

    2010-05-01

    The surface magnetization processes taking place in simple permalloy (Py) and FeGa nanowires, Py/Cu, CoFeB/Cu, CoNiP/Cu, FeGa/Py, and FeGa/CoFeB multilayered nanowires have been studied by magneto-optical Kerr effect (MOKE) magnetometry. The results indicate a strong correlation between the direction of the anisotropy axis relative to the direction of the applied field and the plane of incidence of the laser spot, as well as the effect of dipolar interactions between the nanowires or between the ferromagnetic layers on the magnetization reversal. The larger laser spots are inducing more noise in the MOKE hysteresis loops because of the dimensional imperfections along the nanowires.

  15. Uncovering deformation processes from surface displacements

    NASA Astrophysics Data System (ADS)

    Stramondo, Salvatore

    2013-04-01

    The aim of this talk is to provide an overview about the most recent outcomes in Earth Sciences, describe the role of satellite remote sensing, together with GPS, ground measurement and further data, for geophysical parameter retrieval in well known case studies where the combined approach dealing with the use of two or more techniques/datasets have demonstrated their effectiveness. The Earth Sciences have today a wide availability of instruments and sensors able to provide scientists with an unprecedented capability to study the physical processes driving earthquakes, volcanic eruptions, landslides, and other dynamic Earth systems. Indeed measurements from satellites allow systematic observation of the Earth surface covering large areas, over a long time period and characterized by growing sample intervals. Interferometric Synthetic Aperture Radar (InSAR) technique has demonstrated its effectiveness to investigate processes responsible for crustal faulting stemming from the detection of surface deformation patterns. Indeed using satellite data along ascending and descending orbits, as well as different incident angles, it is possible in principle to retrieve the full 3D character of the ground motion. To such aim the use of GPS stations providing 3D displacement components is a reliable complementary instrument. Finally, offset tracking techniques and Multiple Aperture Interferometry (MAI) may provide a contribution to the analysis of horizontal and NS deformation vectors. The estimation of geophysical parameters using InSAR has been widely discussed in seismology and volcanology, and also applied to deformation associated with groundwater and other subsurface fluids. These applications often involve the solution of an inverse problem, which means the retrieval of optimal source parameters at depth for volcanoes and earthquakes, from the knowledge of surface deformation from InSAR. In recent years, InSAR measurements combined with traditional seismological and

  16. Regional scale hydrology with a new land surface processes model

    NASA Technical Reports Server (NTRS)

    Laymon, Charles; Crosson, William

    1995-01-01

    Through the CaPE Hydrometeorology Project, we have developed an understanding of some of the unique data quality issues involved in assimilating data of disparate types for regional-scale hydrologic modeling within a GIS framework. Among others, the issues addressed here include the development of adequate validation of the surface water budget, implementation of the STATSGO soil data set, and implementation of a remote sensing-derived landcover data set to account for surface heterogeneity. A model of land surface processes has been developed and used in studies of the sensitivity of surface fluxes and runoff to soil and landcover characterization. Results of these experiments have raised many questions about how to treat the scale-dependence of land surface-atmosphere interactions on spatial and temporal variability. In light of these questions, additional modifications are being considered for the Marshall Land Surface Processes Model. It is anticipated that these techniques can be tested and applied in conjunction with GCIP activities over regional scales.

  17. Active micromixer using surface acoustic wave streaming

    SciTech Connect

    Branch; Darren W. , Meyer; Grant D. , Craighead; Harold G.

    2011-05-17

    An active micromixer uses a surface acoustic wave, preferably a Rayleigh wave, propagating on a piezoelectric substrate to induce acoustic streaming in a fluid in a microfluidic channel. The surface acoustic wave can be generated by applying an RF excitation signal to at least one interdigital transducer on the piezoelectric substrate. The active micromixer can rapidly mix quiescent fluids or laminar streams in low Reynolds number flows. The active micromixer has no moving parts (other than the SAW transducer) and is, therefore, more reliable, less damaging to sensitive fluids, and less susceptible to fouling and channel clogging than other types of active and passive micromixers. The active micromixer is adaptable to a wide range of geometries, can be easily fabricated, and can be integrated in a microfluidic system, reducing dead volume. Finally, the active micromixer has on-demand on/off mixing capability and can be operated at low power.

  18. Photochemical Transformation Processes in Sunlit Surface Waters

    NASA Astrophysics Data System (ADS)

    Vione, D.

    2012-12-01

    Photochemical reactions are major processes in the transformation of hardly biodegradable xenobiotics in surface waters. They are usually classified into direct photolysis and indirect or sensitised degradation. Direct photolysis requires xenobiotic compounds to absorb sunlight, and to get transformed as a consequence. Sensitised transformation involves reaction with transient species (e.g. °OH, CO3-°, 1O2 and triplet states of chromophoric dissolved organic matter, 3CDOM*), photogenerated by so-called photosensitisers (nitrate, nitrite and CDOM). CDOM is a major photosensitiser: is it on average the main source of °OH (and of CO3-° as a consequence, which is mainly produced upon oxidation by °OH of carbonate and bicarbonate) and the only important source of 1O2 and 3CDOM* [1, 2]. CDOM origin plays a key role in sensitised processes: allochthonous CDOM derived from soil runoff and rich in fulvic and humic substances is usually more photoactive than autochthonous CDOM (produced by in-water biological processes and mainly consisting of protein-like material) or of CDOM derived from atmospheric deposition. An interesting gradual evolution of CDOM origin and photochemistry can be found in mountain lakes across the treeline, which afford a gradual transition of allochthonous- autochtonous - atmopheric CDOM when passing from trees to alpine meadows to exposed rocks [3]. Another important issue is the sites of reactive species photoproduction in CDOM. While there is evidence that smaller molecular weight fractions are more photoactive, some studies have reported considerable 1O2 reactivity in CDOM hydrophobic sites and inside particles [4]. We have recently addressed the problem and found that dissolved species in standard humic acids (hydrodynamic diameter < 0.1 μm) account for the vast majority of 1O2 and triplet states photoproduction. In hydrophobic sites of particles, the formation rate of 1O2 is considerably lower than in the solution bulk [5], but the absence

  19. Asphaltene surface activity at oil/water interfaces

    SciTech Connect

    Sheu, E.Y.; Shields, M.B.

    1995-11-01

    Small angle neutron scattering (SANS) dynamic surface tension (DST), dynamic interfacial tension (DIFT), and zero shear viscosity were used to study the surface activity of Ratawi asphaltenes in organic solvents, in the asphaltene/water/toluene emulsions and at the toluene/aqueous solution interfaces. In organic solvents, the kinetic process of micellization and the micellar structure are characterized. Their dependence on asphaltene concentration was investigated. The emulsion droplet structure and their capability in water uptake was tested. Also, the enhancement of surface activity of asphaltenes and its potential applications are briefly discussed.

  20. Process for hardening the surface of polymers

    DOEpatents

    Mansur, L.K.; Lee, E.H.

    1992-07-14

    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance. 1 figure.

  1. Process for hardening the surface of polymers

    DOEpatents

    Mansur, Louis K.; Lee, Eal H.

    1992-01-01

    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance.

  2. Active Flow Control Stator With Coanda Surface

    NASA Technical Reports Server (NTRS)

    Guendogdu; Vorreiter; Seume

    2010-01-01

    Active Flow Control increases the permissible aerodynamic loading. Curved surface near the trailing edge ("Coanda surface"): a) increases turning -> higher pressure ratio. b) controls boundary layer separation -> increased surge margin. Objective: Reduce the number of vanes or compressor stages. Constraints: 1. In a real compressor, the vane must still function entirely without blowing. 2. Maintain the flow exit angle of the reference stator despite the resulting increase in stator loading.

  3. Space environment and lunar surface processes

    NASA Technical Reports Server (NTRS)

    Comstock, G. M.

    1979-01-01

    The development of a general rock/soil model capable of simulating in a self consistent manner the mechanical and exposure history of an assemblage of solid and loose material from submicron to planetary size scales, applicable to lunar and other space exposed planetary surfaces is discussed. The model was incorporated into a computer code called MESS.2 (model for the evolution of space exposed surfaces). MESS.2, which represents a considerable increase in sophistication and scope over previous soil and rock surface models, is described. The capabilities of previous models for near surface soil and rock surfaces are compared with the rock/soil model, MESS.2.

  4. Optical Activity of Anisotropic Achiral Surfaces

    SciTech Connect

    Verbiest, T.; Kauranen, M.; Van Rompaey, Y.; Persoons, A. |

    1996-08-01

    Anisotropic achiral surfaces respond differently to left- and right-hand circularly polarized light. This occurs when the orientation of the surface with respect to an otherwise achiral experimental setup makes the total geometry chiral. Such optical activity is demonstrated in second-harmonic generation from an anisotropic thin molecular film. The circular-difference response reverses sign as the handedness of the geometry is reversed and vanishes when the setup possesses a mirror plane. The results are explained within the electric-dipole-allowed second-order surface nonlinearity. {copyright} {ital 1996 The American Physical Society.}

  5. Active Surfaces and Interfaces of Soft Materials

    NASA Astrophysics Data System (ADS)

    Wang, Qiming

    A variety of intriguing surface patterns have been observed on developing natural systems, ranging from corrugated surface of white blood cells at nanometer scales to wrinkled dog skins at millimeter scales. To mimetically harness functionalities of natural morphologies, artificial transformative skin systems by using soft active materials have been rationally designed to generate versatile patterns for a variety of engineering applications. The study of the mechanics and design of these dynamic surface patterns on soft active materials are both physically interesting and technologically important. This dissertation starts with studying abundant surface patterns in Nature by constructing a unified phase diagram of surface instabilities on soft materials with minimum numbers of physical parameters. Guided by this integrated phase diagram, an electroactive system is designed to investigate a variety of electrically-induced surface instabilities of elastomers, including electro-creasing, electro-cratering, electro-wrinkling and electro-cavitation. Combing experimental, theoretical and computational methods, the initiation, evolution and transition of these instabilities are analyzed. To apply these dynamic surface instabilities to serving engineering and biology, new techniques of Dynamic Electrostatic Lithography and electroactive anti-biofouling are demonstrated.

  6. Automated Process Initialization of Laser Surface Structuring Processes by Inline Process Metrology

    NASA Astrophysics Data System (ADS)

    Schmitt, R.; Mallmann, G.; Winands, K.; Pothen, M.

    Laser micro machining as well as laser surface structuring are innovative manufacturing technologies with a wide range of machinable materials and a high level of flexibility. These techniques are characterized by different machine, workpiece and environmental parameters. The large amount of process dependencies lead however to a time consuming process initialization and a complex process control. Currently no automated solution exists to achieve material specific process parameters, nor does a sufficient inline process control exist to adapt processing parameters or strategies inline. Therefore a novel scanner based inline metrology solution and an automated process initialization strategy has been developed.

  7. Parallel Activation in Bilingual Phonological Processing

    ERIC Educational Resources Information Center

    Lee, Su-Yeon

    2011-01-01

    In bilingual language processing, the parallel activation hypothesis suggests that bilinguals activate their two languages simultaneously during language processing. Support for the parallel activation mainly comes from studies of lexical (word-form) processing, with relatively less attention to phonological (sound) processing. According to…

  8. Excimer laser surface modification: Process and properties

    SciTech Connect

    Jervis, T.R.; Nastasi, M.; Hirvonen, J.P.

    1992-12-01

    Surface modification can improve materials for structural, tribological, and corrosion applications. Excimer laser light has been shown to provide a rapid means of modifying surfaces through heat treating, surface zone refining, and mixing. Laser pulses at modest power levels can easily melt the surfaces of many materials. Mixing within the molten layer or with the gas ambient may occur, if thermodynamically allowed, followed by rapid solidification. The high temperatures allow the system to overcome kinetic barriers found in some ion mixing experiments. Alternatively, surface zone refinement may result from repeated melting-solidification cycles. Ultraviolet laser light couples energy efficiently to the surface of metallic and ceramic materials. The nature of the modification that follows depends on the properties of the surface and substrate materials. Alloying from both gas and predeposited layer sources has been observed in metals, semiconductors, and ceramics as has surface enrichment of Cr by zone refinement of stainless steel. Rapid solidification after melting often results in the formation of nonequilibrium phases, including amorphous materials. Improved surface properties, including tribology and corrosion resistance, are observed in these materials.

  9. Surface Chemistry in Electrochemical Atomic Layer Processing

    DTIC Science & Technology

    2007-11-02

    example, where a thin film of a material is formed an atomic layer at a time. That is, surface limited reactions are used to deposit individual atomic...The present studies were designed to investigate these surface limited reactions. To determine what the structures of the deposits were, and how that structure influenced subsequent deposition .

  10. Measurement of heterogeneous chemical processes relevant to aerosol surfaces and trace gases active in the marine environment. Progress report, February 1994--January 1995

    SciTech Connect

    Davidovits, P.; Worsnop, D.R.; Zahniser, M.S.; Jayne, J.T.; Kolb, C.E.

    1995-02-01

    Biogenically produced reduced sulfur compounds from the marine environment, deliver a sulfur burden to the atmosphere which is about half as large as that due to sulfur oxides produced by fossil fuel combustion. The multiphase chemical processes for these species must be understood in order to evaluate the relative roles of biogenic and combustion produced sulfur oxides over the oceans. The aim of the studies funded by the subject DOE grant is to measure parameters governing the heterogeneous chemistry of the species occurring in the marine environment. During the past year, uptake studies for the sulfur species MSA, DMSO, DMSO{sub 2}, DMS, OCS, CS{sub 2}, H{sub 2}S, and CH{sub 3}SH have been finalized. Studies of the reactive uptake of Cl{sub 2} and Br{sub 2} by Br{sup -} and I{sup -} solutions as a function of temperature have been completed. The uptake of O{sub 3} by aqueous NaI solutions has also been studied for the purpose of comparison. We have begun co-deposition studies and have obtained some preliminary results for the codeposition with ozone of DMS, DMSO, DMSO{sub 2} and MSA. For the next phase of the work, a new horizontal bubbler apparatus was designed and built and construction to improve the detection sensitivity of the apparatuses was begun. Altogether during 1994, 8 articles have been accepted for publication and 2 Ph.D. dissertations have been submitted and approved.

  11. Active Acetylcholinesterase Immobilization on a Functionalized Silicon Surface.

    PubMed

    Khaldi, K; Sam, S; Gouget-Laemmel, A C; Henry de Villeneuve, C; Moraillon, A; Ozanam, F; Yang, J; Kermad, A; Ghellai, N; Gabouze, N

    2015-08-04

    In this work, we studied the attachment of active acetylcholinesterase (AChE) enzyme on a silicon substrate as a potential biomarker for the detection of organophosphorous (OP) pesticides. A multistep functionalization strategy was developed on a crystalline silicon surface: a carboxylic acid-terminated monolayer was grafted onto a hydrogen-terminated silicon surface by photochemical hydrosilylation, and then AChE was covalently attached through amide bonds using an activation EDC/NHS process. Each step of the modification was quantitatively characterized by ex-situ Fourier transform infrared spectroscopy in attenuated-total-reflection geometry (ATR-FTIR) and atomic force microscopy (AFM). The kinetics of enzyme immobilization was investigated using in situ real-time infrared spectroscopy. The enzymatic activity of immobilized acetylcholinesterase enzymes was determined with a colorimetric test. The surface concentration of active AChE was estimated to be Γ = 1.72 × 10(10) cm(-2).

  12. Intrepretation of surface features and surface processes on Mars

    NASA Technical Reports Server (NTRS)

    Gad-El-hak, M.; Howard, A.; Morton, J. B.; Pierce, D.

    1975-01-01

    Eolian erosion and deposition on earth was studied in order to interpret the eolian land forms of Mars. Emphasis of the wind tunnel studies was on the flow field around models of eolian forms. Areas of the wind tunnel studies include: simulation of the atmospheric boundary layer; velocity profile measurements around different models in the desert boundary layer, and estimating shear stress distributions on the model surfaces; flow visualization techniques; streamline mapping using tuft photographs; and roughness contrasts.

  13. Mechanotransductive surfaces for reversible biocatalysis activation

    NASA Astrophysics Data System (ADS)

    Mertz, Damien; Vogt, Cédric; Hemmerlé, Joseph; Mutterer, Jérôme; Ball, Vincent; Voegel, Jean-Claude; Schaaf, Pierre; Lavalle, Philippe

    2009-09-01

    Fibronectin, like other proteins involved in mechanotransduction, has the ability to exhibit recognition sites under mechanical stretch. Such cryptic sites are buried inside the protein structure in the native fold and become exposed under an applied force, thereby activating specific signalling pathways. Here, we report the design of new active polymeric nanoassembled surfaces that show some similarities to these cryptic sites. These nanoassemblies consist of a first polyelectrolyte multilayer stratum loaded with enzymes and capped with a second polyelectrolyte multilayer acting as a mechanically sensitive nanobarrier. The biocatalytic activity of the film is switched on/off reversibly by mechanical stretching, which exposes enzymes through the capping barrier, similarly to mechanisms involved in proteins during mechanotransduction. This first example of a new class of biologically inspired surfaces should have great potential in the design of various devices aimed to trigger and modulate chemical reactions by mechanical action with applications in the field of microfluidic devices or mechanically controlled biopatches for example.

  14. Volatile processes in Triton's atmosphere and surface

    NASA Technical Reports Server (NTRS)

    Lunine, J. I.

    1992-01-01

    A basic model for latitudinal transport of nitrogen is reviewed focusing on its limitations and some complications associated with surface and atmospheric physics. Data obtained by 1989 Voyager encounter with the Neptune system revealed the complexity in the pure nitrogen transport which is caused by the nonuniform albedo of the frosts. It is concluded that Triton is similar to Mars in terms of the complexity of volatile transport and to understand Triton's surface-atmosphere system, Mars may be a very good analog.

  15. Dual Active Surface Heat Flux Gage Probe

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.; Kolodziej, Paul

    1995-01-01

    A unique plug-type heat flux gage probe was tested in the NASA Ames Research Center 2x9 turbulent flow duct facility. The probe was fabricated by welding a miniature dual active surface heat flux gage body to the end of a hollow metal cylindrical bolt containing a metal inner tube. Cooling air flows through the inner tube, impinges onto the back of the gage body and then flows out through the annulus formed between the inner tube and the hollow bolt wall. Heat flux was generated in the duct facility with a Huels arc heater. The duct had a rectangular cross section and one wall was fabricated from 2.54 centimeter thick thermal insulation rigid surface material mounted onto an aluminum plate. To measure heat flux, the probe was inserted through the plate and insulating materials with the from of the gage located flush with the hot gas-side insulation surface. Absorbed heat fluxes measured with the probe were compared with absorbed heat fluxes measured with six water-cooled reference calorimeters. These calorimeters were located in a water-cooled metal duct wall which was located across from the probe position. Correspondence of transient and steady heat fluxes measured with the reference calorimeters and heat flux gage probe was generally within a satisfactory plus or minus 10 percent. This good correspondence was achieved even though the much cooler probe caused a large surface temperature disruption of 1000K between the metal gage and the insulation. However, this temperature disruption did not seriously effect the accuracy of the heat flux measurement. A current application for dual active surface heat flux gages is for transient and steady absorbed heat flux, surface temperature and heat transfer coefficient measurements on the surface of an oxidizer turbine inlet deflector operating in a space shuttle test bed engine.

  16. Dual active surface heat flux gage probe

    NASA Astrophysics Data System (ADS)

    Liebert, Curt H.; Kolodziej, Paul

    1995-02-01

    A unique plug-type heat flux gage probe was tested in the NASA Ames Research Center 2x9 turbulent flow duct facility. The probe was fabricated by welding a miniature dual active surface heat flux gage body to the end of a hollow metal cylindrical bolt containing a metal inner tube. Cooling air flows through the inner tube, impinges onto the back of the gage body and then flows out through the annulus formed between the inner tube and the hollow bolt wall. Heat flux was generated in the duct facility with a Huels arc heater. The duct had a rectangular cross section and one wall was fabricated from 2.54 centimeter thick thermal insulation rigid surface material mounted onto an aluminum plate. To measure heat flux, the probe was inserted through the plate and insulating materials with the from of the gage located flush with the hot gas-side insulation surface. Absorbed heat fluxes measured with the probe were compared with absorbed heat fluxes measured with six water-cooled reference calorimeters. These calorimeters were located in a water-cooled metal duct wall which was located across from the probe position. Correspondence of transient and steady heat fluxes measured with the reference calorimeters and heat flux gage probe was generally within a satisfactory plus or minus 10 percent. This good correspondence was achieved even though the much cooler probe caused a large surface temperature disruption of 1000K between the metal gage and the insulation. However, this temperature disruption did not seriously effect the accuracy of the heat flux measurement. A current application for dual active surface heat flux gages is for transient and steady absorbed heat flux, surface temperature and heat transfer coefficient measurements on the surface of an oxidizer turbine inlet deflector operating in a space shuttle test bed engine.

  17. Wright Valley Sediments as Potential Analogs for Martian Surface Processes

    NASA Astrophysics Data System (ADS)

    Englert, P. A. J.; Bishop, J. L.; Patel, S.; Gibson, E. K.; Koeberl, C.

    2015-12-01

    The Antarctic Dry Valleys (ADV) may provide a unique terrestrial analog for current Martian surface processes. The Wright Valley located in the ADV contains streams, lakes and ponds that host highly saline, sedimentary environments. This project highlights comparisons of formation and salt accumulation processes at the Don Juan Pond (DJP) and Don Quixote Pond (DQP). These are located in the north and south forks of the Wright Valley, which are unique areas where unusual terrestrial processes can be studied. DQP is located in the western part of the north fork about 100 m above mean seawater level. The DQP Valley walls are up to 2500 m high and the brine is seasonally frozen. DJP from the south fork is located ~9 km west of Lake Vanda. The basin floor is 117 m above mean seawater level with activity to the north and south rising above 1000 m. The DJP brine does not freeze and may be a model environment for Ca and Cl weathering and distribution on Mars. Our findings indicate that DJP and DQP have formed in similar climatic and geological environments, but likely experienced different formation conditions. Samples were collected from surface, soil pits and depth profiles during the 1979/1980, the 1990/1991 and the 2005/2006 field seasons. Elemental abundances and mineralogy were evaluated for several sets of sediments. The DJP basin shows low surface abundances of halite and relatively high abundances of sulfates throughout with gypsum or anhydrite dominating at different locations. The DQP area has high surface abundances of halite with gypsum present as the major sulfate. Two models have been proposed to explain these differences: DQP may have formed through a combination of shallow and some deep groundwater influx, while deep groundwater upwelling likely played the dominant role of salt formation at DJP. Our study seeks to understand the formation of DQP and DJP as unique terrestrial processes and as models for Ca, Cl, and S weathering and distribution on Mars.

  18. Active Cellular Mechanics and Information Processing in the Living Cell

    NASA Astrophysics Data System (ADS)

    Rao, M.

    2014-07-01

    I will present our recent work on the organization of signaling molecules on the surface of living cells. Using novel experimental and theoretical approaches we have found that many cell surface receptors are organized as dynamic clusters driven by active currents and stresses generated by the cortical cytoskeleton adjoining the cell surface. We have shown that this organization is optimal for both information processing and computation. In connecting active mechanics in the cell with information processing and computation, we bring together two of the seminal works of Alan Turing.

  19. Processing ISS Images of Titan's Surface

    NASA Technical Reports Server (NTRS)

    Perry, Jason; McEwen, Alfred; Fussner, Stephanie; Turtle, Elizabeth; West, Robert; Porco, Carolyn; Knowles, Ben; Dawson, Doug

    2005-01-01

    One of the primary goals of the Cassini-Huygens mission, in orbit around Saturn since July 2004, is to understand the surface and atmosphere of Titan. Surface investigations are primarily accomplished with RADAR, the Visual and Infrared Mapping Spectrometer (VIMS), and the Imaging Science Subsystem (ISS) [1]. The latter two use methane "windows", regions in Titan's reflectance spectrum where its atmosphere is most transparent, to observe the surface. For VIMS, this produces clear views of the surface near 2 and 5 microns [2]. ISS uses a narrow continuum band filter (CB3) at 938 nanometers. While these methane windows provide our best views of the surface, the images produced are not as crisp as ISS images of satellites like Dione and Iapetus [3] due to the atmosphere. Given a reasonable estimate of contrast (approx.30%), the apparent resolution of features is approximately 5 pixels due to the effects of the atmosphere and the Modulation Transfer Function of the camera [1,4]. The atmospheric haze also reduces contrast, especially with increasing emission angles [5].

  20. Chemical processes in Triton's atmosphere and surface

    NASA Astrophysics Data System (ADS)

    Delitsky, M. L.; Thompson, W. R.

    1987-05-01

    Liquid solutions of N2 containing up to one-third CH4 can exist on Triton's surface in regions T > 62.5K. More generally, subsurface oceans of N2 solution are expected to be stable beneath overlying, thermally insulating, less dense layers of the abundant light hydrocarbon products of radiochemical synthesis: C2H6, C3H8, and C4H10. Cosmic rays are the main source of energy, capable of producing synthesis of organic compounds from N2 - CH4 solutions on the surface. For baseline Triton models with R = 2500 km, ρ = 2.1 g cm-3, and Ts = 65 or 55K, respectively, 4×10-3 or 7×10-3erg cm-2sec-1 (49 or 87% of the total incident flux) is deposited within a few meters below the surface. Using yields from laboratory experiments, the authors estimate the quantities of products produced.

  1. The role of dynamic surface tension in cloud droplet activation

    NASA Astrophysics Data System (ADS)

    Petters, Markus D.; Suda, Sarah R.; Christensen, Sara I.

    2013-05-01

    We present new data on the cloud droplet forming abilities of two-component particles that contain the surfactant sodium dodecyl sulfate and sodium chloride or ammonium sulfate. The experiments were designed to test specific predictions made by Kohler theory that accounts for the reduction of surface tension and the partitioning of the surfactant between the interior and the surface of the droplet. We also introduced a pre-humidification step followed by a six minute time delay to test whether dynamic surface tension may lead to kinetic limitations on the partitioning process. Our results confirm previous studies that show that surfactants do not enhance cloud droplet activation relative to what would be predicted from water activity alone. The data obtained with and without time delay were indistinguishable within measurement uncertainty, suggesting that dynamic surface tension does not need to be considered in Kohler theory.

  2. Asphaltenes as a surface active agent

    SciTech Connect

    Sheu, E.Y.; Shields, M.B.; Storm, D.A.

    1995-12-31

    Asphaltene represents the heavy-end materials of the crude oil, conventionally defined via solvent solubility (either heptane or pentane). Chemically, it consists of polynuclear aromatics with the H/C ratio close to unity. Additionally, it contains a great deal of heteroatoms, such as sulfur, nitrogen, nickel, vanadium, etc. Several experiments have revealed the surface activity of asphaltenes in some selected solvents through measurements of their rheology or critical micelle concentrations in these solvents. The asphaltene micelles were found thermodynamically reversible. In a two phase asphaltene/water system, asphaltenes appear to vary their surface activities depending upon the polarity of the aqueous phase. Our recent experiment further showed that asphaltene/water/toluene may form, water-in-oil emulsion under certain conditions.

  3. The Exploration of Mars: Crew Surface Activities

    NASA Astrophysics Data System (ADS)

    Bhosri, Wisuwat; Cojanis, Philip; Gupta, Madhu; Khopkar, Manasi; Kiely, Aaron; Myers, Michael; Oxnevad, Knut; Sengupta, Anita; Sexton, Adam; Shaw, Don

    1999-01-01

    Surface activities of the first Mars mission crew, as suggested in phase I of the NASA HEDS reference mission, are discussed in this paper. The HEDS reference mission calls for a two phased approach. In phase I, humans supported by robotic systems will explore the Martian surface, collect and analyze geologic, geophysical, and meteorological data, search for potential permanent base sites, and conduct technology verification experiments. In phase II, a Mars base site will be selected, and the building of a permanent human base will be initiated. In this report two complementary architectures are portrayed. First, a permanent base for 3-6 people consisting of an ISRU unit, two nuclear power systems, a green house, and inflatable habitats and laboratories, built inside adobe structures. Second, a reusable, and resupplyable methane propelled very long range type traverse vehicle capable of collecting and analyzing data, and repairing and deploying scientific payloads during its planned 150 days 4800 km traverse. The very long range traverse vehicle will carry smaller rovers, crawlers, blimps, and an air drill capable of quickly reaching depths beyond 100m. The report presents a global vision of human activities on the surface of Mars at a programmatic level. It consists of several vignettes called "concept architectures" We speculate that these activities will facilitate a phase I Mars exploration architecture.

  4. Computer simulation of surface and film processes

    NASA Technical Reports Server (NTRS)

    Tiller, W. A.

    1981-01-01

    A molecular dynamics technique based upon Lennard-Jones type pair interactions is used to investigate time-dependent as well as equilibrium properties. The case study deals with systems containing Si and O atoms. In this case a more involved potential energy function (PEF) is employed and the system is simulated via a Monte-Carlo procedure. This furnishes the equilibrium properties of the system at its interfaces and surfaces as well as in the bulk.

  5. UMTRA Surface Project management action process document: Final. Revision 2

    SciTech Connect

    1996-06-01

    Title 1 of the UMTRCA authorized the DOE to undertake remedial actions at these designed sites and associated vicinity properties (VP), which contain uranium mill tailings and other residual radioactive materials (RRM) derived from the processing sites. Title 2 of the UMTRCA addresses uranium mill sites that were licensed at the time the UMTRCA was enacted. Cleanup of these Title 2 sites is the responsibility of the licensees. The cleanup of the Title 1 sites has been split into two separate projects: the Surface Project, which deals with the mill buildings, tailings, and contaminated soils at the sites and VPs; and the Ground Water Project, which is limited to the contaminated ground water at the sites. This management action process (MAP) document discusses the Uranium Mill Tailings Remedial Action (UMTRA) Surface Project. Since its inception through March 1996, the Surface Project (hereinafter called the Project) has cleaned up 16 of the 24 designated processing sites and approximately 5,000 VPs, reducing the risk to human health and the environment posed by the uranium mill tailings. Two of the 24 sites, Belfield and Bowman, North Dakota, will not be remediated at the request of the state, reducing the total number of sites to 22. By the start of FY1998, the remaining 6 processing sites and associated VPs will be cleaned up. The remedial action activities to be funded in FY1998 by the FY1998 budget request are remediation of the remaining Grand Junction, Colorado, VPs; closure of the Cheney disposal cell in Grand Junction, Colorado; and preparation of the completion reports for 4 completed sites.

  6. Electrolytic etching process provides effective bonding surface on stainless steel

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Electrolytic etching process prepares surfaces of a stainless steel shell for reliable, high strength adhesive bonding to dielectric materials. The process uses a 25 percent aqueous solution of phosphoric acid.

  7. Quantification of chemical transport processes from soil to surface runoff

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although there is a conceptual understanding on processes governing chemical transport from soil to surface runoff, there are little literature and research results actually quantifying these individual processes. We developed a laboratory flow cell and experimental procedures to quantify chemical ...

  8. Processes Impacting Atmosphere-Surface Exchanges at Arctic Terrestrial Sites

    NASA Astrophysics Data System (ADS)

    Persson, Ola; Grachev, Andrey; Konopleva, Elena; Cox, Chris; Stone, Robert; Crepinsek, Sara; Shupe, Matthew; Uttal, Taneil

    2015-04-01

    Surface energy fluxes are key to the annual cycle of near-surface and soil temperature and biologic activity in the Arctic. While these energy fluxes are undoubtedly changing to produce the changes observed in the Arctic ecosystem over the last few decades, measurements have generally not been available to quantify what processes are regulating these fluxes and what is determining the characteristics of these annual cycles. The U.S. National Oceanic and Atmospheric Administration has established, or contributed to the establishment of, several terrestrial "supersites" around the perimeter of the Arctic Ocean at which detailed measurements of atmospheric structure, surface fluxes, and soil thermal properties are being made. These sites include Barrow, Alaska; Eureka and Alert, Canada; and Tiksi, Russia. Atmospheric structure measurements vary, but include radiosoundings at all sites and remote sensing of clouds at two sites. Additionally, fluxes of sensible heat and momentum are made at all of the sites, while fluxes of moisture and CO2 are made at two of the sites. Soil temperatures are also measured in the upper 120 cm at all sites, which is deep enough to define the soil active layer. The sites have been operating between 3 years (Tiksi) and 24 years (Barrow). While all sites are located north of 71° N, the summer vegetation range from lush tundra grasses to rocky soils with little vegetation. This presentation will illustrate some of the atmospheric processes that are key for determining the annual energy and temperature cycles at these sites, and some of the key characteristics that lead to differences in, for instance, the length of the summer soil active layer between the sites. Atmospheric features and processes such as cloud characteristics, snowfall, downslope wind events, and sea-breezes have impacts on the annual energy cycle. The presence of a "zero curtain" period, when autumn surface temperature remains approximately constant at the freezing point

  9. Chemical processes in Triton's atmosphere and surface

    NASA Technical Reports Server (NTRS)

    Delitsky, M. L.; Thompson, W. R.

    1987-01-01

    The Neptune moon Triton may have an appreciable atmosphere; the preliminary calculations of Delitsky (1983) have suggested that there should be a significant resultant chemistry in a possible N2 ocean with dissolved CH4, given charged-particle radiolysis of gaseous mixtures and gamma radiolysis of N2-CH4 solutions. The latter will yield substantial quantities of organic products which will be partially soluble in any N2-CH4 liquid present. Attention is presently given to the energy sources available for Triton, in order to estimate rates of synthesis and ascertain the possible history of such simple and complex organic products on Triton's surface.

  10. Surface Electromyography Signal Processing and Classification Techniques

    PubMed Central

    Chowdhury, Rubana H.; Reaz, Mamun B. I.; Ali, Mohd Alauddin Bin Mohd; Bakar, Ashrif A. A.; Chellappan, Kalaivani; Chang, Tae. G.

    2013-01-01

    Electromyography (EMG) signals are becoming increasingly important in many applications, including clinical/biomedical, prosthesis or rehabilitation devices, human machine interactions, and more. However, noisy EMG signals are the major hurdles to be overcome in order to achieve improved performance in the above applications. Detection, processing and classification analysis in electromyography (EMG) is very desirable because it allows a more standardized and precise evaluation of the neurophysiological, rehabitational and assistive technological findings. This paper reviews two prominent areas; first: the pre-processing method for eliminating possible artifacts via appropriate preparation at the time of recording EMG signals, and second: a brief explanation of the different methods for processing and classifying EMG signals. This study then compares the numerous methods of analyzing EMG signals, in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above. PMID:24048337

  11. Evidence of Space Weathering Processes Across the Surface of Vesta

    NASA Technical Reports Server (NTRS)

    Pieters, Carle M.; Blewett, David T.; Gaffey, Michael; Mittlefehldt, David W.; CristinaDeSanctis, Maria; Reddy, Vishnu; Coradini, Angioletta; Nathues, Andreas; Denevi, Brett W.; Li, Jian-Yang; McCord, Thomas B.; Marchi, Simone; Palmer, Eric E.; Sunshine, Jessica M.; Filacchione, Gianrico; Ammannito, Eleonora; Raymond, Carol A.; Russell, Christopher T.

    2011-01-01

    relatively strong mafic absorption features, suggesting either a concentration of mafic materials or that materials exposed have been less affected by space weathering products. These combined initial observations indicate some space weathering processes are active in this part of the main asteroid belt, but are highly variable across the surface of Vesta. Such processes include: impacts from wandering asteroidal debris and local mixing at both micro- and macro-scales, irradiation by solar wind and galactic particles, production and distribution of impact breccias or melt products, and local movement of materials to gravity lows (gradual as well as sudden).

  12. Lunar surface processes - Report of the 12054 consortium

    NASA Technical Reports Server (NTRS)

    Hartung, J. B.; Hauser, E. E.; Horz, F.; Morrison, D. A.; Schonfeld, E.; Zook, H. A.; Mandeville, J.-C.; Mcdonnell, J. A. M.; Schaal, R. B.; Zinner, E.

    1978-01-01

    A variety of lunar surface phenomena were studied using a well-characterized glass-coated ilmenite basalt, 12054, which had a simple surface residence history. Surface processes related to the following effects were studied: microcraters, solar flare and cosmic ray tracks, cosmogenic Al-26, solar wind sputtering, accreta or accretionary material, solar wind implanted noble gases, and loose dust accumulation.

  13. A generic rate law for surface-active enzymes.

    PubMed

    Kartal, Onder; Ebenhöh, Oliver

    2013-09-02

    Many biochemical reactions are confined to interfaces, such as membranes or cell walls. Despite their importance, no canonical rate laws describing the kinetics of surface-active enzymes exist. Combining the approach chosen by Michaelis and Menten 100 years ago with concepts from surface chemical physics, we here present an approach to derive generic rate laws of enzymatic processes at surfaces. We illustrate this by a simple reversible conversion on a surface to stress key differences to the classical case in solution. The available area function, a concept from surface physics which enters the rate law, covers different models of adsorption and presents a unifying perspective on saturation effects and competition between enzymes. A remarkable implication is the direct dependence of the rate of a given enzyme on all other enzymatic species able to bind at the surface. The generic approach highlights general principles of the kinetics of surface-active enzymes and allows to build consistent mathematical models of more complex pathways involving reactions at interfaces.

  14. Motility of active fluid drops on surfaces

    NASA Astrophysics Data System (ADS)

    Khoromskaia, Diana; Alexander, Gareth P.

    2015-12-01

    Drops of active liquid crystal have recently shown the ability to self-propel, which was associated with topological defects in the orientation of active filaments [Sanchez et al., Nature 491, 431 (2013), 10.1038/nature11591]. Here, we study the onset and different aspects of motility of a three-dimensional drop of active fluid on a planar surface. We analyze theoretically how motility is affected by orientation profiles with defects of various types and locations, by the shape of the drop, and by surface friction at the substrate. In the scope of a thin drop approximation, we derive exact expressions for the flow in the drop that is generated by a given orientation profile. The flow has a natural decomposition into terms that depend entirely on the geometrical properties of the orientation profile, i.e., its bend and splay, and a term coupling the orientation to the shape of the drop. We find that asymmetric splay or bend generates a directed bulk flow and enables the drop to move, with maximal speeds achieved when the splay or bend is induced by a topological defect in the interior of the drop. In motile drops the direction and speed of self-propulsion is controlled by friction at the substrate.

  15. Modeling of surface microtopography and its impacts on hydrologic processes

    NASA Astrophysics Data System (ADS)

    Habtezion, Noah Lebassi

    Understanding the impacts of surface microtopography on hydrologic processes is critical. The objectives of this thesis research are: (1) to evaluate the effects of DEM resolution on microtopographic characteristics, hydrologic connectivity, and modeling of hydrologic processes; and (2) to assess the influences of multiple rainfall events on surface and subsurface hydrologic processes with the use of a puddle-to-puddle (P2P) modeling system. The change in DEM resolution has a significant effect on how surface microtopography is depicted, which in turn alters the hydrologic response of a topographic surface. The smoothing of reduced DEM resolution tends to enhance hydrologic connectivity, reduce the depression storage and infiltration, and increase surface runoff. Temporal rainfall distribution results in spatio-temporal variations in soil water dynamics, depression storage, infiltration, hydrologic connectivity, and surface runoff. The reduction in ponding time and infiltration, and the enhancement of hydrologic connectivity further caused earlier and greater surface runoff generation.

  16. Attention to surfaces modulates motion processing in extrastriate area MT.

    PubMed

    Wannig, Aurel; Rodríguez, Valia; Freiwald, Winrich A

    2007-05-24

    In the visual system, early atomized representations are grouped into higher-level entities through processes of perceptual organization. Here we present neurophysiological evidence that a representation of a simple object, a surface defined by color and motion, can be the unit of attentional selection at an early stage of visual processing. Monkeys were cued by the color of a fixation spot to attend to one of two transparent random-dot surfaces, one red and one green, which occupied the same region of space. Motion of the attended surface drove neurons in the middle temporal (MT) visual area more strongly than physically identical motion of the non-attended surface, even though both occurred within the spotlight of attention. Surface-based effects of attention persisted even without differential surface coloring, but attentional modulation was stronger with color. These results show that attention can select surface representations to modulate visual processing as early as cortical area MT.

  17. Titanium nanostructural surface processing for improved biocompatibility

    SciTech Connect

    Cheng, H.-C.; Lee, S.-Y.; Chen, C.-C.; Shyng, Y.-C.; Ou, K.-L.

    2006-10-23

    X-ray photoelectron spectroscopy, grazing incident x-ray diffraction, transmission electron microscopy, and scanning electron microscopy were conducted to evaluate the effect of titanium hydride on the formation of nanoporous TiO{sub 2} on Ti during anodization. Nano-titanium-hydride was formed cathodically before anodizing and served as a sacrificial nanoprecipitate during anodization. Surface oxidation occurred and a multinanoporous structure formed after cathodic pretreatments followed by anodization treatment. The sacrificial nanoprecipitate is directly dissolved and the Ti transformed to nanoporous TiO{sub 2} by anodization. The formation of sacrificial nanoprecipitates by cathodic pretreatment and of the multinanostructure by anodization is believed to improve biocompatibility, thereby promoting osseointegration.

  18. Chemical processes in Triton's atmosphere and surface

    SciTech Connect

    Delitsky, M.L.; Thompson, W.R.

    1987-05-01

    The Neptune moon Triton may have an appreciable atmosphere; the preliminary calculations of Delitsky (1983) have suggested that there should be a significant resultant chemistry in a possible N/sub 2/ ocean with dissolved CH/sub 4/, given charged-particle radiolysis of gaseous mixtures and gamma radiolysis of N/sub 2/-CH/sub 4/ solutions. The latter will yield substantial quantities of organic products which will be partially soluble in any N/sub 2/-CH/sub 4/ liquid present. Attention is presently given to the energy sources available for Triton, in order to estimate rates of synthesis and ascertain the possible history of such simple and complex organic products on Triton's surface. 54 references.

  19. Indium phosphide negative electron affinity photocathodes: Surface cleaning and activation

    NASA Astrophysics Data System (ADS)

    Sun, Yun

    InP(100) is a very important semi-conductor for many applications. When activated by Cs and oxygen, the InP surface achieves the state of Negative Electron Affinity (NEA) making the Cs+O/InP system a very efficient electron source. Despite many years of study, the chemical cleaning and activation of InP are still not well understood. In our work, we have established an understanding of the basic physics and chemistry for the chemical cleaning and activation of the InP(100) surface. Synchrotron Radiation Photoelectron Spectroscopy is the main technique used in this study because of its high surface sensitivity and ability to identify chemical species present on the surface at each stage of our process. A clean, stoichiometric InP(100) surface is crucial for obtaining high performance of NEA photocathodes. Therefore, the first part of our study focused on the chemical cleaning of InP(100). We found that hydrogen peroxide based solutions alone, originally developed to clean GaAs(100) surfaces and widely used for InP(100), do not result in clean InP(I00) surfaces because oxide is left on the surface. A second cleaning step, which uses acid solutions like HCl or H2SO4, can remove all the oxide and leave a 0.4 ML protective layer of elemental phosphorous on the surface. The elemental phosphorous can be removed by annealing at 330°C and a clean InP(100) surface can be obtained. Cs deposition on InP(100) surface shows clear charge transfer from the Cs ad-atoms to the substrate. When the Cs/InP(100) surface is dosed with oxygen, the charge transfer from the Cs to substrate is reduced and substrate is oxidized. The activation of InP as a NEA photocathode is carried out by an alternating series of steps consisting of Cs deposition and Cs+O co-deposition. Two types of oxygen are found after activation. The first is dissociated oxygen and the other is a di-oxygen species (peroxide or superoxide). The decay of quantum-yield with time and with annealing is studied and changes in

  20. Documenting Biophysical Activities on Land Surfaces

    NASA Astrophysics Data System (ADS)

    Gobron, N.; Pinty, B.; Melin, F.; Taberner, M.; Verstraete, M. M.; Widlowski, J.

    2002-12-01

    The biophysical activities on land surfaces have been documented from spectral measurements made in space for decades. These estimates often were derived from the Normalized Difference Vegetation Index, which is simple to compute but very sensitive to perturbations and prone to yield misleading or erroneous results. Advances in the understanding of radiation transfer and availability of higher performance instruments have lead to the development of a new generation of geophysical products poised to provide reliable, accurate information on the state and evolution of terrestrial environments. Specifically, a series of optimized algorithms have been developed to estimate the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) for various instruments. Such an approach allows the synergistic use of FAPAR products derived from different sensors and the construction of global FAPAR time series independent from the life time of these specific sensors. The outline of the methodology will be summarized and the results from an application conducted with SeaWiFS data will be presented.

  1. Process for laser machining and surface treatment

    DOEpatents

    Neil, George R.; Shinn, Michelle D.

    2004-10-26

    An improved method and apparatus increasing the accuracy and reducing the time required to machine materials, surface treat materials, and allow better control of defects such as particulates in pulsed laser deposition. The speed and quality of machining is improved by combining an ultrashort pulsed laser at high average power with a continuous wave laser. The ultrashort pulsed laser provides an initial ultrashort pulse, on the order of several hundred femtoseconds, to stimulate an electron avalanche in the target material. Coincident with the ultrashort pulse or shortly after it, a pulse from a continuous wave laser is applied to the target. The micromachining method and apparatus creates an initial ultrashort laser pulse to ignite the ablation followed by a longer laser pulse to sustain and enlarge on the ablation effect launched in the initial pulse. The pulse pairs are repeated at a high pulse repetition frequency and as often as desired to produce the desired micromachining effect. The micromachining method enables a lower threshold for ablation, provides more deterministic damage, minimizes the heat affected zone, minimizes cracking or melting, and reduces the time involved to create the desired machining effect.

  2. Computer simulation of surface and film processes

    NASA Technical Reports Server (NTRS)

    Tiller, W. A.; Halicioglu, M. T.

    1984-01-01

    All the investigations which were performed employed in one way or another a computer simulation technique based on atomistic level considerations. In general, three types of simulation methods were used for modeling systems with discrete particles that interact via well defined potential functions: molecular dynamics (a general method for solving the classical equations of motion of a model system); Monte Carlo (the use of Markov chain ensemble averaging technique to model equilibrium properties of a system); and molecular statics (provides properties of a system at T = 0 K). The effects of three-body forces on the vibrational frequencies of triatomic cluster were investigated. The multilayer relaxation phenomena for low index planes of an fcc crystal was analyzed also as a function of the three-body interactions. Various surface properties for Si and SiC system were calculated. Results obtained from static simulation calculations for slip formation were presented. The more elaborate molecular dynamics calculations on the propagation of cracks in two-dimensional systems were outlined.

  3. Data processing method based on surface and tangent vector deviations for freeform surface

    NASA Astrophysics Data System (ADS)

    Hou, Wei; Zhu, Jun; Yang, Tong; Jin, Guo-an

    2013-08-01

    Surface measurement and analysis are important to freeform surface optical systems. The deviation from designed surface is generally regarded as a judging criterion of real surface quality. In off-axis optical systems, some freeform surfaces contain no reference points. Measured data of such surfaces can only constitute a fitted surface, but the spatial position of the fitted surface is difficult to be determined to make a smallest deviation from designed surface by internal algorithms. In freeform surface optical systems, besides the surface deviations, the tangent vector variations of lattice data of measured surface can also affect the image quality. Consequently the quality of freeform surface should be appraised by both of tangent vector variations and surface deviations. This paper presents one method using first-order differential to directly analyze and process the measured lattice data of freeform surfaces. This method assesses the tangent vector variations of measured data and the smoothness of real surfaces, while does not involve the fitting procedure with designed surfaces. In this paper, this method is applied to evaluate a set of measured lattice data of some reflective freeform surfaces. Furthermore, some fitting algorithms are applied to assess the surface deviations between the measured and designed surfaces as contrasts.

  4. Computer simulation of surface and film processes

    NASA Technical Reports Server (NTRS)

    Tiller, W. A.; Halicioglu, M. T.

    1983-01-01

    Adequate computer methods, based on interactions between discrete particles, provide information leading to an atomic level understanding of various physical processes. The success of these simulation methods, however, is related to the accuracy of the potential energy function representing the interactions among the particles. The development of a potential energy function for crystalline SiO2 forms that can be employed in lengthy computer modelling procedures was investigated. In many of the simulation methods which deal with discrete particles, semiempirical two body potentials were employed to analyze energy and structure related properties of the system. Many body interactions are required for a proper representation of the total energy for many systems. Many body interactions for simulations based on discrete particles are discussed.

  5. Thermal and Nonthermal Processes on Single Crystal Transition Metal Surfaces

    NASA Astrophysics Data System (ADS)

    Guo, Xingcai

    This dissertation contains three parts. Part I, "Fundamentals", provides concise description of concepts, detailed accounts of historic studies, and extensive reviews of current activities. Chapter 1 deals with thermal processes (adsorption and desorption), and Chapter 2 with nonthermal processes induced by electrons and by photons. Part II, "Experimental" (Chapter 3), describes the ultrahigh vacuum apparatus, surface science techniques, and procedures for single crystal preparation and gas exposure. Part III, "Results", is a collection of ten selected publications in refereed journals. Each chapter is self-contained. Thermal desorption of CO from Pd(111) (Chapter 4) has been studied by temperature programmed desorption. It is demonstrated that the effective desorption kinetic parameters extracted from desorption spectra are correlated with the adlayer structures and dependent on the sizes of ordered domains--a nonequilibrium effect. Site exchange of CO (Chapter 5) and site retention of O_2 (Chapter 6) on Pt(112) during thermal desorption are observed with isotope labeled adsorption on specific sites--steps or terraces. The adsorption and desorption kinetics of O _2 are compared on Pt(111) and Pt(112) surfaces (Chapter 7). The mechanisms of adsorption and the effect of well-defined defects are elucidated. O_2 adsorbed on Pd(111) is studied with thermal activation (Chapter 8), electron impact (Chapter 9), and photon irradiation (Chapter 10 -12). Various thermal processes are delineated with isotopic mixing experiments. Electron-induced conversion, dissociation, and desorption processes are observed. Cross sections (10^{-17} cm^2 ) and their electron energy dependences (0-500 eV) are measured. A resonance-enhanced desorption of atomic oxygen from Pd(111) is found at ~10 eV. Photon-induced conversion, dissociation, and desorption processes are observed. Cross sections (10^ {-19} cm^2) and photon energy dependence (1.4-5.4 eV) are extracted. Possible mechanisms are

  6. Particle engineering in pharmaceutical solids processing: surface energy considerations.

    PubMed

    Williams, Daryl R

    2015-01-01

    During the past 10 years particle engineering in the pharmaceutical industry has become a topic of increasing importance. Engineers and pharmacists need to understand and control a range of key unit manufacturing operations such as milling, granulation, crystallisation, powder mixing and dry powder inhaled drugs which can be very challenging. It has now become very clear that in many of these particle processing operations, the surface energy of the starting, intermediate or final products is a key factor in understanding the processing operation and or the final product performance. This review will consider the surface energy and surface energy heterogeneity of crystalline solids, methods for the measurement of surface energy, effects of milling on powder surface energy, adhesion and cohesion on powder mixtures, crystal habits and surface energy, surface energy and powder granulation processes, performance of DPI systems and finally crystallisation conditions and surface energy. This review will conclude that the importance of surface energy as a significant factor in understanding the performance of many particulate pharmaceutical products and processes has now been clearly established. It is still nevertheless, work in progress both in terms of development of methods and establishing the limits for when surface energy is the key variable of relevance.

  7. Energetics of active transport processes.

    PubMed

    Essig, A; Caplan, S R

    1968-12-01

    Discussions of active transport usually assume stoichiometry between the rate of transport J(+) and the metabolic rate J(r). However, the observation of a linear relationship between J(+) and J(r) does not imply a stoichiometric relationship, i.e., complete coupling. Since coupling may possibly be incomplete, we examine systems of an arbitrary degree of coupling q, regarding stoichiometry as a limiting case. We consider a sodium pump, with J(+) and J(r) linear functions of the electrochemical potential difference, -X(+), and the chemical affinity of the metabolic driving reaction, A. The affinity is well defined even for various complex reaction pathways. Incorporation of a series barrier and a parallel leak does not affect the linearity of the composite observable system. The affinity of some region of the metabolic chain may be maintained constant, either by large pools of reactants or by regulation. If so, this affinity can be evaluated by two independent methods. Sodium transport is conveniently characterized by the open-circuit potential (Deltapsi)(I=0) and the natural limits, level flow (J(+))(X+=0), and static head X(0) (+) = (X(+))(J+=0). With high degrees of coupling -X(0) (+)/F approaches the electromotive force E(Na) (Ussing); -X(0) (+)/F cannot be identified with ((RT/F) ln f)(X+=0), where f is the flux ratio. The efficiency eta = -J(+)X(+)/J(r)A is of significance only when appreciable energy is being converted from one form to another. When either J(+) or -X(+) is small eta is low; the significant parameters are then the efficacies epsilon(J+) = J(+)/J(r)A and epsilon(X+) = -X(+)/J(r)A, respectively maximal at level flow and static head. Leak increases both J(+) and epsilon(J+) for isotonic saline reabsorption, but diminishes -X(0) (+) and epsilon(Xfemale symbol). Electrical resistance reflects both passive parameters and metabolism. Various fundamental relations are preserved despite coupling of passive ion and water flows.

  8. Equilibrium fluctuations in the theory of surface processes on microparticles

    NASA Astrophysics Data System (ADS)

    Tovbin, Yu. K.

    2010-11-01

    The question of the role of equilibrium fluctuations in the adsorption theory and kinetics of surface processes occurring on the particles of the nanometer size range is discussed. Differences are put forward that need to be introduced to the fluctuation theory of surface processes on microparticles and that generalize Hill's approach to describing the thermodynamic properties of small systems. We show the importance of allowing for the discrete character of adsorption centers on the surfaces and their heterogeneity when describing adsorption isotherms and the rates of adsorption processes.

  9. Ionic surface active compounds in atmospheric aerosols.

    PubMed

    Sukhapan, Jariya; Brimblecombe, Peter

    2002-04-27

    Surfactants in the atmosphere have several potential roles in atmospheric chemistry. They can form films on aqueous surfaces, which lowers the surface tension and possibly delays water evaporation and gaseous transportation across the aqueous interface. They can also increase the solubility of organic compounds in the aqueous phase. Recently, the decrease of surface tension in cloud growing droplets has been suggested as relevant to increases in the number of droplets of smaller size, potentially enhancing cloud albedo. Natural surfactants in the lung aid gas transfer and influence the dissolution rate of aerosol particles, so surfactants in atmospheric aerosols, once inhaled, may interact with pulmonary surfactants. Ambient aerosols were collected from the edge of Norwich, a small city in a largely agricultural region of England, and analysed for surfactants. Methylene blue, a conventional dye for detecting anionic surfactants, has been used as a colorimetric agent. The concentration of surfactants expressed as methylene blue active substances (MBAS) is in the range of 6-170 pmol m(-3)(air). A negative correlation with chloride aerosol indicates that these surfactants are probably not the well-known surfactants derived from marine spray. A more positive correlation with aerosol nitrate and gaseous NOx supports an association with more polluted inland air masses. The surfactants found in aerosols seem to be relatively strong acids, compared with weaker acids such as the long-chain carboxylic acids previously proposed as atmospheric surfactants. Surfactants from the oxidation of organic materials (perhaps vegetation- or soil-derived) seem a likely source of these substances in the atmosphere.

  10. Homogeneous near surface activity distribution by double energy activation for TLA

    NASA Astrophysics Data System (ADS)

    Takács, S.; Ditrói, F.; Tárkányi, F.

    2007-10-01

    Thin layer activation (TLA) is a versatile tool for activating thin surface layers in order to study real-time the surface loss by wear, corrosion or erosion processes of the activated parts, without disassembling or stopping running mechanical structures or equipment. The research problem is the determination of the irradiation parameters to produce point-like or large area optimal activity-depth distribution in the sample. Different activity-depth profiles can be produced depending on the type of the investigated material and the nuclear reaction used. To produce activity that is independent of the depth up to a certain depth is desirable when the material removed from the surface by wear, corrosion or erosion can be collected completely. By applying dual energy irradiation the thickness of this quasi-constant activity layer can be increased or the deviation of the activity distribution from a constant value can be minimized. In the main, parts made of metals and alloys are suitable for direct activation, but by using secondary particle implantation the wear of other materials can also be studied in a surface range a few micrometers thick. In most practical cases activation of a point-like spot (several mm2) is enough to monitor the wear, corrosion or erosion, but for special problems relatively large surfaces areas of complicated spatial geometry need to be activated uniformly. Two ways are available for fulfilling this task, (1) production of large area beam spot or scanning the beam over the surface in question from the accelerator side, or (2) a programmed 3D movement of the sample from the target side. Taking into account the large variability of tasks occurring in practice, the latter method was chosen as the routine solution in our cyclotron laboratory.

  11. Surface etching and roughening in integrated processing of thermal oxides

    NASA Astrophysics Data System (ADS)

    Offenberg, M.; Liehr, M.; Rubloff, G. W.

    1991-04-01

    A multichamber UHV processing and analysis system has been used to study integrated thermal oxide processing, in which the final precleaning process and the thermal oxidation process are integrated by employing transfer of the wafers through ultraclean, inert ambients (purified, dry N2 and then ultrahigh vacuum). The Al-gate MOS capacitors show high breakdown fields (approximately 12 MV/cm) when a thin oxide passivation layer is present prior to oxidation, but low fields (less than 6 MV/cm) when the Si surface is initially oxygen free. This contrasting behavior is caused by the etching of Si surfaces which occurs at elevated temperature in the presence of trace concentration (approximately 100 ppb) of oxygen (e.g., 2 Si + O2 yields 2SiO2), leading to surface roughening and then field enhancement at asperities in the structure. Oxide surface passivation prevents etching and assures the dielectric integrity of the structure.

  12. Adaptive control of surface finish in automated turning processes

    NASA Astrophysics Data System (ADS)

    García-Plaza, E.; Núñez, P. J.; Martín, A. R.; Sanz, A.

    2012-04-01

    The primary aim of this study was to design and develop an on-line control system of finished surfaces in automated machining process by CNC turning. The control system consisted of two basic phases: during the first phase, surface roughness was monitored through cutting force signals; the second phase involved a closed-loop adaptive control system based on data obtained during the monitoring of the cutting process. The system ensures that surfaces roughness is maintained at optimum values by adjusting the feed rate through communication with the PLC of the CNC machine. A monitoring and adaptive control system has been developed that enables the real-time monitoring of surface roughness during CNC turning operations. The system detects and prevents faults in automated turning processes, and applies corrective measures during the cutting process that raise quality and reliability reducing the need for quality control.

  13. Surface activity of solid particles with extremely rough surfaces.

    PubMed

    Nonomura, Yoshimune; Komura, Shigeyuki

    2008-01-15

    The solid particles are adsorbed at liquid-liquid interfaces and form self-assembled structures when the particles have suitable wettability to both liquids. Here, we show theoretically how the extreme roughness on the particle surface affects their adsorption properties. In our previous work, we discussed the adsorption behavior of the solid particles with microstructured surfaces using the so-called Wenzel model [Y. Nonomura et al., J. Phys. Chem. B 110 (2006) 13124]. In the present study, the wettability and the adsorbed position of the particles with extremely rough surfaces are studied based on the Cassie-Baxter model. We predict that the adsorbed position and the interfacial energy depend on the interfacial tensions between the solid and liquid phases, the radius of the particle, and the fraction of the particle surface area that is in contact with the external liquid phase. Interestingly, the initial state of the system governs whether the particle is adsorbed at the interface or not. The shape of the particle is also an important factor which governs the adsorbed position. The disk-shaped particle and the spherical particle which is partially covered with the extremely rough surface, i.e. Janus particle, are adsorbed at the liquid-liquid interface in an oriented state. We should consider not only the interfacial tensions, but also the surface structure and the particle shape to control the adsorption behavior of the particle.

  14. Surface plasmon amplification and active nonreciprocal gratings

    NASA Astrophysics Data System (ADS)

    Karami Keshmarzi, Elham; Tait, R. Niall; Berini, Pierre

    2015-03-01

    In this paper, we review our recent work on active plasmonic structures composed of optically pumped dye molecules infiltrated in a polymer host as the cladding of long-range surface plasmon polariton (LRSPP) structures. In particular, concepts for distributed Bragg and distributed feedback (DBR/DFB) lasers, and a spatially non-reciprocal Bragg grating (NRBG) are reviewed. The LRSPP Bragg grating is a fundamental element in these devices which is created by stepping the width of a metal stripe to produce modulation of refractive index. The gain medium in all of these active devices is assumed to be a thin film (~1μm) of polymer (poly (methyl methacrylate)) doped with organic laser dye molecules IR- 140. The gain medium is assumed pumped optically through the top of the devices via 10 ns laser pulses at 810 nm with 500 kW/cm2 power intensity to enable stimulated emission at 880 nm. The maximum material gain coefficient of this medium was measured independently as 68 cm-1.

  15. Protein immobilization and detection on laser processed polystyrene surfaces

    NASA Astrophysics Data System (ADS)

    Sarantopoulou, Evangelia; Petrou, Panagiota S.; Kollia, Zoe; Palles, Dimitrios; Spyropoulos-Antonakakis, Nikolaos; Kakabakos, Sotirios; Cefalas, Alkiviadis-Constantinos

    2011-09-01

    The bovine serum albumin (BSA)-polystyrene (PS) interface layer is laser photo activated at 157 nm for site selective multiple target-protein immobilization. The 5-15 nm photon induced interface layer has different chemical, wetting, and stiffness properties than the PS photon processed surface. The irradiated areas exhibit target-protein binding, followed by localized probe-target protein detection. The photon induced chemical modification of the BSA-PS interface layer is identified by: (1) Morphological, imaging, and analysis of surface parameters with atomic force microscopy, (2) spectroscopic shift (4 cm-1), of the amide I group and formation of new C=N, NH2, C-O, C=O, and O-C=O groups following irradiation, identified with attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and (3) the different hydrophilic/hydrophobic and force-distance response of the bare PS and BSA-PS surfaces. Near field edge diffraction (Fresnel) fluorescence imaging specifies the threshold photon energy and the fluence required to optically detect the protein binding on the photon induced BSA-PS interface layer. By approximating the Fresnel integrals with analytical functions, the threshold photon energy and the fluence are expressed as the sum of zero, first, and second order harmonic terms of two characteristic diffracted modes and they are specified to be 8.73×10-9Jand623 J m-2, respectively. Furthermore, a bioarray of three probe-target proteins is fabricated with 1.5 μm spatial resolution using a 157 nm laser microstepper. The methodology eliminates the use of intermediate polymer layers between the blocking BSA protein and the PS substrate in bioarray fabrication.

  16. Protein immobilization and detection on laser processed polystyrene surfaces

    SciTech Connect

    Sarantopoulou, Evangelia; Kollia, Zoe; Palles, Dimitrios; Spyropoulos-Antonakakis, Nikolaos; Cefalas, Alkiviadis-Constantinos; Petrou, Panagiota S.; Kakabakos, Sotirios

    2011-09-15

    The bovine serum albumin (BSA)-polystyrene (PS) interface layer is laser photo activated at 157 nm for site selective multiple target-protein immobilization. The 5-15 nm photon induced interface layer has different chemical, wetting, and stiffness properties than the PS photon processed surface. The irradiated areas exhibit target-protein binding, followed by localized probe-target protein detection. The photon induced chemical modification of the BSA-PS interface layer is identified by: (1) Morphological, imaging, and analysis of surface parameters with atomic force microscopy, (2) spectroscopic shift (4 cm{sup -1}), of the amide I group and formation of new C=N, NH{sub 2}, C-O, C=O, and O-C=O groups following irradiation, identified with attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and (3) the different hydrophilic/hydrophobic and force-distance response of the bare PS and BSA-PS surfaces. Near field edge diffraction (Fresnel) fluorescence imaging specifies the threshold photon energy and the fluence required to optically detect the protein binding on the photon induced BSA-PS interface layer. By approximating the Fresnel integrals with analytical functions, the threshold photon energy and the fluence are expressed as the sum of zero, first, and second order harmonic terms of two characteristic diffracted modes and they are specified to be 8.73x10{sup -9} Jand623 J m{sup -2}, respectively. Furthermore, a bioarray of three probe-target proteins is fabricated with 1.5 {mu}m spatial resolution using a 157 nm laser microstepper. The methodology eliminates the use of intermediate polymer layers between the blocking BSA protein and the PS substrate in bioarray fabrication.

  17. Apparatus and process for the surface treatment of carbon fibers

    SciTech Connect

    Paulauskas, Felix Leonard; Ozcan, Soydan; Naskar, Amit K.

    2016-05-17

    A method for surface treating a carbon-containing material in which carbon-containing material is reacted with decomposing ozone in a reactor (e.g., a hollow tube reactor), wherein a concentration of ozone is maintained throughout the reactor by appropriate selection of at least processing temperature, gas stream flow rate, reactor dimensions, ozone concentration entering the reactor, and position of one or more ozone inlets (ports) in the reactor, wherein the method produces a surface-oxidized carbon or carbon-containing material, preferably having a surface atomic oxygen content of at least 15%. The resulting surface-oxidized carbon material and solid composites made therefrom are also described.

  18. Quantitative evolution of volcanic surfaces affected by erosional processes

    NASA Astrophysics Data System (ADS)

    Lahitte, Pierre; Boillot-Airaksinen, Kim; Germa, Aurélie; Lavigne, Franck

    2016-04-01

    Variations through time of erosion dynamics, a key point to investigate correlation between climates and landform evolution, still remains poorly documented. One of the main issue in this type of study is the difficulty in determining for how long the erosion has operated. For this purpose, volcanic contexts are particularly suitable for defining the temporal dynamics governing erosion since the age of volcanic activity also constrains the age of emplacement of the surface today eroded, and thus the erosion duration. Furthermore, quantitative analysis of river profiles offers the opportunity to discriminate, among the wide variety of geological phenomena influencing erosion, their respective influence. Quantification of erosion processes and constrain of their signature on reliefs can be addressed by a morphometric approach of river profiles in volcanic environment through the analysis of digital topography (DEM). Break in slope zones, the so-called knickpoints, are usually related to a retreat of the point between the relict channel, upstream, and the adjusted channel, downstream. They are induced by either a lithological contrast, a change in the base level, uplift or eustatism, or a rejuvenation of the age of the volcanic surface. The stream long-profile and its watershed is also investigated by their concavity and hypsometric indexes to determine for how long the complexity and its heterogeneity along the valley incision remain visible. The present study focusses on the erosion of volcanoes in the Lesser Antilles, Reunion Island and Lombok Island (Indonesia). All located in tropical environments, these volcanoes offer a wide diversity of age (30 - 0 Ma) and lithology for investigating the respective influence of geological processes that have induced a large variety of shapes and volcanic history that we try to correlate to geometry of river profiles.

  19. Fractionation of Zr and Hf in surface processes

    SciTech Connect

    Chyi, L.L.; Garg, A.N.

    1985-01-01

    Zircons from a pegmatite near Tuxedo, North Carolina were crushed and treated with different reagents under different conditions. The treated and untreated samples were determined for Zr and Hf with radiochemical neutron activation analysis. Zircons treated with 50% sulfuric acid were having lowered Zr content and Zr/Hf ratio. The conclusions are that a portion of Zr and Hf in zircons is sensitive to leaching, and Zr appears to be selectively leached over Hf. The conclusions of this work support the observations of small dissolutions of Zr in both acidic podzolic soils and in alkaline laterites, of lower Zr content in soils on glacial drift, and of lower Zr/Hf ratios in loess deposits from various parts of the world. The fractionation of Zr and Hf in surface processes appears to be due to selective leaching. Weakening of Zr-O over Hf-O bonds in zircon by fission projectiles is postulated to be the viable process. The observed fractionation from leaching experiments suggest that areas receiving leachates such as swamps, lakes, and oceans should have high to very high Zr/Hf ratios preserved in rocks. High ratios are found in the Springfield (No. 9) Coal, the Green River Shale, and various limestones. High ratio is also found in orchard leaves, which grow by absorbing leachate from soil.

  20. Surface engineering of glazing materials and structures using plasma processes

    SciTech Connect

    Anders, Andre; Monteiro, Othon R.

    2003-04-10

    A variety of coatings is commercially produced on a very large scale, including transparent conducting oxides and multi-layer silver-based low-emissivity and solar control coatings. A very brief review of materials and manufacturing process is presented and illustrated by ultrathin silver films and chevron copper films. Understanding the close relation between manufacturing processes and bulk and surface properties of materials is crucial for film growth and self-assembly processes.

  1. Surface processing for bulk niobium superconducting radio frequency cavities

    NASA Astrophysics Data System (ADS)

    Kelly, M. P.; Reid, T.

    2017-04-01

    The majority of niobium cavities for superconducting particle accelerators continue to be fabricated from thin-walled (2–4 mm) polycrystalline niobium sheet and, as a final step, require material removal from the radio frequency (RF) surface in order to achieve performance needed for use as practical accelerator devices. More recently bulk niobium in the form of, single- or large-grain slices cut from an ingot has become a viable alternative for some cavity types. In both cases the so-called damaged layer must be chemically etched or electrochemically polished away. The methods for doing this date back at least four decades, however, vigorous empirical studies on real cavities and more fundamental studies on niobium samples at laboratories worldwide have led to seemingly modest improvements that, when taken together, constitute a substantial advance in the reproducibility for surface processing techniques and overall cavity performance. This article reviews the development of niobium cavity surface processing, and summarizes results of recent studies. We place some emphasis on practical details for real cavity processing systems which are difficult to find in the literature but are, nonetheless, crucial for achieving the good and reproducible cavity performance. New approaches for bulk niobium surface treatment which aim to reduce cost or increase performance, including alternate chemical recipes, barrel polishing and ‘nitrogen doping’ of the RF surface, continue to be pursued and are closely linked to the requirements for surface processing.

  2. Characterization of cathode keeper wear by surface layer activation

    NASA Technical Reports Server (NTRS)

    Polk, James E.

    2003-01-01

    In this study, the erosion rates of the discharge cathode keeper in a 30 cm NSTAR configuration ion thruster were measured using a technique known as Surface Layer Activation (SLA). This diagnostic technique involves producing a radioactive tracer in a given surface by bombardment with high energy ions. The decrease in activity of the tracer material may be monitored as the surface is subjected to wear processes and correlated to a depth calibration curve, yielding the eroded depth. Analysis of the activities was achieved through a gamma spectroscopy system. The primary objectives of this investigation were to reproduce erosion data observed in previous wear studies in order to validate the technique, and to determine the effect of different engine operating parameters on erosion rate. The erosion profile at the TH 15 (23 kw) setting observed during the 8200 hour Life Demonstration Test (LDT) was reproduced. The maximum keeper erosion rate at this setting was determined to be 0.085 pm/hr. Testing at the TH 8 (1.4 kw) setting demonstrated lower erosion rates than TH 15, along with a different wear profile. Varying the keeper voltage was shown to have a significant effect on the erosion, with a positive bias with respect to cathode potential decreasing the erosion rate significantly. Accurate measurements were achieved after operating times of only 40 to 70 hours, a significant improvement over other erosion diagnostic methods.

  3. The effect of processing variables on steel surface chemistry

    SciTech Connect

    Shaw, G.S.

    1993-12-31

    Differences in processing at all stages in the steel making process can effect the surface chemistry of steel. The surface chemistry can dictate the performance of many different products and processes including electrogalvanized steel. If the steel chemistry is not controlled sufficiently, the zinc electrodeposit will be subject to hydrogen blistering. This dissertation examined the effect of many processing variables on both the organic and inorganic contaminants on steel surfaces. Processes both before the electrogalvanizing line and those after the electrogalvanizing line were examined. Mechanisms were determined for reactions of organic oils with the steel surface. Reaction between the carbonyl functionality, present as an acid or an ester, and iron hydroxide to form a tenaciously adherent iron soap was demonstrated using infrared spectroscopy and mass spectrometry. Thermodynamics and kinetics of segregation of metallic elements to the surface of the steel were determined. It was shown that the primary mechanism for segregation of elements such as aluminum, silicon, chromium, and titanium is oxidation during the anneal. Analysis of the kinetics indicated the feasibility of this mechanism. The mechanism of electrocleaning were elucidated, based on both electrochemical and physical effects. Improved methods of electrocleaning were described based upon optimization of the cleaning frequency. It was found that increasing the frequency of anodic and cathodic cycling increasing the cleaning efficiency up to about 5 Hz. Above this frequency bubbles, which provide physical scrubbing and convection near the interface, can not form rapidly enough to be effective. Increased current density was shown to be effective in improving electrocleaning.

  4. Status and directions of modified tribological surfaces by ion processes

    NASA Technical Reports Server (NTRS)

    Spalvins, Talivaldis

    1988-01-01

    An overview is presented of recent advances in modifying contacting surfaces in motion by the various ion assisted surface coating/modification processes to reduce and control tribological failures. The ion assisted coating processes and the surface modification processes offer the greatest potential to custom tailor and optimize the tribological performance. Hard, wear resistant and low shear coatings deposited by the ion assisted processes are discussed. Primarily the recent advances of sputtered MoS2 ion plated Au, Ag, Pb lubricating films and sputtered and ion plated hard, wear resistant TiN, HfN, TiC films are described in terms of structural property performance interrelationships which lead to improved adhesion, cohesion, nucleation, morphological growth, density, film thickness as determined by structural and chemical characterization and frictional and wear behavior. Also, the recent tribological advances using the surface modification processes such as ion implantation, ion beam mixing is discussed with emphasis on the development of lubricous high temperature ceramic surfaces.

  5. Influence of the morphology on the platinum electrode surface activity

    NASA Astrophysics Data System (ADS)

    Reiner, Andreas; Steiger, Beat; Scherer, Günther G.; Wokaun, Alexander

    Polycrystalline Pt electrodes with different surface characteristics were investigated by cyclic voltammetry (CV) in 0.5 M H 2SO 4. Plane electrodes showed a decrease in electrochemically active surface area while cycling in the hydrogen underpotential region (H upd), in contrast, electrodes roughened by intensive pre-cycling exhibited a stable value for the electrochemically active surface.

  6. Plasma assisted surface coating/modification processes - An emerging technology

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1987-01-01

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation. These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  7. Plasma assisted surface coating/modification processes: An emerging technology

    NASA Astrophysics Data System (ADS)

    Spalvins, T.

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation). These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  8. Plasma assisted surface coating/modification processes - An emerging technology

    NASA Astrophysics Data System (ADS)

    Spalvins, T.

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation. These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  9. Representing Global Reactive Potential Energy Surfaces Using Gaussian Processes.

    PubMed

    Kolb, Brian; Marshall, Paul; Zhao, Bin; Jiang, Bin; Guo, Hua

    2017-03-23

    Representation of multidimensional global potential energy surfaces suitable for spectral and dynamical calculations from high-level ab initio calculations remains a challenge. Here, we present a detailed study on constructing potential energy surfaces using a machine learning method, namely, Gaussian process regression. Tests for the (3)A″ state of SH2, which facilitates the SH + H ↔ S((3)P) + H2 abstraction reaction and the SH + H' ↔ SH' + H exchange reaction, suggest that the Gaussian process is capable of providing a reasonable potential energy surface with a small number (∼1 × 10(2)) of ab initio points, but it needs substantially more points (∼1 × 10(3)) to converge reaction probabilities. The implications of these observations for construction of potential energy surfaces are discussed.

  10. Plasma assisted surface coating/modification processes: An emerging technology

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1986-01-01

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation). These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  11. Report of the panel on the land surface: Process of change, section 5

    NASA Technical Reports Server (NTRS)

    Adams, John B.; Barron, Eric E.; Bloom, Arthur A.; Breed, Carol; Dohrenwend, J.; Evans, Diane L.; Farr, Thomas T.; Gillespie, Allan R.; Isaks, B. L.; Williams, Richard S.

    1991-01-01

    The panel defined three main areas of study that are central to the Solid Earth Science (SES) program: climate interactions with the Earth's surface, tectonism as it affects the Earth's surface and climate, and human activities that modify the Earth's surface. Four foci of research are envisioned: process studies with an emphasis on modern processes in transitional areas; integrated studies with an emphasis on long term continental climate change; climate-tectonic interactions; and studies of human activities that modify the Earth's surface, with an emphasis on soil degradation. The panel concluded that there is a clear requirement for global coverage by high resolution stereoscopic images and a pressing need for global topographic data in support of studies of the land surface.

  12. New journal to provide venue for rigorous surface process work

    NASA Astrophysics Data System (ADS)

    Grant, Shermonta

    Robert S. Anderson, an AGU member (Hydrology) since 1987, has been selected as editor of a new section of JGR, titled Earth Surface, scheduled to begin in the spring of 2003. This new section will focus on surficial processes; in particular, the physical, chemical, and biological processes that affect the form and function of the surface of the solid Earth over all temporal and spatial scales.Anderson told Eos, "I want this journal to serve as an outlet for science that applies rigorous quantitative methods to surface process problems; and through publication, to promote this approach to such problems," emphasizing that the section could be a primary venue for science performed by individuals or small teams. Currently articles related to this discipline are printed in various publications, including some AGU journals. But with an increase in the number of scientists working in this area, a publication designated to this subject is critical.

  13. Poorly processed reusable surface disinfection tissue dispensers may be a source of infection

    PubMed Central

    2014-01-01

    Background Reusable surface disinfectant tissue dispensers are used in hospitals in many countries because they allow immediate access to pre-soaked tissues for targeted surface decontamination. On the other hand disinfectant solutions with some active ingredients may get contaminated and cause outbreaks. We determined the frequency of contaminated surface disinfectant solutions in reusable dispensers and the ability of isolates to multiply in different formulations. Methods Reusable tissue dispensers with different surface disinfectants were randomly collected from healthcare facilities. Solutions were investigated for bacterial contamination. The efficacy of two surface disinfectants was determined in suspension tests against two isolated species directly from a contaminated solution or after 5 passages without selection pressure in triplicate. Freshly prepared use solutions were contaminated to determine survival of isolates. Results 66 dispensers containing disinfectant solutions with surface-active ingredients were collected in 15 healthcare facilities. 28 dispensers from nine healthcare facilities were contaminated with approximately 107 cells per mL of Achromobacter species 3 (9 hospitals), Achromobacter xylosoxidans or Serratia marcescens (1 hospital each). In none of the hospitals dispenser processing had been adequately performed. Isolates regained susceptibility to the disinfectants after five passages without selection pressure but were still able to multiply in different formulations from different manufacturers at room temperature within 7 days. Conclusions Neglecting adequate processing of surface disinfectant dispensers has contributed to frequent and heavy contamination of use-solutions based on surface active ingredients. Tissue dispenser processing should be taken seriously in clinical practice. PMID:24447780

  14. Process Produces Low-Secondary-Electron-Emission Surfaces

    NASA Technical Reports Server (NTRS)

    Curren, A. N.; Jensen, K. A.; Roman, R. F.

    1986-01-01

    Textured carbon layer applied to copper by sputtering. Carbon surface characterized by dense, random array of needle-like spires or peaks that extend perpendicularly from local copper surface. Spires approximately 7 micrometers in height and spaced approximately 3 micrometers apart, on average. Copper substrate essentially completely covered by carbon layer, is tenacious and not damaged by vibration loadings representative of multistage depressed collector (MDC) applications. Process developed primarily to provide extremely low-secondary-electron-emission surface for copper for use as highefficiency electrodes in MDC's for microwave amplifier traveling-wave tubes (TWT's). Tubes widely used in space communications, aircraft, and terrestrial applications.

  15. System and process for detecting and monitoring surface defects

    NASA Technical Reports Server (NTRS)

    Mueller, Mark K. (Inventor)

    1994-01-01

    A system and process for detecting and monitoring defects in large surfaces such as the field joints of the container segments of a space shuttle booster motor. Beams of semi-collimated light from three non-parallel fiber optic light panels are directed at a region of the surface at non-normal angles of expected incidence. A video camera gathers some portion of the light that is reflected at an angle other than the angle of expected reflectance, and generates signals which are analyzed to discern defects in the surface. The analysis may be performed by visual inspection of an image on a video monitor, or by inspection of filtered or otherwise processed images. In one alternative embodiment, successive predetermined regions of the surface are aligned with the light source before illumination, thereby permitting efficient detection of defects in a large surface. Such alignment is performed by using a line scan gauge to sense the light which passes through an aperture in the surface. In another embodiment a digital map of the surface is created, thereby permitting the maintenance of records detailing changes in the location or size of defects as the container segment is refurbished and re-used. The defect detection apparatus may also be advantageously mounted on a fixture which engages the edge of a container segment.

  16. Laser-Stimulated Surface Processes and Heterogeneous Catalysis.

    DTIC Science & Technology

    1980-11-01

    A07-AC94 337 ROCHESTER UNIV NY DEPT OF CI4EMISTRY F/* 7/5 LASER-STINULATED SURFACE PROCESSES AND HETEROGENEOUS CATALYSIS . (Ul UN, NOV 80 J LIN N00014...Contra" W014-80-C-OD472 Task No. NR 056-749 __ TECHNICAL REPORT NO. 8 I Laser-Stimulated Surface Processes) *.and Heterogeneous Catalysis .) by / J...Repor HETEROGENEOUS CATALYSIS InterimTechnical_______ 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(*) S. CONTRACT OR GRANT NUMSER(.) Jui-teng Lin N00014

  17. Structure-process-property relations in excimer laser surface processed Ti-6Al-4V alloy

    SciTech Connect

    Jervis, T.R.; Zocco, T.G.; Steele, J.H. Jr.

    1990-01-01

    Excimer laser processing results in very rapid solidification of metal surfaces. In addition to mixing or segregation processes, rapid heat treatment can result in phase transformations which yield beneficial surface properties. We have investigated the effect of pulsed excimer laser radiation on the microstructure and surface hardness of Ti-6Al-4V alloy. This material undergoes a well defined martensite transformation during rapid quenching from temperatures in the {beta} phase field. The depth of the transformed layer is thus a marker for the temperature profile during processing. We find that the depth of the transformed layer agrees well with a simple 1-D calculation of heat flow following the laser pulse. As measured by the nanoindenter, we find that the surface martensite is softer than the as-rolled alloy. Multiple pulse processing at high fluences results in an increase in surface hardness, but at a depth much less than that of the martensite, suggesting an independent mechanism. 10 refs., 4 figs.

  18. Topographic Slope, Solar Radiation and Land Surface Processes

    NASA Astrophysics Data System (ADS)

    Mosor, A. L.; Hahmann, A. N.

    2001-12-01

    The Earth's surface is composed of non-uniform terrain, which partially controls the amount of incident radiation available at the surface and in turn controls its regional vegetation cover and its hydrological and ecological processes. A complete treatment of the physical mechanisms that determine a region's climate should include a detailed description of its land surface processes. The processes associated with net solar radiation and surface water movements are sensitive to the degree to which the surface slope and aspect are approximated. Therefore, a careful representation of land surface-atmosphere transfer interactions requires the terrain to be viewed as separate homogenous sub-regions of different slope and aspect, particularly over complex terrain. This study describes a mathematical representation of the surface topography developed to provide an aggregated measure of the radiative effects on inclined terrain. We have obtained a "radiative equivalent" topography (i.e., elevation, slope, and aspect), for use as boundary conditions to a fine-mesh land model coupled to the NCAR Community Climate Model (CCM3). Using the data sets developed at the U.S Geological Survey Data Center (at 1 km resolution), we have derived aggregated slopes and aspects at the 0.5 o x 0.5 o fine-mesh resolution. The aggregated slopes and aspects are used in an off-line test using BATS for the Arizona region. This test indicates considerable differences in the latent and sensible heat fluxes between the "flat" terrain simulation and that where slopes and azimuths are considered in the computation of the incident solar radiation. This poster will present the results of a more complete test of the effects of incorporating the effective incident solar radiation of inclined surfaces on the climate. In particular, the effects on snow hydrology over the Western United States will be explored.

  19. Novel Psbnd O codoped g-C3N4 with large specific surface area: Hydrothermal synthesis assisted by dissolution-precipitation process and their visible light activity under anoxic conditions

    NASA Astrophysics Data System (ADS)

    Ma, Huiqiang; Li, Yang; Li, Shuang; Liu, Na

    2015-12-01

    Novel Psbnd O codoped g-C3N4 with large specific surface area is hydrothermal synthesized assisted by dissolution-precipitation process. The XRD, UV-vis, SEM and PL results indicate that the introduction of phosphorus and oxygen enhances the specific surface area of graphitic carbon nitride (from 12.8 to 92.5 m2 g-1), restrains the crystal growth, decreases the band gap energy (from 2.68 to 2.51 eV) and increases the separation efficiency of photogenerated electrons and holes, which increases the anoxic photocatalytic RhB degradation constants by approximately 27 times under visible light. Oxygen doping not only promotes the adsorption ability of reactant but also captures the photogenerated electrons to produce photogenerated holes for RhB degradation under anoxic condition. This study provides new insight into the design and fabrication of oxygen-free photocatalysts.

  20. Remote sensing data assimilation in land surface process modelling

    NASA Astrophysics Data System (ADS)

    Bach, Heike; Mauser, Wolfram

    2002-01-01

    Land surface process models describe the energy-, water-, carbon- and nutrient-fluxes at the land surface on a regional scale by combining a given set of environmental parameters and variables (e.g. water balance model, plant physiology model, atmospheric boundary layer model, erosion model). They need spatially distributed input parameters, which can be delivered from remote sensing analyses using both optical and microwave sensors. Thus, land surface process models are the main drivers for four dimensional data assimilation (4DDA) which is based on the synergistic data utilization of remote sensing and ancillary data both in space and time. To ensure the constant flow of the necessary input parameters and variables, the development of adequate data-assimilation and data-fusion techniques is mandatory. Parameter models operate at the centre of this data fusion process to convert remote sensing measurements into a set of model input parameters and variables. Different strategies to use remote sensing derived parameters in models are demonstrated. They span from the simple delivery of static input-parameters, over the provision of dynamic model parameters, model forcing and recalibration of internal model variables, to inversion and validation of land surface process models. Examples will illustrate these different data assimilation strategies using SAR and optical data sources. The integration of land surface parameters derived from remote sensing (e.g. land use, digital terrain model, surface soil moisture) in flood forecast is a rather straight forward task. For water balance modelling, soil moisture and snow cover assessment will be illustrated. This task is already more complex, since a continuous process must be simulated and the data assimilation must avoid inconsistencies in model performance. The application of remote sensing data assimilation methods for crop growth and agricultural production models further requires complex feedback mechanisms. Examples

  1. Active control of compressible flows on a curved surface

    NASA Technical Reports Server (NTRS)

    Maestrello, L.; Parikh, P.; Bayliss, A.; Turkel, E.

    1985-01-01

    The effect of localized, time periodic surface heating and cooling over a curved surface is studied. This is a mechanism for the active control of unstable disturbances by phase cancellation and reinforcement. It is shown that the pressure gradient induced by the curvature significantly enhances the effectiveness of this form of active control. In particular, by appropriate choice of phase, active surface heating can completely stabilize and unstable wave.

  2. Active control of compressible flows on a curved surface

    NASA Technical Reports Server (NTRS)

    Maestrello, L.; Bayliss, A.; Parikh, P.; Turkel, E.

    1985-01-01

    The effect of localized, time periodic surface heating and cooling over a curved surface is studied. This is a mechanism for the active control of unstable disturbances by phase cancellation and reinforcement. It is shown that the pressure gradient induced by the curvature significantly enhances the effectiveness of this form of active control. In particular, by appropriate choice of phase, active surface heating can completely stabilize an unstable wave.

  3. Surface modification of magnesium hydroxide using vinyltriethoxysilane by dry process

    NASA Astrophysics Data System (ADS)

    Lan, Shengjie; Li, Lijuan; Xu, Defang; Zhu, Donghai; Liu, Zhiqi; Nie, Feng

    2016-09-01

    In order to improve the compatibility between magnesium hydroxide (MH) and polymer matrix, the surface of MH was modified using vinyltriethoxysilane (VTES) by dry process and the interfacial interaction between MH and VTES was also studied. Zeta potential measurements implied that the MH particles had better dispersion and less aggregation after modification. Sedimentation tests showed that the surface of MH was transformed from hydrophilic to hydrophobic, and the dispersibility and the compatibility of MH particles significantly improved in the organic phase. Scanning electronic microscopy (SEM), Transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analyses showed that a thin layer had formed on the surface of the modified MH, but did not alter the material's crystalline phase. Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectra (XPS) and Thermogravimetric analysis (TGA) showed that the VTES molecules bound strongly to the surface of MH after modification. Chemical bonds (Sisbnd Osbnd Mg) formed by the reaction between Si-OC2H5 and hydroxyl group of MH, also there have physical adsorption effect in the interface simultaneously. A modification mechanism of VTES on the MH surface by dry process was proposed, which different from the modification mechanism by wet process.

  4. Process for producing an activated carbon adsorbent with integral heat transfer apparatus

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor); Yavrouian, Andre H. (Inventor)

    1996-01-01

    A process for producing an integral adsorbent-heat exchanger apparatus useful in ammonia refrigerant heat pump systems. In one embodiment, the process wets an activated carbon particles-solvent mixture with a binder-solvent mixture, presses the binder wetted activated carbon mixture on a metal tube surface and thereafter pyrolyzes the mixture to form a bonded activated carbon matrix adjoined to the tube surface. The integral apparatus can be easily and inexpensively produced by the process in large quantities.

  5. Process entanglement as a neuronal anchorage mechanism to rough surfaces

    NASA Astrophysics Data System (ADS)

    Sorkin, Raya; Greenbaum, Alon; David-Pur, Moshe; Anava, Sarit; Ayali, Amir; Ben-Jacob, Eshel; Hanein, Yael

    2009-01-01

    The organization of neurons and glia cells on substrates composed of pristine carbon nanotube islands was investigated using high resolution scanning electron microscopy, immunostaining and confocal microscopy. Neurons were found bound and preferentially anchored to the rough surfaces; moreover, the morphology of the neuronal processes on the small, isolated islands of high density carbon nanotubes was found to be conspicuously curled and entangled. We further demonstrate that the roughness of the surface must match the diameter of the neuronal processes in order to allow them to bind. The results presented here suggest that entanglement, a mechanical effect, may constitute an additional mechanism by which neurons (and possibly other cell types) anchor themselves to rough surfaces. Understanding the nature of the interface between neurons and carbon nanotubes is essential to effectively harness carbon nanotube technology in neurological applications such as neuro-prosthetic and retinal electrodes.

  6. Process for producing cadmium sulfide on a cadmium telluride surface

    DOEpatents

    Levi, D.H.; Nelson, A.J.; Ahrenkiel, R.K.

    1996-07-30

    A process is described for producing a layer of cadmium sulfide on a cadmium telluride surface to be employed in a photovoltaic device. The process comprises providing a cadmium telluride surface which is exposed to a hydrogen sulfide plasma at an exposure flow rate, an exposure time and an exposure temperature sufficient to permit reaction between the hydrogen sulfide and cadmium telluride to thereby form a cadmium sulfide layer on the cadmium telluride surface and accomplish passivation. In addition to passivation, a heterojunction at the interface of the cadmium sulfide and the cadmium telluride can be formed when the layer of cadmium sulfide formed on the cadmium telluride is of sufficient thickness. 12 figs.

  7. Process to restore obliterated serial numbers on metal surfaces

    NASA Technical Reports Server (NTRS)

    Young, S. G.; Parker, B.; Chisum, W. J.

    1974-01-01

    Metal smeared into grooves of serial numbers by grinding or filing can be cleaned out by process called cavitation. Ultrasonic vibrator generates very high frequency vibrations in water which create millions of microscopic bubbles. Cavitation bubbles impact metal surface at thousands of pounds per square inch pressure. Metal particles filling grooves are broken away.

  8. Processing of Color Words Activates Color Representations

    ERIC Educational Resources Information Center

    Richter, Tobias; Zwaan, Rolf A.

    2009-01-01

    Two experiments were conducted to investigate whether color representations are routinely activated when color words are processed. Congruency effects of colors and color words were observed in both directions. Lexical decisions on color words were faster when preceding colors matched the color named by the word. Color-discrimination responses…

  9. Using Satellite Imagery and Google Tools to Teach Planetary Surface Forming Processes. (Invited)

    NASA Astrophysics Data System (ADS)

    Baldridge, A. M.

    2013-12-01

    Space and planetary science topics are included as an important part of an introductory physical geology course to give students the ability to understand and interpret satellite imagery and have a broad, synergistic understanding of surface processes. Geologic processes are grouped into four categories: Volcanism, Tectonism, Gradation, and Impact Cratering. Using investigations with GoogleEarth, GoogleMars and additional satellite images of solid surface bodies in the Solar System students: - explore the size, shapes and distribution of volcanoes and lava flows - investigate and identify types of sand dunes, river beds, and other fluvial deposits - determine if linear features are tectonic in nature - examine impact cratering and dating of planetary surfaces The degree to which a planet is geological active can be determined by investigating these 'planetary surface-forming processes.' By understanding how surface features are created (and destroyed) on solid surface planetary bodies students learn what it means for a surface to be geologically young and factors that contribute to make planet Earth a special and unique place. This presentation will describe the activities, resources and practices for exploring these processes in the classroom.

  10. Molecular reordering processes on ice (0001) surfaces from long timescale simulations

    NASA Astrophysics Data System (ADS)

    Pedersen, Andreas; Wikfeldt, Kjartan T.; Karssemeijer, Leendertjan; Cuppen, Herma; Jónsson, Hannes

    2014-12-01

    We report results of long timescale adaptive kinetic Monte Carlo simulations aimed at identifying possible molecular reordering processes on both proton-disordered and ordered (Fletcher) basal plane (0001) surfaces of hexagonal ice. The simulations are based on a force field for flexible molecules and span a time interval of up to 50 μs at a temperature of 100 K, which represents a lower bound to the temperature range of earth's atmosphere. Additional calculations using both density functional theory and an ab initio based polarizable potential function are performed to test and refine the force field predictions. Several distinct processes are found to occur readily even at this low temperature, including concerted reorientation (flipping) of neighboring surface molecules, which changes the pattern of dangling H-atoms, and the formation of interstitial defects by the downwards motion of upper-bilayer molecules. On the proton-disordered surface, one major surface roughening process is observed that significantly disrupts the crystalline structure. Despite much longer simulation time, such roughening processes are not observed on the highly ordered Fletcher surface which is energetically more stable because of smaller repulsive interaction between neighboring dangling H-atoms. However, a more localized process takes place on the Fletcher surface involving a surface molecule transiently leaving its lattice site. The flipping process provides a facile pathway of increasing proton-order and stabilizing the surface, supporting a predominantly Fletcher-like ordering of low-temperature ice surfaces. Our simulations also show that eventual proton-disordered patches on the surface may induce significant local reconstructions. Further, a subset of the molecules on the Fletcher surface are susceptible to forming interstitial defects which might provide active sites for various chemical reactions in the atmosphere.

  11. Molecular reordering processes on ice (0001) surfaces from long timescale simulations

    SciTech Connect

    Pedersen, Andreas; Wikfeldt, Kjartan T.; Karssemeijer, Leendertjan; Cuppen, Herma; Jónsson, Hannes

    2014-12-21

    We report results of long timescale adaptive kinetic Monte Carlo simulations aimed at identifying possible molecular reordering processes on both proton-disordered and ordered (Fletcher) basal plane (0001) surfaces of hexagonal ice. The simulations are based on a force field for flexible molecules and span a time interval of up to 50 μs at a temperature of 100 K, which represents a lower bound to the temperature range of earth's atmosphere. Additional calculations using both density functional theory and an ab initio based polarizable potential function are performed to test and refine the force field predictions. Several distinct processes are found to occur readily even at this low temperature, including concerted reorientation (flipping) of neighboring surface molecules, which changes the pattern of dangling H-atoms, and the formation of interstitial defects by the downwards motion of upper-bilayer molecules. On the proton-disordered surface, one major surface roughening process is observed that significantly disrupts the crystalline structure. Despite much longer simulation time, such roughening processes are not observed on the highly ordered Fletcher surface which is energetically more stable because of smaller repulsive interaction between neighboring dangling H-atoms. However, a more localized process takes place on the Fletcher surface involving a surface molecule transiently leaving its lattice site. The flipping process provides a facile pathway of increasing proton-order and stabilizing the surface, supporting a predominantly Fletcher-like ordering of low-temperature ice surfaces. Our simulations also show that eventual proton-disordered patches on the surface may induce significant local reconstructions. Further, a subset of the molecules on the Fletcher surface are susceptible to forming interstitial defects which might provide active sites for various chemical reactions in the atmosphere.

  12. Giant and switchable surface activity of liquid metal via surface oxidation

    PubMed Central

    Khan, Mohammad Rashed; Eaker, Collin B.; Bowden, Edmond F.; Dickey, Michael D.

    2014-01-01

    We present a method to control the interfacial tension of a liquid alloy of gallium via electrochemical deposition (or removal) of the oxide layer on its surface. In sharp contrast with conventional surfactants, this method provides unprecedented lowering of surface tension (∼500 mJ/m2 to near zero) using very low voltage, and the change is completely reversible. This dramatic change in the interfacial tension enables a variety of electrohydrodynamic phenomena. The ability to manipulate the interfacial properties of the metal promises rich opportunities in shape-reconfigurable metallic components in electronic, electromagnetic, and microfluidic devices without the use of toxic mercury. This work suggests that the wetting properties of surface oxides—which are ubiquitous on most metals and semiconductors—are intrinsic “surfactants.” The inherent asymmetric nature of the surface coupled with the ability to actively manipulate its energetics is expected to have important applications in electrohydrodynamics, composites, and melt processing of oxide-forming materials. PMID:25228767

  13. Modeling of electrohydrodynamic drying process using response surface methodology.

    PubMed

    Dalvand, Mohammad Jafar; Mohtasebi, Seyed Saeid; Rafiee, Shahin

    2014-05-01

    Energy consumption index is one of the most important criteria for judging about new, and emerging drying technologies. One of such novel and promising alternative of drying process is called electrohydrodynamic (EHD) drying. In this work, a solar energy was used to maintain required energy of EHD drying process. Moreover, response surface methodology (RSM) was used to build a predictive model in order to investigate the combined effects of independent variables such as applied voltage, field strength, number of discharge electrode (needle), and air velocity on moisture ratio, energy efficiency, and energy consumption as responses of EHD drying process. Three-levels and four-factor Box-Behnken design was employed to evaluate the effects of independent variables on system responses. A stepwise approach was followed to build up a model that can map the entire response surface. The interior relationships between parameters were well defined by RSM.

  14. Modeling of electrohydrodynamic drying process using response surface methodology

    PubMed Central

    Dalvand, Mohammad Jafar; Mohtasebi, Seyed Saeid; Rafiee, Shahin

    2014-01-01

    Energy consumption index is one of the most important criteria for judging about new, and emerging drying technologies. One of such novel and promising alternative of drying process is called electrohydrodynamic (EHD) drying. In this work, a solar energy was used to maintain required energy of EHD drying process. Moreover, response surface methodology (RSM) was used to build a predictive model in order to investigate the combined effects of independent variables such as applied voltage, field strength, number of discharge electrode (needle), and air velocity on moisture ratio, energy efficiency, and energy consumption as responses of EHD drying process. Three-levels and four-factor Box–Behnken design was employed to evaluate the effects of independent variables on system responses. A stepwise approach was followed to build up a model that can map the entire response surface. The interior relationships between parameters were well defined by RSM. PMID:24936289

  15. Speech perception as an active cognitive process.

    PubMed

    Heald, Shannon L M; Nusbaum, Howard C

    2014-01-01

    One view of speech perception is that acoustic signals are transformed into representations for pattern matching to determine linguistic structure. This process can be taken as a statistical pattern-matching problem, assuming realtively stable linguistic categories are characterized by neural representations related to auditory properties of speech that can be compared to speech input. This kind of pattern matching can be termed a passive process which implies rigidity of processing with few demands on cognitive processing. An alternative view is that speech recognition, even in early stages, is an active process in which speech analysis is attentionally guided. Note that this does not mean consciously guided but that information-contingent changes in early auditory encoding can occur as a function of context and experience. Active processing assumes that attention, plasticity, and listening goals are important in considering how listeners cope with adverse circumstances that impair hearing by masking noise in the environment or hearing loss. Although theories of speech perception have begun to incorporate some active processing, they seldom treat early speech encoding as plastic and attentionally guided. Recent research has suggested that speech perception is the product of both feedforward and feedback interactions between a number of brain regions that include descending projections perhaps as far downstream as the cochlea. It is important to understand how the ambiguity of the speech signal and constraints of context dynamically determine cognitive resources recruited during perception including focused attention, learning, and working memory. Theories of speech perception need to go beyond the current corticocentric approach in order to account for the intrinsic dynamics of the auditory encoding of speech. In doing so, this may provide new insights into ways in which hearing disorders and loss may be treated either through augementation or therapy.

  16. Evaluation of Select Surface Processing Techniques for In Situ Application During the Additive Manufacturing Build Process

    NASA Astrophysics Data System (ADS)

    Book, Todd A.; Sangid, Michael D.

    2016-07-01

    Although additive manufacturing offers numerous performance advantages for different applications, it is not being used for critical applications due to uncertainties in structural integrity as a result of innate process variability and defects. To minimize uncertainty, the current approach relies on the concurrent utilization of process monitoring, post-processing, and non-destructive inspection in addition to an extensive material qualification process. This paper examines an alternative approach by evaluating the application of select surface process techniques, to include sliding severe plastic deformation (SPD) and fine particle shot peening, on direct metal laser sintering-produced AlSi10Mg materials. Each surface processing technique is compared to baseline as-built and post-processed samples as a proof of concept for surface enhancement. Initial results pairing sliding SPD with the manufacture's recommended thermal stress relief cycle demonstrated uniform recrystallization of the microstructure, resulting in a more homogeneous distribution of strain among the microstructure than as-built or post-processed conditions. This result demonstrates the potential for the in situ application of various surface processing techniques during the layerwise direct metal laser sintering build process.

  17. Experimental investigation of the laser ablation process on wood surfaces

    NASA Astrophysics Data System (ADS)

    Panzner, M.; Wiedemann, G.; Henneberg, K.; Fischer, R.; Wittke, Th.; Dietsch, R.

    1998-05-01

    Processing of wood by conventional mechanical tools like saws or planes leaves behind a layer of squeezed wood only slightly adhering to the solid wood surface. Laser ablation of this layer could improve the durability of coatings and glued joints. For technical applications, thorough knowledge about the laser ablation process is necessary. Results of ablation experiments by excimer lasers, Nd:YAG lasers, and TEA-CO 2 lasers on surfaces of different wood types and cut orientations are shown. The process of ablation was observed by a high-speed camera system and optical spectroscopy. The influence of the experimental parameters are demonstrated by SEM images and measurement of the ablation rate depending on energy density. Thermal effects like melting and also carbonizing of cellulose were found for IR- and also UV-laser wavelengths. Damage of the wood surface after laser ablation was weaker for excimer lasers and CO 2-TEA lasers. This can be explained by the high absorption of wood in the ultraviolet and middle infrared spectral range. As an additional result, this technique provides an easy way for preparing wood surfaces with excellently conserved cellular structure.

  18. The Role of Surface Layer Processes in Solid Propellant Combustion.

    NASA Astrophysics Data System (ADS)

    Chakravarthy, Satyanarayanan R.

    The qualitative multidimensional theory of composite solid propellant combustion based on the sandwich burning methodology was applied to certain specific problems: (a) burning rate enhancement by ferric oxide, (b) plateau burning behavior caused by binder melt flow effects, and (c) characterization of the combustion of new energetic oxidizers--ADN and HNIW. Exothermic reactions at the interfacial contact lines between AP particles and the binder in the surface layer of the burning propellant assume significance in the presence of ferric oxide, and control the burning rate. Binder melt flow covers adjacent AP particle surfaces increasingly at higher pressures, and disperses the O/F leading edge flames attached to coarse particles. It also causes fine AP/binder matrix areas on the surface not to support a steady premixed flame at intermediate pressures, resulting in an overall decrease in the burning rate with increasing pressure, which implies plateau or mesa effects. ADN self -deflagration rate is significantly higher than that of AP, and controls the sandwich burning rate to a great extent. The O/F flame of ADN and binder still behaves as rate limiting, although strongly supported by ADN self-deflagration. ADN melts and vaporizes substantially before the binder, allowing for the possibility of complex physical processes in the surface layer. The strong exothermic decomposition of HNIW at moderate temperatures causes the oxidizer particles in the surface layer to be the sites of burning rate control. The problems addressed in this study combinedly point to the significance of crucial surface layer processes under the situations of interest, and signal a need to characterize such processes directly and in greater detail.

  19. Controlling contagion processes in activity driven networks.

    PubMed

    Liu, Suyu; Perra, Nicola; Karsai, Márton; Vespignani, Alessandro

    2014-03-21

    The vast majority of strategies aimed at controlling contagion processes on networks consider the connectivity pattern of the system either quenched or annealed. However, in the real world, many networks are highly dynamical and evolve, in time, concurrently with the contagion process. Here, we derive an analytical framework for the study of control strategies specifically devised for a class of time-varying networks, namely activity-driven networks. We develop a block variable mean-field approach that allows the derivation of the equations describing the coevolution of the contagion process and the network dynamic. We derive the critical immunization threshold and assess the effectiveness of three different control strategies. Finally, we validate the theoretical picture by simulating numerically the spreading process and control strategies in both synthetic networks and a large-scale, real-world, mobile telephone call data set.

  20. Requirements for extravehicular activities on the lunar and Martian surfaces

    NASA Technical Reports Server (NTRS)

    Brown, Mariann F.; Schentrup, Susan M.

    1990-01-01

    Basic design reference requirements pertinent to EVA equipment on lunar and martian surfaces are provided. Environmental factors affecting surface EVA are analyzed including gravity, dust, atmospheric conditions, thermal gradients, lightning conditions, and radiation effects, and activities associated with surface EVA are outlined. Environmental and activity effects on EVA equipment are assessed, and emphasis is placed on planetary surface portable life support systems (PLSS), suit development, protection from micrometeoroids, dust, and radiation, food and water supplies, and the extravehicular mobility-unit thermal-control system. Environmental and activity impacts on PLSS design are studied, with focus on base self-sufficiency and reduction in resupply logistics.

  1. Control surface spanwise placement in active flutter suppression systems

    NASA Technical Reports Server (NTRS)

    Nissim, E.; Burken, J. J.

    1989-01-01

    All flutter suppression systems require sensors to detect the movement of the lifting surface and to activate a control surface according to a synthesized control law. Most of the work performed to date relates to the development of control laws based on predetermined locations of sensors and control surfaces. These locations of sensors and control surfaces are determined either arbitrarily, or by means of a trial and error procedure. The aerodynamic energy concept indicates that the sensors should be located within the activated strip. Furthermore, the best chordwise location of a sensor activating a T.E. control surface is around the 65 percent chord location. The best chordwise location for a sensor activating a L.E. surface is shown to lie upstream of the wing (around 20 percent upstream of the leading edge), or alternatively, two sensors located along the same chord should be used.

  2. High surface area activated carbon prepared from cassava peel by chemical activation.

    PubMed

    Sudaryanto, Y; Hartono, S B; Irawaty, W; Hindarso, H; Ismadji, S

    2006-03-01

    Cassava is one of the most important commodities in Indonesia, an agricultural country. Cassava is one of the primary foods in our country and usually used for traditional food, cake, etc. Cassava peel is an agricultural waste from the food and starch processing industries. In this study, this solid waste was used as the precursor for activated carbon preparation. The preparation process consisted of potassium hydroxide impregnation at different impregnation ratio followed by carbonization at 450-750 degrees C for 1-3 h. The results revealed that activation time gives no significant effect on the pore structure of activated carbon produced, however, the pore characteristic of carbon changes significantly with impregnation ratio and carbonization temperature. The maximum surface area and pore volume were obtained at impregnation ratio 5:2 and carbonization temperature 750 degrees C.

  3. Land Surface Processes Simulation Over Thar Desert in Northwest India

    NASA Astrophysics Data System (ADS)

    Raja, P.; Srinivas, C. V.; Hari Prasad, K. B. R. R.; Singh, Nilendu

    2016-06-01

    Land surface processes in data scarce arid northwestern India and their influence on the regional climate including monsoon are now gaining enhanced scientific attention. In this work the seasonal variation of land surface parameters and surface-energy flux components over Lasiurus sindicus grassland system in Thar Desert, western India were simulated using the mesoscale WRF model. The data on surface fluxes from a micrometeorological station, and basic surface level weather data from the Central Arid Zone Research Institute's experimental field station (26o59'41″N; 71o29'10″E), Jaisalmer, were used for comparison. Simulations were made for typical fair weather days in three seasons [12-14 January (peak winter); 29-31 May (peak summer), 19-21 August (monsoon)] during 2012. Sensitivity experiments conducted using a 5-layer soil thermal diffusion (5TD) scheme and a comprehensive land surface physics scheme (Noah) revealed the 5TD scheme gives large biases in surface fluxes and other land surface parameters. Simulations show large variations in surface fluxes and meteorological parameters in different seasons with high friction velocities, sensible heat fluxes, deep boundary layers in summer and monsoon season as compared to winter. The shortwave radiation is underestimated during the monsoon season, and is overestimated in winter and summer. In general, the model simulated a cold bias in soil temperature in summer and monsoon season and a warm bias in winter; the simulated surface fluxes and air temperature followed these trends. These biases could be due to a negative bias in net radiation resulting from a high bias in downward shortwave radiation in various seasons. The Noah LSM simulated various parameters more realistically in all seasons than the 5TD soil scheme due to inclusion of explicit vegetation processes in the former. The differences in the simulated fluxes with the two LSMs are small in winter and large in summer. The deep mixed layers are

  4. Process for preparing active oxide powders

    DOEpatents

    Berard, Michael F.; Hunter, Jr., Orville; Shiers, Loren E.; Dole, Stephen L.; Scheidecker, Ralph W.

    1979-02-20

    An improved process for preparing active oxide powders in which cation hydroxide gels, prepared in the conventional manner are chemically dried by alternately washing the gels with a liquid organic compound having polar characteristics and a liquid organic compound having nonpolar characteristics until the mechanical water is removed from the gel. The water-free cation hydroxide is then contacted with a final liquid organic wash to remove the previous organic wash and speed drying. The dried hydroxide treated in the conventional manner will form a highly sinterable active oxide powder.

  5. Inhibitors for Androgen Receptor Activation Surfaces

    DTIC Science & Technology

    2007-09-01

    new class of chemical therapeutics for treatment of prostate cancer. 15. SUBJECT TERMS X-ray crystallography, high throughput screening, medicinal... treatments because anti-androgen resis- tance usually develops. We conducted functional and x-ray screens to identify compounds that bind the AR surface and...possibility that such compounds could be used for prostate cancer treatment . It is unlikely that natural T3 or Triac concentrations approach levels required

  6. Estimation of photosynthetically active radiation absorbed at the surface

    NASA Astrophysics Data System (ADS)

    Li, Zhanqing; Moreau, Louis; Cihlar, Josef

    1997-12-01

    This paper presents a validation and application of an algorithm by Li and Moreau [1996] for retrieving photosynthetically active radiation (PAR) absorbed at the surface (APARSFC). APARSFC is a key input to estimating PAR absorbed by the green canopy during photosynthesis. Extensive ground-based and space-borne observations collected during the BOREAS experiment in 1994 were processed, colocated, and analyzed. They include downwelling and upwelling PAR observed at three flux towers, aerosol optical depth from ground-based photometers, and satellite reflectance measurements at the top of the atmosphere. The effects of three-dimensional clouds, aerosols, and bidirectional dependence on the retrieval of APARSFC were examined. While the algorithm is simple and has only three input parameters, the comparison between observed and estimated APARSFC shows a small bias error (<10 W m-2) and moderate random error (36 W m-2 for clear, 61 W m-2 for cloudy). Temporal and/or spatial mismatch between satellite and surface observations is a major cause of the random error, especially when broken clouds are present. The algorithm was subsequently employed to map the distribution of monthly mean APARSFC over the 1000×1000 km2 BOREAS region. Considerable spatial variation is found due to variable cloudiness, forest fires, and nonuniform surface albedo.

  7. One-step electrodeposition process to fabricate cathodic superhydrophobic surface

    NASA Astrophysics Data System (ADS)

    Chen, Zhi; Li, Feng; Hao, Limei; Chen, Anqi; Kong, Youchao

    2011-12-01

    In this work, a rapid one-step process is developed to fabricate superhydrophobic cathodic surface by electrodepositing copper plate in an electrolyte solution containing manganese chloride (MnCl2·4H2O), myristic acid (CH3(CH2)12COOH) and ethanol. The superhydrophobic surfaces were characterized by means of scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The shortest electrolysis time for fabricating a superhydrophobic surface is about 1 min, the measured maximum contact angle is 163° and rolling angle is less than 3°. Furthermore, this method can be easily extended to other conductive materials. The approach is time-saving and cheap, and it is supposed to have a promising future in industrial fields.

  8. Active voltammetric microsensors with neural signal processing.

    SciTech Connect

    Vogt, M. C.

    1998-12-11

    Many industrial and environmental processes, including bioremediation, would benefit from the feedback and control information provided by a local multi-analyte chemical sensor. For most processes, such a sensor would need to be rugged enough to be placed in situ for long-term remote monitoring, and inexpensive enough to be fielded in useful numbers. The multi-analyte capability is difficult to obtain from common passive sensors, but can be provided by an active device that produces a spectrum-type response. Such new active gas microsensor technology has been developed at Argonne National Laboratory. The technology couples an electrocatalytic ceramic-metallic (cermet) microsensor with a voltammetric measurement technique and advanced neural signal processing. It has been demonstrated to be flexible, rugged, and very economical to produce and deploy. Both narrow interest detectors and wide spectrum instruments have been developed around this technology. Much of this technology's strength lies in the active measurement technique employed. The technique involves applying voltammetry to a miniature electrocatalytic cell to produce unique chemical ''signatures'' from the analytes. These signatures are processed with neural pattern recognition algorithms to identify and quantify the components in the analyte. The neural signal processing allows for innovative sampling and analysis strategies to be employed with the microsensor. In most situations, the whole response signature from the voltammogram can be used to identify, classify, and quantify an analyte, without dissecting it into component parts. This allows an instrument to be calibrated once for a specific gas or mixture of gases by simple exposure to a multi-component standard rather than by a series of individual gases. The sampled unknown analytes can vary in composition or in concentration, the calibration, sensing, and processing methods of these active voltammetric microsensors can detect, recognize, and

  9. Mechanical and tribological properties of ion beam-processed surfaces

    SciTech Connect

    Kodali, Padma

    1998-01-01

    The intent of this work was to broaden the applications of well-established surface modification techniques and to elucidate the various wear mechanisms that occur in sliding contact of ion-beam processed surfaces. The investigation included characterization and evaluation of coatings and modified surfaces synthesized by three surface engineering methods; namely, beam-line ion implantation, plasma-source ion implantation, and DC magnetron sputtering. Correlation among measured properties such as surface hardness, fracture toughness, and wear behavior was also examined. This dissertation focused on the following areas of research: (1) investigating the mechanical and tribological properties of mixed implantation of carbon and nitrogen into single crystal silicon by beam-line implantation; (2) characterizing the mechanical and tribological properties of diamond-like carbon (DLC) coatings processed by plasma source ion implantation; and (3) developing and evaluating metastable boron-carbon-nitrogen (BCN) compound coatings for mechanical and tribological properties. The surface hardness of a mixed carbon-nitrogen implant sample improved significantly compared to the unimplanted sample. However, the enhancement in the wear factor of this sample was found to be less significant than carbon-implanted samples. The presence of nitrogen might be responsible for the degraded wear behavior since nitrogen-implantation alone resulted in no improvement in the wear factor. DLC coatings have low friction, low wear factor, and high hardness. The fracture toughness of DLC coatings has been estimated for the first time. The wear mechanism in DLC coatings investigated with a ruby slider under a contact stress of 1 GPa was determined to be plastic deformation. The preliminary data on metastable BCN compound coatings indicated high friction, low wear factor, and high hardness.

  10. Publications of the Western Earth Surface Processes Team 2006

    USGS Publications Warehouse

    Powell, Charles L.; Stone, Paul

    2007-01-01

    The Western Earth Surface Processes Team (WESPT) of the U.S. Geological Survey (USGS) conducts geologic mapping, earth-surface process investigations, and related topical earth science studies in the western United States. This work is focused on areas where modern geologic maps and associated earth-science data are needed to address key societal and environmental issues such as ground-water quality, landslides and other potential geologic hazards, and land-use decisions. Areas of primary emphasis in 2006 included southern California, the San Francisco Bay region, the Mojave Desert, the Colorado Plateau region of northern Arizona, and the Pacific Northwest. The team has its headquarters in Menlo Park, California, and maintains smaller field offices at several other locations in the western United States. This compilation gives the bibliographical citations for 123 new publications, most of which are available online using the hyperlinks provided.

  11. APOLLO 10: Training for Lunar Surface Activities

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Astronauts train on a mock-up lunar surface, practicing the procedures they will follow on the real thing, and adjusting to the demands of the workload. From the film documentary 'APOLLO 10: 'Green Light for a Lunar Landing''. Part of a documentary series made in the early 70's on the APOLLO missions, and narrated by Burgess Meredith. (Actual date created is not known at this time) APOLLO 10: Manned lunar orbital flight with Thomas P Stafford, John W. Young, and Eugene A. Cernan to test all aspects of an actual manned lunar landing except the landing. Mission Duration 192hrs 3mins 23 sec

  12. The Land Processes Distributed Active Archive Center (LP DAAC)

    USGS Publications Warehouse

    Golon, Danielle K.

    2016-10-03

    The Land Processes Distributed Active Archive Center (LP DAAC) operates as a partnership with the U.S. Geological Survey and is 1 of 12 DAACs within the National Aeronautics and Space Administration (NASA) Earth Observing System Data and Information System (EOSDIS). The LP DAAC ingests, archives, processes, and distributes NASA Earth science remote sensing data. These data are provided to the public at no charge. Data distributed by the LP DAAC provide information about Earth’s surface from daily to yearly intervals and at 15 to 5,600 meter spatial resolution. Data provided by the LP DAAC can be used to study changes in agriculture, vegetation, ecosystems, elevation, and much more. The LP DAAC provides several ways to access, process, and interact with these data. In addition, the LP DAAC is actively archiving new datasets to provide users with a variety of data to study the Earth.

  13. Proteolytic Processing Regulates Placental Growth Factor Activities*

    PubMed Central

    Hoffmann, Daniel C.; Willenborg, Sebastian; Koch, Manuel; Zwolanek, Daniela; Müller, Stefan; Becker, Ann-Kathrin A.; Metzger, Stephanie; Ehrbar, Martin; Kurschat, Peter; Hellmich, Martin; Hubbell, Jeffrey A.; Eming, Sabine A.

    2013-01-01

    Placental growth factor (PlGF) is a critical mediator of blood vessel formation, yet mechanisms of its action and regulation are incompletely understood. Here we demonstrate that proteolytic processing regulates the biological activity of PlGF. Specifically, we show that plasmin processing of PlGF-2 yields a protease-resistant core fragment comprising the vascular endothelial growth factor receptor-1 binding site but lacking the carboxyl-terminal domain encoding the heparin-binding domain and an 8-amino acid peptide encoded by exon 7. We have identified plasmin cleavage sites, generated a truncated PlGF118 isoform mimicking plasmin-processed PlGF, and explored its biological function in comparison with that of PlGF-1 and -2. The angiogenic responses induced by the diverse PlGF forms were distinct. Whereas PlGF-2 increased endothelial cell chemotaxis, vascular sprouting, and granulation tissue formation upon skin injury, these activities were abrogated following plasmin digestion. Investigation of PlGF/Neuropilin-1 binding and function suggests a critical role for heparin-binding domain/Neuropilin-1 interaction and its regulation by plasmin processing. Collectively, here we provide new mechanistic insights into the regulation of PlGF-2/Neuropilin-1-mediated tissue vascularization and growth. PMID:23645683

  14. Activation of consolidation processes of alumina ceramics

    NASA Astrophysics Data System (ADS)

    Matrenin, S. V.; Zenin, B. S.; Tayukin, R. V.

    2016-02-01

    The methods for activating sintering ceramics based on Al2O3 by mechanical activation in the planetary mill, by adding in the mixture of nanopowders (NP) Al, Al2O3, and submicron powder TiO2, and by applying the technology of spark plasma sintering (SPS) are developed. It has been shown that adding the nanopowder up to 20 wt. % Al2O3 in a coarse powder α-Al2O3 activates the sintering process resulting in increased density and hardness of the sintered alumina ceramics. Substantial effect of increasing density of alumina ceramics due to adding the submicron powder TiO2 in the compound of initial powder mixtures has been established.

  15. Probing Interfacial Processes on Graphene Surface by Mass Detection

    NASA Astrophysics Data System (ADS)

    Kakenov, Nurbek; Kocabas, Coskun

    2013-03-01

    In this work we studied the mass density of graphene, probed interfacial processes on graphene surface and examined the formation of graphene oxide by mass detection. The graphene layers were synthesized by chemical vapor deposition method on copper foils and transfer-printed on a quartz crystal microbalance (QCM). The mass density of single layer graphene was measured by investigating the mechanical resonance of the QCM. Moreover, we extended the developed technique to probe the binding dynamics of proteins on the surface of graphene, were able to obtain nonspecific binding constant of BSA protein of graphene surface in aqueous solution. The time trace of resonance signal showed that the BSA molecules rapidly saturated by filling the available binding sites on graphene surface. Furthermore, we monitored oxidation of graphene surface under oxygen plasma by tracing the changes of interfacial mass of the graphene controlled by the shifts in Raman spectra. Three regimes were observed the formation of graphene oxide which increases the interfacial mass, the release of carbon dioxide and the removal of small graphene/graphene oxide flakes. Scientific and Technological Research Council of Turkey (TUBITAK) grant no. 110T304, 109T209, Marie Curie International Reintegration Grant (IRG) grant no 256458, Turkish Academy of Science (TUBA-Gebip).

  16. Free surface BCP self-assembly process characterization with CDSEM

    NASA Astrophysics Data System (ADS)

    Levi, Shimon; Weinberg, Yakov; Adan, Ofer; Klinov, Michael; Argoud, Maxime; Claveau, Guillaume; Tiron, Raluca

    2016-03-01

    A simple and common practice to evaluate Block copolymers (BCP) self-assembly performances, is on a free surface wafer. With no guiding pattern the BCP designed to form line space pattern for example, spontaneously rearranges to form a random fingerprint type of a pattern. The nature of the rearrangement is dictated by the physical properties of the BCP moieties, wafer surface treatment and the self-assembly process parameters. Traditional CDSEM metrology algorithms are designed to measure pattern with predefined structure, like linespace or oval via holes. Measurement of pattern with expected geometry can reduce measurement uncertainty. Fingerprint type of structure explored in this dissertation, poses a challenge for CD-SEM measurement uncertainty and offers an opportunity to explore 2D metrology capabilities. To measure this fingerprints we developed a new metrology approach that combines image segmentation and edge detection to measure 2D pattern with arbitrary rearrangement. The segmentation approach enabled to quantify the quality of the BCP material and process, detecting 2D attributes such as: CD and CDU at one axis, and number of intersections, length and number of PS fragments, etched PMMA spaces and donut shapes numbers on the second axis. In this paper we propose a 2D metrology to measure arbitrary BCP pattern on a free surface wafer. We demonstrate experimental results demonstrating precision data, and characterization of PS-b-PMMA BCP, intrinsic period L0 = 38nm (Arkema), processed at different bake time and temperatures.

  17. Exposing earth surface process model simulations to a large audience

    NASA Astrophysics Data System (ADS)

    Overeem, I.; Kettner, A. J.; Borkowski, L.; Russell, E. L.; Peddicord, H.

    2015-12-01

    The Community Surface Dynamics Modeling System (CSDMS) represents a diverse group of >1300 scientists who develop and apply numerical models to better understand the Earth's surface. CSDMS has a mandate to make the public more aware of model capabilities and therefore started sharing state-of-the-art surface process modeling results with large audiences. One platform to reach audiences outside the science community is through museum displays on 'Science on a Sphere' (SOS). Developed by NOAA, SOS is a giant globe, linked with computers and multiple projectors and can display data and animations on a sphere. CSDMS has developed and contributed model simulation datasets for the SOS system since 2014, including hydrological processes, coastal processes, and human interactions with the environment. Model simulations of a hydrological and sediment transport model (WBM-SED) illustrate global river discharge patterns. WAVEWATCH III simulations have been specifically processed to show the impacts of hurricanes on ocean waves, with focus on hurricane Katrina and super storm Sandy. A large world dataset of dams built over the last two centuries gives an impression of the profound influence of humans on water management. Given the exposure of SOS, CSDMS aims to contribute at least 2 model datasets a year, and will soon provide displays of global river sediment fluxes and changes of the sea ice free season along the Arctic coast. Over 100 facilities worldwide show these numerical model displays to an estimated 33 million people every year. Datasets storyboards, and teacher follow-up materials associated with the simulations, are developed to address common core science K-12 standards. CSDMS dataset documentation aims to make people aware of the fact that they look at numerical model results, that underlying models have inherent assumptions and simplifications, and that limitations are known. CSDMS contributions aim to familiarize large audiences with the use of numerical

  18. Surface diffusion activation energy determination using ion beam microtexturing

    NASA Technical Reports Server (NTRS)

    Rossnagel, S. M.; Robinson, R. S.

    1982-01-01

    The activation energy for impurity atom (adatom) surface diffusion can be determined from the temperature dependence of the spacing of sputter cones. These cones are formed on the surface during sputtering while simultaneously adding impurities. The impurities form clusters by means of surface diffusion, and these clusters in turn initiate cone formation. Values are given for the surface diffusion activation energies for various materials on polycrystalline Cu, Al, Pb, Au, and Ni. The values for different impurity species on each of these substrates are approximately independent of impurity species within the experimental uncertainty, suggesting the absence of strong chemical bonding effects on the diffusion.

  19. Surfaces of Fluorinated Pyridinium Block Copolymers with Enhanced Antibacterial Activity

    SciTech Connect

    Krishnan,S.; Ward, R.; Hexemer, A.; Sohn, K.; Lee, K.; Angert, E.; Fischer, D.; Kramer, E.; Ober, C.

    2006-01-01

    Polystyrene-b-poly(4-vinylpyridine) copolymers were quaternized with 1-bromohexane and 6-perfluorooctyl-1-bromohexane. Surfaces prepared from these polymers were characterized by contact angle measurements, near-edge X-ray absorption fine structure spectroscopy and X-ray photoelectron spectroscopy. The fluorinated pyridinium surfaces showed enhanced antibacterial activity compared to their nonfluorinated counterparts. Even a polymer with a relatively low molecular weight pyridinium block showed high antimicrobial activity. The bactericidal effect was found to be related to the molecular composition and organization in the top 2-3 nm of the surface and increased with increasing hydrophilicity and pyridinium concentration of the surface.

  20. Hemagglutinating activity in phytopathogenic bacteria surface compounds.

    PubMed

    Serra, M T; Castresana, M C; Tejerina, G

    1987-01-01

    Extracellular components of plant pathogenic bacteria were obtained from their culture medium as well as from the whole cells by using NaCl 1 M, pH 6.0; 20% sucrose dissolved in 0.03 M Tris buffer, pH 8.0; or 0.05 M Na2EDTA. All the extracts from Erwinia carotovora subsp. carotovora, Xanthomonas campestris pv. campestris, Pseudomonas syringae pv. phaseolicola, Xanthomonas campestris pv. phaseoli, Pseudomonas solanacearum, and Erwinia carotovora subsp. atroseptica, were assayed for hemagglutinating activity on sheep, rabbit and chicken red blood cells (RBCs). The only active extracts were those obtained by NaCl treatment. They agglutinated sheep and rabbit erythrocytes. Extracts from E. carotovora subsp. atroseptica gave rise to the high agglutination titer on rabbit RBCs. These extracts had the lowest polysaccharide/protein ratio. E. carotovora subsp. carotovora extracts showed only a low titer (18.5 units). The agglutinating activity present in NaCl extracts of the bacteria tested was inhibited by different carbohydrates to various extent. Extracts from E. carotovora subsp. atroseptica appeared to be the most sensitive ones while those of E. carotovora subsp. carotovora least sensitive to the presence of sugar. It is suggested that hemagglutinins observed in plant pathogenic bacteria and those in plant host are similar and that both may, in some way, be involved in the plant-parasite relationship.

  1. Process optimization of mechano-electrospinning by response surface methodology.

    PubMed

    Bu, Ningbin; Huang, YongAn; Duan, Yongqing; Yin, Zhouping

    2014-05-01

    In this paper, mechano-electrospinning (MES) is presented to write the polyvinylidene fluoride (PVDF) solution into fibers directly, and the effects of the process parameters on the fiber are investigated experimentally based on response surface methodology. The different width of the fiber is obtained by adjusting the individual process parameters (velocity of the substrate, applied voltage and nozzle-to-substrate distance). Considering the continuous jet and stable Taylor-cone, the operation field is selected for investigating the complicated relationship between the process parameters on the width of the fiber by using the response surface methodology. The experiment results show that the predicted width of the fiber is in good agreement with the actual width of the fiber. Based on the analysis of the importance of the terms in the equation, a simple model can be used to predict the width of the fiber. Depending on this model, a large number of calibration experiments can be subducted. Additionally, the principle of the selection of the process parameters is presented by optimizing parameters, which can give a guideline for obtaining the desired fiber in the experiment.

  2. Modeling of an Active Tablet Coating Process.

    PubMed

    Toschkoff, Gregor; Just, Sarah; Knop, Klaus; Kleinebudde, Peter; Funke, Adrian; Djuric, Dejan; Scharrer, Georg; Khinast, Johannes G

    2015-12-01

    Tablet coating is a common unit operation in the pharmaceutical industry, during which a coating layer is applied to tablet cores. The coating uniformity of tablets in a batch is especially critical for active coating, that is, coating that contains an active pharmaceutical ingredient. In recent years, discrete element method (DEM) simulations became increasingly common for investigating tablet coating. In this work, DEM was applied to model an active coating process as closely as possible, using measured model parameters and non-spherical particles. We studied how operational conditions (rotation speed, fill level, number of nozzles, and spray rate) influence the coating uniformity. To this end, simulation runs were planned and interpreted according to a statistical design of (simulation) experiments. Our general goal was to achieve a deeper understanding of the process in terms of residence times and dimensionless scaling laws. With that regard, the results were interpreted in light of analytical models. The results were presented at various detail levels, ranging from an overview of all variations to in-depth considerations. It was determined that the biggest uniformity improvement in a realistic setting was achieved by increasing the number of spray nozzles, followed by increasing the rotation speed and decreasing the fill level.

  3. Active PZT fibers: a commercial production process

    NASA Astrophysics Data System (ADS)

    Strock, Harold B.; Pascucci, Marina R.; Parish, Mark V.; Bent, Aaron A.; Shrout, Thomas R.

    1999-07-01

    Lead Zirconate Titanate (PZT) active fibers, from 80 to 250 micrometers in diameter, are produced for the AFOSR/DARPA funded Active Fiber Composites Consortium (AFCC) Program and commercial customers. CeraNova has developed a proprietary ceramics-based technology to produce PZT mono-filaments of the required purity, composition, straightness, and piezoelectric properties for use in active fiber composite structures. CeraNova's process begins with the extrusion of continuous lengths of mono-filament precursor fiber from a plasticized mix of PZT-5A powder. The care that must be taken to avoid mix contamination is described using illustrations form problems experiences with extruder wear and metallic contamination. Corrective actions are described and example microstructures are shown. The consequences of inadequate lead control are also shown. Sintered mono- filament mechanical strength and piezoelectric properties data approach bulk values but the validity of such a benchmark is questioned based on variable correlation with composite performance measures. Comb-like ceramic preform structures are shown that are being developed to minimize process and handling costs while maintaining the required mono-filament straightness necessary for composite fabrication. Lastly, actuation performance data are presented for composite structures fabricated and tested by Continuum Control Corporation. Free strain actuation in excess of 2000 microstrain are observed.

  4. Characterization of the surface changes during the activation of erbium/erbium oxide for hydrogen storage.

    SciTech Connect

    Zavadil, Kevin Robert; Snow, Clark Sheldon; Brumbach, Michael Todd

    2010-09-01

    Erbium is known to effectively load with hydrogen when held at high temperature in a hydrogen atmosphere. To make the storage of hydrogen kinetically feasible, a thermal activation step is required. Activation is a routine practice, but very little is known about the physical, chemical, and/or electronic processes that occur during Activation. This work presents in situ characterization of erbium Activation using variable energy photoelectron spectroscopy at various stages of the Activation process. Modification of the passive surface oxide plays a significant role in Activation. The chemical and electronic changes observed from core-level and valence band spectra will be discussed along with corroborating ion scattering spectroscopy measurements.

  5. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

    1986-10-07

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

  6. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

    1986-01-01

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

  7. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, G.G.; Kato, T.R.; Schonegg, E.

    1985-04-11

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed. 5 tabs.

  8. N-Glycosylation Regulates ADAM8 Processing and Activation*

    PubMed Central

    Srinivasan, Srimathi; Romagnoli, Mathilde; Bohm, Andrew; Sonenshein, Gail E.

    2014-01-01

    The transmembrane ADAM8 (A Disintegrin And Metalloproteinase 8) protein is abundantly expressed in human breast tumors and derived metastases compared with normal breast tissue, and plays critical roles in aggressive Triple-Negative breast cancers (TNBCs). During ADAM8 maturation, the inactive proform dimerizes or multimerizes and autocatalytically removes the prodomain leading to the formation of the active, processed form. ADAM8 is a glycoprotein; however, little was known about the structure or functional role of these sugar moieties. Here, we report that in estrogen receptor (ER)α-negative, but not -positive, breast cancer cells ADAM8 contains N-glycosylation, which is required for its correct processing and activation. Consistently ADAM8 dimers were detected on the surface of ERα-negative breast cancer cells but not on ERα-positive ones. Site-directed mutagenesis confirmed four N-glycosylazhytion sites (Asn-67, Asn-91, Asn-436, and Asn-612) in human ADAM8. The Asn-67 and Asn-91 prodomain sites contained high mannose, whereas complex type N-glycosylation was observed on Asn-436 and Asn-612 in the active and remnant forms. The Asn-91 and Asn-612 sites were essential for its correct processing and cell surface localization, in particular its exit from the Golgi and endoplasmic reticulum, respectively. The N436Q mutation led to decreased ADAM8 stability due to enhanced lysosomal degradation. In contrast, mutation of the Asn-67 site had only modest effects on enzyme stability and processing. Thus, N-glycosylation is essential for processing, localization, stability, and activity of ADAM8. PMID:25336660

  9. Influence of surface coverage on the chemical desorption process

    SciTech Connect

    Minissale, M.; Dulieu, F.

    2014-07-07

    In cold astrophysical environments, some molecules are observed in the gas phase whereas they should have been depleted, frozen on dust grains. In order to solve this problem, astrochemists have proposed that a fraction of molecules synthesized on the surface of dust grains could desorb just after their formation. Recently the chemical desorption process has been demonstrated experimentally, but the key parameters at play have not yet been fully understood. In this article, we propose a new procedure to analyze the ratio of di-oxygen and ozone synthesized after O atoms adsorption on oxidized graphite. We demonstrate that the chemical desorption efficiency of the two reaction paths (O+O and O+O{sub 2}) is different by one order of magnitude. We show the importance of the surface coverage: for the O+O reaction, the chemical desorption efficiency is close to 80% at zero coverage and tends to zero at one monolayer coverage. The coverage dependence of O+O chemical desorption is proved by varying the amount of pre-adsorbed N{sub 2} on the substrate from 0 to 1.5 ML. Finally, we discuss the relevance of the different physical parameters that could play a role in the chemical desorption process: binding energy, enthalpy of formation, and energy transfer from the new molecule to the surface or to other adsorbates.

  10. Mineralization at Titanium Surfaces is a Two-Step Process

    PubMed Central

    Nygren, Håkan; Ilver, Lars; Malmberg, Per

    2016-01-01

    Mapping the initial reaction of implants with blood or cell culture medium is important for the understanding of the healing process in bone. In the present study, the formation of low crystalline carbonated hydroxyapatite (CHA) onto commercially pure titanium (Ti) implants from cell culture medium and blood, is described as an early event in bone healing at implants. The Ti-implants were incubated with cell culture medium (DMEM) or whole blood and the surface concentration of Ca, P and HA was analyzed by XPS, EDX and Tof-SIMS. After incubation with DMEM for 16 h and 72 h, EDX and XPS analysis showed stable levels of Ca and P on the Ti-surface. ESEM images showed an even distribution of Ca and P. Further analysis of the XPS results indicated that CHA was formed at the implants. Analysis with ToF-SIMS yielded high m.w. fragments of HA, such as Ca2PO4 at m/z 174.9 and Ca3PO5 at m/z 230.8, as secondary ions at the Ti-surfaces. Analysis of implants incubated in blood for 16 h, with ToF-SIMS, showed initial formation of CHA yielding CaOH as secondary ion. The results indicate that early mineralization at Ti-surfaces is an important step in the healing of implants into bone. PMID:26999231

  11. Elementary surface processes during reactive magnetron sputtering of chromium

    SciTech Connect

    Monje, Sascha; Corbella, Carles Keudell, Achim von

    2015-10-07

    The elementary surface processes occurring on chromium targets exposed to reactive plasmas have been mimicked in beam experiments by using quantified fluxes of Ar ions (400–800 eV) and oxygen atoms and molecules. For this, quartz crystal microbalances were previously coated with Cr thin films by means of high-power pulsed magnetron sputtering. The measured growth and etching rates were fitted by flux balance equations, which provided sputter yields of around 0.05 for the compound phase and a sticking coefficient of O{sub 2} of 0.38 on the bare Cr surface. Further fitted parameters were the oxygen implantation efficiency and the density of oxidation sites at the surface. The increase in site density with a factor 4 at early phases of reactive sputtering is identified as a relevant mechanism of Cr oxidation. This ion-enhanced oxygen uptake can be attributed to Cr surface roughening and knock-on implantation of oxygen atoms deeper into the target. This work, besides providing fundamental data to control oxidation state of Cr targets, shows that the extended Berg's model constitutes a robust set of rate equations suitable to describe reactive magnetron sputtering of metals.

  12. Diagnostics of plasma-surface interactions in plasma processes

    NASA Astrophysics Data System (ADS)

    Ishikawa, Kenji

    2014-10-01

    Low temperature plasma including electrons, ions, radicals and photons can be applied because only high temperature of electron but for background gases. Recently plasma applications in biology and medicine have grown significantly. For complexity of mechanisms, it is needed to understand comprehensively the plasma-surface interactions. To diagnose the interactions comprises of three areas; (1) incident species generated in plasmas toward the surface, (2) surface reactions such as scission and bond of chemical bonds, and (3) products after the reactions. Considered with non-linearity of the chemical reactions as changed by an initial state, we have focused and developed to observe dangling bonds in situ at real time by electron spin resonance (ESR). Moreover, individual contribution and simultaneous irradiation of each species such as radicals and photons have been studied in utilization of light shades and windows in similar manner of the pellets for plasma process evaluation (PAPE). As exampled, the interaction of polymeric materials, fungal spores and edible meats with plasmas were studied on the basis of the real time in situ observations of dangling bonds or surface radicals formation.

  13. Energy transfer process between exciton and surface plasmon: Complete transition from Forster to surface energy transfer

    NASA Astrophysics Data System (ADS)

    Kumar, Arunandan; Tyagi, Priyanka; Srivastava, Ritu; Mehta, D. S.; Kamalasanan, M. N.

    2013-05-01

    The energy transfer process between surface plasmons and excitons was studied by varying the filling fraction of gold (Au) nano-clusters (NCs) and by placing a spacer of different thickness between Au NC and organic semiconductor layer. The intensity enhancement has occurred for 10%-50% filling fractions and 4-14 nm spacer thicknesses. Energy transfer mechanism was found to switch from Forster type to surface type by increase in filling fraction. Transverse electric field for Au NCs was simulated and we observed that for filling fraction <30%, Au NCs behave like 1-dimensional dipole and for >60%, they behave like 2-dimensional dipoles.

  14. Laser processing of metallic biomaterials: An approach for surface patterning and wettability control

    NASA Astrophysics Data System (ADS)

    Razi, Sepehr; Mollabashi, Mahmoud; Madanipour, Khosro

    2015-12-01

    Q -switched Nd:YAG laser is used to manipulate the surface morphology and wettability characteristic of 316L stainless steel (SS) and titanium biomaterials. Water and glycerol are selected as wettability testing liquids and the sessile drop method is used for the contact angle measurements. Results indicate that on both of the metals, wettability toward water improves significantly after the laser treatment. Different analyses including the study of the surface morphology, free energy and oxidation are assessed in correlation with wettability. Beside the important role of the laser-induced surface patterns, the increase in the surface roughness, oxygen content and the polar component of the surface energy, are detected as the most important physical and chemical phenomena controlling the improvement in the wettability. However, all the processed hydrophilic surfaces that are exposed to air become hydrophobic over time. The time dependency of the surface wettability is related to the chemical activities on the treated surfaces and the reduction of oxygen/carbon (O/C) ratio on them. The behavior is further studied with investigating the effect of the keeping environment and changes of the components of the surface tension. Results show that the pulsed laser treatment is a versatile approach to create either hydrophobic or super hydrophilic surfaces for industrial and medical applications.

  15. Surface hardening of two cast irons by friction stir processing

    NASA Astrophysics Data System (ADS)

    Fujii, Hidetoshi; Yamaguchi, Yasufumi; Kikuchi, Toshifumi; Kiguchi, Shoji; Nogi, Kiyoshi

    2009-05-01

    The Friction Stir Processing (FSP) was applied to the surface hardening of cast irons. Flake graphite cast iron (FC300) and nodular graphite cast iron (FCD700) were used to investigate the validity of this method. The matrices of the FC300 and FC700 cast irons are pearlite. The rotary tool is a 25mm diameter cylindrical tool, and the travelling speed was varied between 50 and 150mm/min in order to control the heat input at the constant rotation speed of 900rpm. As a result, it has been clarified that a Vickers hardness of about 700HV is obtained for both cast irons. It is considered that a very fine martensite structure is formed because the FSP generates the heat very locally, and a very high cooling rate is constantly obtained. When a tool without an umbo (probe) is used, the domain in which graphite is crushed and striated is minimized. This leads to obtaining a much harder sample. The hardness change depends on the size of the martensite, which can be controlled by the process conditions, such as the tool traveling speed and the load. Based on these results, it was clarified that the FSP has many advantages for cast irons, such as a higher hardness and lower distortion. As a result, no post surface heat treatment and no post machining are required to obtain the required hardness, while these processes are generally required when using the traditional methods.

  16. The use of hyperspectral / directional data in land surface process models

    NASA Astrophysics Data System (ADS)

    Mauser, W.; Schneider, K.; Bach, H.

    2002-06-01

    The presentation analyses the role of land surface parameters, in particular those, which can be derived from hyperspectral/directional remote sensing data, for land surface process models. Land surface process models are used to understand and predict the dominant cycles of energy, water, carbon, nutrients and humans on the plant on the local, regional and global scale. They address environmental issues of great importance like the carbon budget and the availability and quality of water as a basis for life. Land surface process models use land surface parameters to characterize the properties of the land surface and to solve the underlying physically based models. Among these parameters are vegetation type, leaf area index (LAI), fraction of absorbed photosynthetically active solar radiation, biomass, soilmoisture or chlorophyll-content. The main characteristics of the cycles on the land surface are complexity as well as large temporal dynamics and spatial heterogeneity on all considered scales. Conventional, state of the art modelling of land surface processes usually derive the temporal and spatial distribution of the parameters involved from interpolation of point measurements, which either leads to large errors or creates prohibitive sampling efforts. Recently land surface process models have learned to treat spatial processes in a spatial way and are now prepared to digest spatially explicit input information e.g. from remote sensing soruces. Remote Sensing data and especially hyperspectral/directional data can be used to derive land surface parameters. Their main advantage for land surface process modelling is, that they can implicitly measure the temporal dynamics and spatial heterogeneity of the reflection of the land surface. Parameter models convert the directional reflectance spectra into spatial fields of land surface parameter values. They in turn can be used as spatially distributed inputs to the process models. In the classical approach (and usually

  17. Surface-active properties of humic and sulfochlorohumic acids

    SciTech Connect

    Ryabova, I.N.; Mustafina, G.A.; Akkulova, Z.G.; Satymbaeva, A.S.

    2009-10-15

    The surface tension of alkaline solutions of humic acids and their sulfochloroderivatives, which are synthesized by sulfonation of chlorohumic acids isolated from coal chlorinated by the electrochemical method, is investigated. It is established that humic compounds possess weak surface activity. Basic adsorption parameters are calculated.

  18. Characterization of surface active materials derived from farm products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface active materials obtained by chemical modification of plant protein isolates (lupin, barley, oat), corn starches (dextrin, normal, high amylose, and waxy) and soybean oil (soybean oil based polysoaps, SOPS) were investigated for their surface and interfacial properties using axisymmetric dro...

  19. Howardite Noble Gases as Indicators of Asteroid Surface Processing

    NASA Technical Reports Server (NTRS)

    Cartwright, J. A.; Mittlefehldt, D. W.; Herrin, J. S.; Ott, U.

    2011-01-01

    The HED (Howardite, Eucrite and Diogenite) group meteorites likely or iginate from the Asteroid 4 Vesta - one of two asteroid targets of NA SA's Dawn mission. Whilst Howardites are polymict breccias of eucriti c and diogenitic material that often contain "regolithic" petrologica l features, neither their exact regolithic nature nor their formation processes are well defined. As the Solar Wind (SW) noble gas compon ent is implanted onto surfaces of solar system bodies, noble gas anal yses of Howardites provides a key indicator of regolithic origin. In addition to SW, previous work by suggested that restricted Ni (300-12 00 micro g/g) and Al2O3 (8-9 wt%) contents may indicate an ancient we ll-mixed regolith. Our research combines petrological, compositional and noble gas analyses to help improve understanding of asteroid reg olith formation processes, which will play an intergral part in the i nterpretation of Dawn mission data. Following compositional and petrological analyses, we developed a regolith grading scheme for our sampl e set of 30 Howardites and polymict Eucrites. In order to test the r egolith indicators suggested by, our 8 selected samples exhibited a r ange of Ni, Al2O3 contents and regolithic grades. Noble gas analyses were performed using furnace stepheating on our MAP 215-50 noble gas mass spectrometer. Of our 8 howardites, only 3 showed evidence of SW noble gases (e.g approaching Ne-20/Ne-22 approximately equals 13.75, Ne-21/Ne-22 approximately equals 0.033). As these samples display low regolithic grades and a range of Ni and Al2O3 contents, so far we are unable to find any correlation between these indicators and "regolit hic" origin. These results have a number of implications for both Ho wardite and Vesta formation, and may suggest complex surface stratigr aphies and surface-gardening processes.

  20. Surface activity of Corophium volutator: A role for parasites?

    NASA Astrophysics Data System (ADS)

    Damsgaard, Jacob Tørring; Mouritsen, Kim N.; Jensen, K. Thomas

    2005-08-01

    In soft-bottom intertidal habitats, the normally infaunal amphipod Corophium volutator is often found active on the sediment surface during low tide, exposed to desiccation and shorebird predation. Here we examine whether such risky behaviour is related to parasite infections. Surface-active and buried C. volutator were collected during a low tide period in the Danish Wadden Sea, and the infection patterns of the two groups were described in relation to sex and size. Surface-active males and females were more heavily infested by microphallid trematodes (four species) than buried specimens of the same sex and size class. Although the density of surfaced amphipods decreased as a function of exposure time, the mean parasite load of those that remained on the surface increased. A narrow size-specific parasite intensity threshold above which the amphipods were always surface active did not exist: heavily infected individuals were also found buried in the substrate. Although likely to be beneficial to the parasites, this suggests that the behavioural alteration is a side-effect of the infections rather than a consequence of direct parasitic manipulation. Besides the presumed mortality associated with the parasite-related surface activity in a range of size-classes, the intensity-size frequency distribution indicated that larger and hence heavily infected hosts are removed from the population. Together it demonstrates that microphallid trematodes impact the population dynamics of C. volutator.

  1. Enhancement of activated sludge disintegration and dewaterability by Fenton process

    NASA Astrophysics Data System (ADS)

    Heng, G. C.; Isa, M. H.

    2016-06-01

    Municipal and industrial wastewater treatment plants produce large amounts of sludge. This excess sludge is an inevitable drawback inherent to the activated sludge process. In this study, the waste activated sludge was obtained from the campus wastewater treatment plant at Universiti Teknologi PETRONAS (UTP), Malaysia. Fenton pretreatment was optimized by using the response surface methodology (RSM) to study the effects of three operating conditions including the dosage of H2O2 (g H2O2/kg TS), the molar ratio of H2O2/Fe2+ and reaction time. The optimum operating variables to achieve MLVSS removal 65%, CST reduction 28%, sCOD 11000 mg/L and EPS 500 mg/L were: 1000 g H2O2/kg TS, H2O2/Fe2+ molar ratio 70 and reaction time 45 min. Fenton process was proved to be able to enhance the sludge disintegration and dewaterability.

  2. Surface Modification of Nickel Foams by a Slurry Aluminizing Process

    SciTech Connect

    Omar, H.; Papanastasiou, N.; Psyllaki, P.; Stergioudi, F.; Tsipas, D. N.; Tsipas, S. A.; Michailidis, N.

    2010-01-21

    A novel slurry-based process for aluminizing nickel foams while improving the mechanical properties and conserving the excellent ductility is reported. Cellular unalloyed nickel foams with 92% porosity and uniform pore size and distribution were used as a starting material. Several slurries of different compositions were examined to investigate the possibility of developing an aluminide-nickel intermetallic coating on a Ni foam without considerably degrading the original ductile properties of the foam. The process temperature was varying from 400 to 850 deg. C and the process holding time was ranging between 2h to 6h. Scanning electron microscopy with an energy dispersive X-ray spectrometry and X-Ray diffraction were applied to assess the effectiveness of the aluminizing process and determine both the optimum parameters of the procedure (slurry composition, holding temperature and time) and the concentration profiles across the coating cross-section. The mechanical behavior of the aluminized Ni-foams was evaluated by the conduction of micro-tension tests. The resulting Ni-foams after aluminization retain the pore structure of original Ni-foams and present a thick outer surface layer which consists of a range of aluminide phases. The mechanical properties of the Ni-foams aluminized in low process temperature were insignificantly affected.

  3. Process Setting through General Linear Model and Response Surface Method

    NASA Astrophysics Data System (ADS)

    Senjuntichai, Angsumalin

    2010-10-01

    The objective of this study is to improve the efficiency of the flow-wrap packaging process in soap industry through the reduction of defectives. At the 95% confidence level, with the regression analysis, the sealing temperature, temperatures of upper and lower crimper are found to be the significant factors for the flow-wrap process with respect to the number/percentage of defectives. Twenty seven experiments have been designed and performed according to three levels of each controllable factor. With the general linear model (GLM), the suggested values for the sealing temperature, temperatures of upper and lower crimpers are 185, 85 and 85° C, respectively while the response surface method (RSM) provides the optimal process conditions at 186, 89 and 88° C. Due to different assumptions between percentage of defective and all three temperature parameters, the suggested conditions from the two methods are then slightly different. Fortunately, the estimated percentage of defectives at 5.51% under GLM process condition and the predicted percentage of defectives at 4.62% under RSM process condition are not significant different. But at 95% confidence level, the percentage of defectives under RSM condition can be much lower approximately 2.16% than those under GLM condition in accordance with wider variation. Lastly, the percentages of defectives under the conditions suggested by GLM and RSM are reduced by 55.81% and 62.95%, respectively.

  4. Land surface process and radiobrightness modeling of the Great Plains

    NASA Astrophysics Data System (ADS)

    Judge, Jasmeet

    Accurate estimation of stored water by Land Surface Process (LSP) models is crucial to the prediction of continental weather and near-term climate by General Circulation Models (GCMs). This dissertation represents an important step toward assimilating the satellite radiometric observations to improve the soil moisture estimates. It consists of "forward" modeling of terrain brightnesses through a biophysically-based Land Surface Process/Radiobrightness (LSP/R) model, and correlating ground-based brightnesses with those from the Special Sensor Microwave/Imager (SSM/I). The LSP/R model was modified and calibrated for representative terrain in the Great Plains during summertime, when the surface processes are dominant and strongly coupled. The calibration used data from two collaborative field investigations, the fourth and the fifth Radiobrightness Energy Balance Experiments (REBEX-4 and REBEX-5). REBEX-4 was a collaboration with the Atmospheric Environment Service (AES), Canada, at the USGS EROS Data Center near Sioux Falls, SD. During the experiment, we observed microwave emission and concurrent micro-meteorological parameters at a bare soil and a nearby grass site from June-September in 1996. REBEX-5 was the University of Michigan's contribution to an extensive field investigation, Southern Great Plains Hydrology Experiment (SGP'97), conducted in north central Oklahoma from June 18--July 17 in 1997. During REBEX-5, we measured brightnesses of senescent winter wheat and after harvest wheat-stubble. In general, the calibrated LSP model predicted realistic surface processes that compared well with the field observations. The model predictions were most sensitive to shortwave albedo of the terrain and soil thermal and hydraulic conductivities. The Radiobrightness module captured the mean diurnal variations in brightnesses. The H-pol terrain brightnesses at 19 GHz were more sensitive to soil moisture and roughness than the V-pol brightnesses. The comparison of the EASE

  5. MarsSI: Martian surface Data processing Application

    NASA Astrophysics Data System (ADS)

    Lozac'h, L.; Quantin-Nataf, C.; Loizeau, D.; Clenet, H.; Bultel, B.; Allemand, P.; Thollot, P.; Fernando, J.; Ody, A.; Harrison, S.

    2015-10-01

    We designed a distributed information system called MarsSI to manage orbital data from martian orbiters. The application easily and rapidly allows the user to process data from these orbiters and to download scientifically ready-to-use products of Mars surface. The application also allows DTM computation from CTX and HiRISE images. This application is open to the scientific community and can be found at this address: http://emars.univ-lyon1.fr The creation of an account is required, for that email Loïc Lozac'h : loic.lozach@univ-lyon1.fr

  6. Process of forming catalytic surfaces for wet oxidation reactions

    NASA Technical Reports Server (NTRS)

    Jagow, R. B. (Inventor)

    1977-01-01

    A wet oxidation process was developed for oxidizing waste materials, comprising dissolved ruthenium salt in a reactant feed stream containing the waste materials. The feed stream is introduced into a reactor, and the reactor contents are then raised to an elevated temperature to effect deposition of a catalytic surface of ruthenium black on the interior walls of the reactor. The feed stream is then maintained in the reactor for a period of time sufficient to effect at least partial oxidation of the waste materials.

  7. 15 CFR 400.31 - Manufacturing and processing activity; criteria.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Manufacturing and processing activity... ZONES BOARD Manufacturing and Processing Activity-Reviews § 400.31 Manufacturing and processing activity....” When evaluating zone and subzone manufacturing and processing activity, either as proposed in...

  8. 15 CFR 400.31 - Manufacturing and processing activity; criteria.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 2 2011-01-01 2011-01-01 false Manufacturing and processing activity... ZONES BOARD Manufacturing and Processing Activity-Reviews § 400.31 Manufacturing and processing activity....” When evaluating zone and subzone manufacturing and processing activity, either as proposed in...

  9. 15 CFR 400.31 - Manufacturing and processing activity; criteria.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 2 2012-01-01 2012-01-01 false Manufacturing and processing activity... ZONES BOARD Manufacturing and Processing Activity-Reviews § 400.31 Manufacturing and processing activity....” When evaluating zone and subzone manufacturing and processing activity, either as proposed in...

  10. Experimental investigation of surface roughness in electrical discharge turning process

    NASA Astrophysics Data System (ADS)

    Gohil, Vikas; Puri, Y. M.

    2016-10-01

    In the present study the effects of machining parameters on the average surface roughness (Ra) in electrical discharge turning (EDT) is investigated. EDT is a new machining process in which a rotary spindle is added to a conventional die-sinking EDM machine in order to produce cylindrical components. In this method a new process parameter (spindle rotation) along with pulse on time and current is introduced to study its effect on Ra. This has been done by means of full factorial design (21 × 32) of experiments. A mathematical model has been developed for Ra by regression analysis and factor effects were analyzed using analysis of variance (ANOVA). Signal-to-noise ratio analysis is used to find the optimal condition.

  11. EUV mask surface cleaning effects on lithography process performance

    SciTech Connect

    George, Simi; Baclea-an, Lorie Mae; Naulleau, Patrick; Chen, Robert J.; Liang, Ted

    2010-06-18

    The reflective, multilayer based, mask architectures for extreme ultraviolet (EUV) lithography are highly susceptible to surface oxidation and contamination. As a result, EUV masks are expected to undergo cleaning processes in order to maintain the lifetimes necessary for high volume manufacturing. For this study, the impact of repetitive cleaning of EUV masks on imaging performance was evaluated. Two, high quality industry standard, EUV masks are used for this study with one of the masks undergoing repeated cleaning and the other one kept as a reference. Lithographic performance, in terms of process window analysis and line edge roughness, was monitored after every two cleans and compared to the reference mask performance. After 8x clean, minimal degradation is observed. The cleaning cycles will be continued until significant loss imaging fidelity is found.

  12. Land use and surface process domains on alpine hillslopes

    NASA Astrophysics Data System (ADS)

    Kuhn, Nikolaus J.; Caviezel, Chatrina; Hunziker, Matthias

    2015-04-01

    Shrubs and trees are generally considered to protect hillslopes from erosion. As a consequence, shrub encroachment on mountain pastures after abandoning grazing is not considered a threat to soils. However, the abandonment of mown or grazed grasslands causes a shift in vegetation composition and thus a change in landscape ecology and geomorphology. On many alpine slopes, current changes in land use and vegetation cover are accompanied by climate change, potentially generating a new geomorphic regime. Most of the debate focuses on the effect of land abandonment on water erosion rates. Generally, an established perennial vegetation cover improves the mechanical anchoring of the soil and the regulation of the soil water budget, including runoff generation and erosion. However, changing vegetation composition affects many other above- and below-ground properties like root density, -diversity and -geometry, soil structure, pore volume and acidity. Each combination of these properties can lead to a distinct scenario of dominating surface processes, often not reflected by common erosion risk assessment procedures. The study of soil properties along a chronosequence of green alder (alnusviridis) encroachment on the Unteralptal in central Switzerland reveals that shrub encroachment changes soil and vegetation properties towards an increase of resistance to run-off related erosion processes, but a decrease of slope stability against shallow landslides. The latter are a particular threat because of the currently increasing frequency of slide-triggering high magnitude rainfalls. The potential change of process domain on alpine pastures highlights the need for a careful use of erosion models when assessing future land use and climate scenarios. In mountains, but also other intensively managed agricultural landscapes, risk assessment without the appropriate reflection on the shifting relevance of surface processes carries the risk of missing future threats to environmental

  13. Process for growing a film epitaxially upon an oxide surface and structures formed with the process

    DOEpatents

    McKee, Rodney Allen; Walker, Frederick Joseph

    1998-01-01

    A process and structure wherein a film comprised of a perovskite or a spinel is built epitaxially upon a surface, such as an alkaline earth oxide surface, involves the epitaxial build up of alternating constituent metal oxide planes of the perovskite or spinel. The first layer of metal oxide built upon the surface includes a metal element which provides a small cation in the crystalline structure of the perovskite or spinel, and the second layer of metal oxide built upon the surface includes a metal element which provides a large cation in the crystalline structure of the perovskite or spinel. The layering sequence involved in the film build up reduces problems which would otherwise result from the interfacial electrostatics at the first atomic layers, and these oxides can be stabilized as commensurate thin films at a unit cell thickness or grown with high crystal quality to thicknesses of 0.5-0.7 .mu.m for optical device applications.

  14. Process for growing a film epitaxially upon an oxide surface and structures formed with the process

    DOEpatents

    McKee, Rodney A.; Walker, Frederick J.

    1995-01-01

    A process and structure wherein a film comprised of a perovskite or a spinel is built epitaxially upon a surface, such as an alkaline earth oxide surface, involves the epitaxial build up of alternating constituent metal oxide planes of the perovskite or spinel. The first layer of metal oxide built upon the surface includes a metal element which provides a small cation in the crystalline structure of the perovskite or spinel, and the second layer of metal oxide built upon the surface includes a metal element which provides a large cation in the crystalline structure of the perovskite or spinel. The layering sequence involved in the film build up reduces problems which would otherwise result from the interfacial electrostatics at the first atomic layers, and these oxides can be stabilized as commensurate thin films at a unit cell thickness or grown with high crystal quality to thicknesses of 0.5-0.7 .mu.m for optical device applications.

  15. Innovative surface NMR signal processing to significantly improve data quality

    NASA Astrophysics Data System (ADS)

    Neyer, F. M.; Hertrich, M.; Greenhalgh, S. A.

    2010-12-01

    Surface Nuclear Magnetic Resonance (SNMR) is a relatively new geophysical technique primarily used for water detection in the shallow subsurface. Magnetic fields arising from current pulses in a surface loop antenna penetrate the subsurface and interact with the hydrogen protons of liquid water. Among the various geophysical methods, surface NMR is unique in that it is directly sensitive to water molecules. Hence it has the powerful potential to quantitatively map the water distribution with depth. The signal measurement relies on the principle of induction that creates a weak voltage in the range of nV to a few μV in the surface receiver loop. However, the record is obscured by (i) man-made, industrial, and cultural (harmonic) noise such as power-lines and railway tracks, (ii) spike events (incoherent noise), and (iii) atmospheric background noise (random). Extreme hardware requirements and the weakness of the signal cause the records to be heavily noise contaminated in general. As a consequence, efficient noise suppression techniques are required to extract the weak surface NMR signal, i.e. stacking, loop design, and digital post-processing. In this study, we present a state-of-the-art workflow for full time series NMR data processing. As a first step, random spike events are removed from all records. Reference channels are further used to create a shaping filter by which the noise component in signal record is largely reduced. In the latter stage, signal extraction is performed using digital quadrature detection with an additional phase correction. The filter design is based on a least-squares approach using different input channels. This multi-dimensional Wiener filter method allows for a multi-channel noise reduction. Today, state-of-the-art full bandwidth multi-channel recording systems offer the possibility to record four channels simultaneously. Therefore, it is possible to use up to three reference channels for noise attenuation. By analyzing the optimal

  16. Cu Nanowires with Clean Surfaces: Synthesis and Enhanced Electrocatalytic Activity.

    PubMed

    Liu, Xinmei; Sui, Yongming; Yang, Xinyi; Wei, Yingjin; Zou, Bo

    2016-10-12

    Low activity and high cost of electrocatalysts are the major challenge for the commercialization of the direct fuel cells (DFCs) and biofuel cells. In this work, we demonstrate the desirable "clean surfaces" effect of Cu nanocrystals in electrocatalysis. By a new reaction route of Cu2O nanospheres (Cu2O NSs), Cu nanowires (Cu NWs) with high purity and "clean surfaces" are first obtained under mild conditions. Benefiting from the path directing effects and abundant (100) facets, the as-prepared Cu NWs exhibit a lower overpotential to achieve the methanol electro-oxidation reaction (MOR) than that of analogous Cu nanoparticles (Cu NPs). Moreover, the "clean surfaces" provide more available active sites for the efficient transfer of electrons, enabling the Cu NWs to show their enhanced electrocatalytic activity. In the MOR, forward peak current density for the surface-cleaned Cu NWs is 2839 μA cm(-2), which is ca. 6.45-fold higher than that of the Cu NWs with residual capping molecules on their surface. The "clean surfaces" effect can also be extended to the glucose electro-oxidation reaction (GOR), and the enhancement in specific surface area activity for the Cu NWs is 11.3-fold. This work enhances the electrocatalytic performance of Cu nanocrystals without the need for additional noble metals, which opens up new avenues for utilizing non-noble metals in the DFC or biofuel cell applications.

  17. Investigation of ammonia air-surface exchange processes in a ...

    EPA Pesticide Factsheets

    Recent assessments of atmospheric deposition in North America note the increasing importance of reduced (NHx = NH3 + NH4+) forms of nitrogen (N) relative to oxidized forms. This shift in in the composition of inorganic nitrogen deposition has both ecological and policy implications. Deposition budgets developed from inferential models applied at the landscape scale, as well as regional and global chemical transport models, indicate that NH3 dry deposition contributes a significant portion of inorganic N deposition in many areas. However, the bidirectional NH3 flux algorithms employed in these models have not been extensively evaluated for North American conditions (e.g, atmospheric chemistry, meteorology, biogeochemistry). Further understanding of the processes controlling NH3 air-surface exchange in natural systems is critically needed. Based on preliminary results from the Southern Appalachian Nitrogen Deposition Study (SANDS), this presentation examines processes of NH3 air-surface exchange in a deciduous montane forest at the Coweeta Hydrologic Laboratory in western North Carolina. A combination of measurements and modeling are used to investigate net fluxes of NH3 above the forest and sources and sinks of NH3 within the canopy and forest floor. Measurements of biogeochemical NH4+ pools are used to characterize emission potential and NH3 compensation points of canopy foliage (i.e., green vegetation), leaf litter, and soil and their relation to NH3 fluxes

  18. Synchroton X-Ray Studies of Growth Processes on Surfaces

    NASA Astrophysics Data System (ADS)

    Tse, Teddy

    1995-01-01

    We present a series of studies of surface growth processes with the use of synchrotron x-ray diffraction. Submonolayer growth of Pb on Ni(001) at room temperature exhibits self -similar and exponential growth with increasing adsorbate coverage. The results indicate that site degeneracy of the surface structure is not a significant factor in limiting growth before domains come into contact. Repeating the same growth procedure at higher temperatures on Pb on Ni(001) and Pb on Cu(001) results in adsorbate aggregation at pinning sites, followed by phenomena similar to those at low temperature domain growth. Late stage monolayer growth is studied on Pb on Cu(001) in which domains of different sublattices coarsen with constant adsorbate coverage. Domains grow as annealing time to 1/2 power with self-similar diffraction lineshape, consistent with the theory for a doubly degenerate system with a nonconserved order parameter. Multilayer growth of Ag on Ag(111) shows that roughness of the growth front increases with time as a power law, as predicted by the dynamic scaling hypothesis. The value of the growth exponent is found to decrease with increasing substrate temperature. Despite the complex and distinct growth mechanisms of the above systems, the concept of scaling appears to be a powerful tool in describing the non-equilibrium processes.

  19. Surface activation-based nanobonding and interconnection at room temperature

    NASA Astrophysics Data System (ADS)

    Howlader, M. M. R.; Yamauchi, A.; Suga, T.

    2011-02-01

    Flip chip nanobonding and interconnect system (NBIS) equipment with high precision alignment has been developed based on the surface activated bonding method for high-density interconnection and MEMS packaging. The 3σ alignment accuracy in the IR transmission system was approximately ±0.2 µm. The performance of the NBIS has been preliminarily investigated through bonding between relatively rough surfaces of copper through silicon vias (Cu-TSVs) and gold-stud bumps (Au-SBs), and smooth surfaces of silicon wafers. The Cu-TSVs of 55 µm diameter and the Au-SBs of 35 µm diameter with ~6-10 nm surface roughness (RMS) were bonded at room temperature after surface activation using an argon fast atom beam (Ar-FAB) under 0.16 N per bump. Silicon wafers of 50 mm diameter with ~0.2 nm RMS surface roughness were bonded without heating after surface activation. Void-free interfaces both in Cu-TSV/Au-SB and silicon/silicon with bonding strength equivalent to bulk fracture of Au and silicon, respectively, were achieved. A few nm thick amorphous layers were observed across the silicon/silicon interface that was fabricated by the Ar-FAB. This study in the interconnection and bonding facilitates the required three-dimensional integration on the same surface for high-density electronic and biomedical systems.

  20. Activities affecting surface water resources: A general overview

    SciTech Connect

    Not Available

    1990-01-01

    In November 1987, P.E.I. signed a federal/provincial work-sharing arrangement on water resource management focusing on groundwater pollution, surface water degradation and estuarine eutrophication. The surface water program was designed to identify current surface water uses and users within 12 major watersheds across the Island containing 26 individual rivers, as well as problems arising due to practices that degrade the quality of surface water and restricts its value to other user groups. This report presents a general overview of the program, covering the general characteristics of the Island; operations in agriculture, fish and wildlife, forestry, recreation, fisheries, and industry; alterations of natural features of waterways; wetlands; additional watershed activities such as hydrometric stations and subdivision development; and activities affecting surface water resources such as sedimentation sources, pollution point sources and instream obstructions.

  1. Process-based upscaling of surface-atmosphere exchange

    NASA Astrophysics Data System (ADS)

    Keenan, T. F.; Prentice, I. C.; Canadell, J.; Williams, C. A.; Wang, H.; Raupach, M. R.; Collatz, G. J.; Davis, T.; Stocker, B.; Evans, B. J.

    2015-12-01

    Empirical upscaling techniques such as machine learning and data-mining have proven invaluable tools for the global scaling of disparate observations of surface-atmosphere exchange, but are not based on a theoretical understanding of the key processes involved. This makes spatial and temporal extrapolation outside of the training domain difficult at best. There is therefore a clear need for the incorporation of knowledge of ecosystem function, in combination with the strength of data mining. Here, we present such an approach. We describe a novel diagnostic process-based model of global photosynthesis and ecosystem respiration, which is directly informed by a variety of global datasets relevant to ecosystem state and function. We use the model framework to estimate global carbon cycling both spatially and temporally, with a specific focus on the mechanisms responsible for long-term change. Our results show the importance of incorporating process knowledge into upscaling approaches, and highlight the effect of key processes on the terrestrial carbon cycle.

  2. Surface free energy activated high-throughput cell sorting.

    PubMed

    Zhang, Xinru; Zhang, Qian; Yan, Tao; Jiang, Zeyi; Zhang, Xinxin; Zuo, Yi Y

    2014-09-16

    Cell sorting is an important screening process in microbiology, biotechnology, and clinical research. Existing methods are mainly based on single-cell analysis as in flow cytometric and microfluidic cell sorters. Here we report a label-free bulk method for sorting cells by differentiating their characteristic surface free energies (SFEs). We demonstrated the feasibility of this method by sorting model binary cell mixtures of various bacterial species, including Pseudomonas putida KT2440, Enterococcus faecalis ATCC 29212, Salmonella Typhimurium ATCC 14028, and Escherichia coli DH5α. This method can effectively separate 10(10) bacterial cells within 30 min. Individual bacterial species can be sorted with up to 96% efficiency, and the cell viability ratio can be as high as 99%. In addition to its capacity of sorting evenly mixed bacterial cells, we demonstrated the feasibility of this method in selecting and enriching cells of minor populations in the mixture (presenting at only 1% in quantity) to a purity as high as 99%. This SFE-activated method may be used as a stand-alone method for quickly sorting a large quantity of bacterial cells or as a prescreening tool for microbial discrimination. Given its advantages of label-free, high-throughput, low cost, and simplicity, this SFE-activated cell sorting method has potential in various applications of sorting cells and abiotic particles.

  3. Occurrence of Surface Active Agents in the Environment

    PubMed Central

    Olkowska, Ewa; Ruman, Marek; Polkowska, Żaneta

    2014-01-01

    Due to the specific structure of surfactants molecules they are applied in different areas of human activity (industry, household). After using and discharging from wastewater treatment plants as effluent stream, surface active agents (SAAs) are emitted to various elements of the environment (atmosphere, waters, and solid phases), where they can undergo numerous physic-chemical processes (e.g., sorption, degradation) and freely migrate. Additionally, SAAs present in the environment can be accumulated in living organisms (bioaccumulation), what can have a negative effect on biotic elements of ecosystems (e.g., toxicity, disturbance of endocrine equilibrium). They also cause increaseing solubility of organic pollutants in aqueous phase, their migration, and accumulation in different environmental compartments. Moreover, surfactants found in aerosols can affect formation and development of clouds, which is associated with cooling effect in the atmosphere and climate changes. The environmental fate of SAAs is still unknown and recognition of this problem will contribute to protection of living organisms as well as preservation of quality and balance of various ecosystems. This work contains basic information about surfactants and overview of pollution of different ecosystems caused by them (their classification and properties, areas of use, their presence, and behavior in the environment). PMID:24527257

  4. Comparison of deposited surface area of airborne ultrafine particles generated from two welding processes.

    PubMed

    Gomes, J F; Albuquerque, P C; Miranda, Rosa M; Santos, Telmo G; Vieira, M T

    2012-09-01

    This article describes work performed on the assessment of the levels of airborne ultrafine particles emitted in two welding processes metal-active gas (MAG) of carbon steel and friction-stir welding (FSW) of aluminium in terms of deposited area in alveolar tract of the lung using a nanoparticle surface area monitor analyser. The obtained results showed the dependence from process parameters on emitted ultrafine particles and clearly demonstrated the presence of ultrafine particles, when compared with background levels. The obtained results showed that the process that results on the lower levels of alveolar-deposited surface area is FSW, unlike MAG. Nevertheless, all the tested processes resulted in important doses of ultrafine particles that are to be deposited in the human lung of exposed workers.

  5. Correlated activity supports efficient cortical processing

    PubMed Central

    Hung, Chou P.; Cui, Ding; Chen, Yueh-peng; Lin, Chia-pei; Levine, Matthew R.

    2015-01-01

    Visual recognition is a computational challenge that is thought to occur via efficient coding. An important concept is sparseness, a measure of coding efficiency. The prevailing view is that sparseness supports efficiency by minimizing redundancy and correlations in spiking populations. Yet, we recently reported that “choristers”, neurons that behave more similarly (have correlated stimulus preferences and spontaneous coincident spiking), carry more generalizable object information than uncorrelated neurons (“soloists”) in macaque inferior temporal (IT) cortex. The rarity of choristers (as low as 6% of IT neurons) indicates that they were likely missed in previous studies. Here, we report that correlation strength is distinct from sparseness (choristers are not simply broadly tuned neurons), that choristers are located in non-granular output layers, and that correlated activity predicts human visual search efficiency. These counterintuitive results suggest that a redundant correlational structure supports efficient processing and behavior. PMID:25610392

  6. The Activity of Antimicrobial Surfaces Varies by Testing Protocol Utilized

    PubMed Central

    Campos, Matias D.; Zucchi, Paola C.; Phung, Ann; Leonard, Steven N.; Hirsch, Elizabeth B.

    2016-01-01

    Background Contaminated hospital surfaces are an important source of nosocomial infections. A major obstacle in marketing antimicrobial surfaces is a lack of efficacy data based on standardized testing protocols. Aim We compared the efficacy of multiple testing protocols against several “antimicrobial” film surfaces. Methods Four clinical isolates were used: one Escherichia coli, one Klebsiella pneumoniae, and two Staphylococcus aureus strains. Two industry methods (modified ISO 22196 and ASTM E2149), a “dried droplet”, and a “transfer” method were tested against two commercially available antimicrobial films, one film in development, an untreated control, and a positive (silver) control film. At 2 (only ISO) and 24 hours following inoculation, bacteria were collected from film surfaces and enumerated. Results Compared to untreated films in all protocols, there were no significant differences in recovery on either commercial brand at 2 or 24 hours after inoculation. The silver surface demonstrated significant microbicidal activity (mean loss 4.9 Log10 CFU/ml) in all methods and time points with the exception of 2 hours in the ISO protocol and the transfer method. Using our novel droplet method, no differences between placebo and active surfaces were detected. The surface in development demonstrated variable activity depending on method, organism, and time point. The ISO demonstrated minimal activity at 2 hours but significant activity at 24 hours (mean 4.5 Log10 CFU/ml difference versus placebo). The ASTEM protocol exhibited significant differences in recovery of staphylococci (mean 5 Log10 CFU/ml) but not Gram-negative isolates (10 fold decrease). Minimal activity was observed with this film in the transfer method. Conclusions Varying results between protocols suggested that efficacy of antimicrobial surfaces cannot be easily and reproducibly compared. Clinical use should be considered and further development of representative methods is needed. PMID

  7. Surface modification of food contact materials for processing and packaging applications

    NASA Astrophysics Data System (ADS)

    Barish, Jeffrey A.

    This body of work investigates various techniques for the surface modification of food contact materials for use in food packaging and processing applications. Nanoscale changes to the surface of polymeric food packaging materials enables changes in adhesion, wettability, printability, chemical functionality, and bioactivity, while maintaining desirable bulk properties. Polymer surface modification is used in applications such as antimicrobial or non-fouling materials, biosensors, and active packaging. Non-migratory active packagings, in which bioactive components are tethered to the package, offer the potential to reduce the need for additives in food products while maintaining safety and quality. A challenge in developing non-migratory active packaging materials is the loss of biomolecular activity that can occur when biomolecules are immobilized. Polyethylene glycol (PEG), a biocompatible polymer, is grafted from the surface of ozone treated low-density polyethylene (LDPE) resulting in a surface functionalized polyethylene to which a range of amine-terminated bioactive molecules can be immobilized. The grafting of PEG onto the surface of polymer packaging films is accomplished by free radical graft polymerization, and to covalently link an amine-terminated molecule to the PEG tether, demonstrating that amine-terminated bioactive compounds (such as peptides, enzymes, and some antimicrobials) can be immobilized onto PEG-grafted LDPE in the development of non-migratory active packaging. Fouling on food contact surfaces during food processing has a significant impact on operating efficiency and can promote biofilm development. Processing raw milk on plate heat exchangers results in significant fouling of proteins as well as minerals, and is exacerbated by the wall heating effect. An electroless nickel coating is co-deposited with polytetrafluoroethylene onto stainless steel to test its ability to resist fouling on a pilot plant scale plate heat exchanger. Further

  8. Morphological stability of the atomically clean surface of silicon (100) crystals after microwave plasma-chemical processing

    SciTech Connect

    Yafarov, R. K. Shanygin, V. Ya.

    2016-01-15

    The morphological stability of atomically clean silicon (100) surface after low-energy microwave plasma-chemical etching in various plasma-forming media is studied. It is found that relaxation changes in the surface density and atomic bump heights after plasma processing in inert and chemically active media are multidirectional in character. After processing in a freon-14 medium, the free energy is minimized due to a decrease in the surface density of microbumps and an increase in their height. After argon-plasma processing, an insignificant increase in the bump density with a simultaneous decrease in bump heights is observed. The physicochemical processes causing these changes are considered.

  9. Enhanced cell colonization of collagen scaffold by ultraviolet/ozone surface processing.

    PubMed

    Liu, Chaozong; McKenna, Fiona-Mairead; Liang, He; Johnstone, Alan; Abel, Eric W

    2010-12-01

    Both physical and chemical crosslinking methods have been shown to be effective in improving the biological stability and mechanical properties of porous collagen scaffolds. However, the wetting of the collagen fibril surface by a culture medium is reduced and it is difficult for the medium to diffuse into the 3D structure of a porous collagen scaffold. This article reports a strategy for the surface processing of crosslinked collagen scaffolds by an integrated ultraviolet/ozone perfuse processing technique. Ultraviolet/ozone perfuse processing improved surface wettability for both the exterior and interior surfaces of the porous 3D collagen scaffold. This leads to a significant improvement in the scaffolds ability to take up water without compromising the bulk biological stability and mechanical properties. In vitro evaluation using mesenchymal stem cell demonstrated that surface processing enhanced cell colonization of the scaffolds, cells could migrate deep into the structure of the scaffolds, and significantly higher levels of cell proliferation were achieved. In contrast, the cells were unable to migrate deep into the scaffolds, and most of the cells that survived were observed only in the top seeding layer resulting in a low level of cell activity in the unprocessed scaffolds.

  10. Research of surface activating influence on formation of adhesion between gas-thermal coating and steel substrate

    NASA Astrophysics Data System (ADS)

    Kovalevskaya, Z.; Klimenov, V.; Zaitsev, K.

    2015-09-01

    Estimation of influence of physical and thermal activating on adhesion between steel substrates and thermal coatings has been performed. The substrates with surfaces obtained by and ultrasonic surface plastic deformation were used. To evaluate physical activating, preheating of the substrates to 600°C was performed. To evaluate the effect of thermal activating, the substrate surfaces after interfacial detachment were examined. Bonded areas on the substrate surfaces were measured by means of optical profilometry. The experiments have shown that surface physical activating is the main factor in formation of the adhesive bond between the coating and the substrate processed with the proposed methods.

  11. Using Surface Curvature to Control the Dimerization of a Surface-Active Protein

    NASA Astrophysics Data System (ADS)

    Kurylowicz, Martin; Giuliani, Maximiliano; Dutcher, John

    2012-02-01

    Understanding the influence of surface geometry on adsorbed proteins promises new possibilities in biophysics, such as topographical catalysis, molecular recognition of geometric cues, and modulations of oligomerization or ligand binding. We have created nano-textured hydrophobic surfaces that are stable in buffer by spin coating polystyrene (PS) nanoparticles (NPs) to form patchy NP monolayers on a PS substrate, yielding flat and highly curved areas on the same sample. Moreover, we have separated surface chemistry from texture by floating a 10 nm thick film of monodisperse PS onto the NP-functionalized surface. Using Single Molecule Force Spectroscopy we have compared in situ the distribution of detachment lengths for proteins on curved surfaces to that measured on flat surfaces. We have shown that β-Lactoglobulin (β-LG), a surface-active protein which helps to stabilize oil droplets in milk, forms dimers on both flat PS surfaces and surfaces with a radius of curvature of 100 nm, whereas β-LG monomers exist for more highly curved surfaces with radii of curvature of 25 and 40 nm. It is surprising that rather large radii of curvature have such a strong influence on proteins whose radius is only ˜2 nm. Furthermore, the transition from dimer to monomer with changes in surface curvature offers promising applications for proteins whose function can be modified by their oligomerization state.

  12. Investigation of the effect of contaminations and cleaning processes on the surface properties of brazing surfaces

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Öte, M.; Wiesner, S.

    2017-03-01

    The quality of brazed joints is determined by different factors such as the atmosphere and the parameters during brazing as well as the condition of the brazing surfaces. Residues of lubricants used during machining of the components and the subsequent cleaning processes can contaminate the faying surfaces and can hence influence the flow ability of the molten filler metals. Besides their influence on the filler metal flow, the residues can result in the formation of carbonic phases in the joint leading to a possible reduction of the corrosion resistance and the mechanical properties. The first step of the current study with the aim of avoiding these defects is to identify the influence of critical contaminations and cleaning methods on the quality of the brazed joints. In a first step, contaminations on AISI304 and Inconel alloy 625 due to different cooling lubricants and the effect of several cleaning methods, in particular plasma cleaning, have been investigated. Information about the surface energy of contaminated and cleaned surfaces was gained by measuring contact angle of testing fluids. Additionally, the lubricants and the resulting contamination products have been analyzed considering the influence of a heat treatment.

  13. Image processing of metal surface with structured light

    NASA Astrophysics Data System (ADS)

    Luo, Cong; Feng, Chang; Wang, Congzheng

    2014-09-01

    In structured light vision measurement system, the ideal image of structured light strip, in addition to black background , contains only the gray information of the position of the stripe. However, the actual image contains image noise, complex background and so on, which does not belong to the stripe, and it will cause interference to useful information. To extract the stripe center of mental surface accurately, a new processing method was presented. Through adaptive median filtering, the noise can be preliminary removed, and the noise which introduced by CCD camera and measured environment can be further removed with difference image method. To highlight fine details and enhance the blurred regions between the stripe and noise, the sharping algorithm is used which combine the best features of Laplacian operator and Sobel operator. Morphological opening operation and closing operation are used to compensate the loss of information.Experimental results show that this method is effective in the image processing, not only to restrain the information but also heighten contrast. It is beneficial for the following processing.

  14. [Thermodynamics process of laser drilling on copper surface].

    PubMed

    Li, Shi-Wen; Zhang, Qiu-Hui; Niu, Rui-Hua

    2013-04-01

    The laser drilling experiment was carried out on the copper surface by ns laser pulse, then the micro-morphology of the micro-hole was observed and the thermodynamic process was analyzed accordingly. The research results show that micro-hole is made of the pit in the center and surrounding uplift. The pit becomes deeper with the incident laser pulse energy. The thermodynamic analysis indicates that laser drilling on the metal requires two basic conditions: the first is the deposition of laser pulse energy, which makes the occurrence of melting, vaporization and ionization. Such phase transition can make the materials easy to remove and the laser plasma can accelerate the laser pulse energy deposition as the secondary heat source. The second condition is the production of the laser plasma shock wave, it can eject the materials of phase transition effectively and timely, thus the micro hole can be formed.

  15. Applications of Time-Reversal Processing for Planetary Surface Communications

    NASA Technical Reports Server (NTRS)

    Barton, Richard J.

    2007-01-01

    Due to the power constraints imposed on wireless sensor and communication networks deployed on a planetary surface during exploration, energy efficient transfer of data becomes a critical issue. In situations where groups of nodes within a network are located in relatively close proximity, cooperative communication techniques can be utilized to improve the range, data rate, power efficiency, and lifetime of the network. In particular, if the point-to-point communication channels on the network are well modeled as frequency non-selective, distributed or cooperative beamforming can employed. For frequency-selective channels, beamforming itself is not generally appropriate, but a natural generalization of it, time-reversal communication (TRC), can still be effective. Time-reversal processing has been proposed and studied previously for other applications, including acoustical imaging, electromagnetic imaging, underwater acoustic communication, and wireless communication channels. In this paper, we study both the theoretical advantages and the experimental performance of cooperative TRC for wireless communication on planetary surfaces. We give a brief introduction to TRC and present several scenarios where TRC could be profitably employed during planetary exploration. We also present simulation results illustrating the performance of cooperative TRC employed in a complex multipath environment and discuss the optimality of cooperative TRC for data aggregation in wireless sensor networks

  16. Active surface model improvement by energy function optimization for 3D segmentation.

    PubMed

    Azimifar, Zohreh; Mohaddesi, Mahsa

    2015-04-01

    This paper proposes an optimized and efficient active surface model by improving the energy functions, searching method, neighborhood definition and resampling criterion. Extracting an accurate surface of the desired object from a number of 3D images using active surface and deformable models plays an important role in computer vision especially medical image processing. Different powerful segmentation algorithms have been suggested to address the limitations associated with the model initialization, poor convergence to surface concavities and slow convergence rate. This paper proposes a method to improve one of the strongest and recent segmentation algorithms, namely the Decoupled Active Surface (DAS) method. We consider a gradient of wavelet edge extracted image and local phase coherence as external energy to extract more information from images and we use curvature integral as internal energy to focus on high curvature region extraction. Similarly, we use resampling of points and a line search for point selection to improve the accuracy of the algorithm. We further employ an estimation of the desired object as an initialization for the active surface model. A number of tests and experiments have been done and the results show the improvements with regards to the extracted surface accuracy and computational time of the presented algorithm compared with the best and recent active surface models.

  17. Exchange processes from the deep interior to the surface of icy moons

    NASA Astrophysics Data System (ADS)

    Grasset, O.

    Space exploration provides outstanding images of planetary surfaces. Galileo space- craft around Jupiter, and now Cassini in the saturnian system have revealed to us the variety of icy surfaces in the solar system. While Europa, Enceladus, and maybe Titan present past or even active tectonic and volcanic activities, many other moons have been dead worlds for more than 3 billions years. Composition of ices is also complex and it is now commonly admitted that icy surfaces are never composed of pure ices. Water ice can be mixed with salts (Europa?), with hydrocarbons (Titan?) or with silicates (Callisto). The present surfaces of icy moons are the results of both internal (tectonic; volcanism; mantle composition; magnetic field; . . . ) and external processes (radiations, atmospheres, impacts, . . . ). Internal activity (past or present) is almost unknown. While the surfaces indicate clearly that an important activity existed (Ganymede, Europa, Titan, . . . ) or still exists (Enceladus, Titan?, . . . ), volcanic and tectonic processes within icy mantles are still very poorly understood. This project proposes some key studies for improving our knowledge of exchange processes within icy moons, which are: 1) Surface compositions: Interpretation of mapping spectrometer data. It addresses the interpretation of remote sensing data. These data are difficult to understand and a debate between people involved in Galileo and those who are now trying to interpret Cassini data might be fruitful. As an example, interpretation of Galileo data on Europa are still controversial. It is impossible to affirm that the "non-icy" material which does not present the classic infrared signature of pure ice is due to the presence of magnesium hydrates, sodium hydrates, magnesium sulfurs, "clays", or even altered water ice. Discussion on the subject are still needed. On Titan, the presence of the atmosphere impedes to link IR data from Cassini to the composition of the surface. 2) Past and

  18. The Amazon River reversal explained by tectonic and surface processes

    NASA Astrophysics Data System (ADS)

    Sacek, V.

    2014-12-01

    The drainage pattern in Amazonia was expressively modified during the mountain building of central and northern Andes. In Early Miocene, the fluvial systems in western Amazonia flowed to the foreland basins and northward to the Caribbean. By Late Miocene the drainage reversal occurred and formed the transcontinental Amazon River, connecting the Andes and the equatorial Atlantic margin. This event is recorded in the stratigraphic evolution of the Foz do Amazonas Basin by the onset of Andean-derived sedimentation. Additionally, an abrupt increase in sedimentation rate after the reversal occurred in the Foz do Amazonas Basin. Based on three-dimensional numerical models that couple surface processes, flexural isostasy and crustal thickening due to orogeny, I concluded that the Miocene drainage reversal can be explained by the flexural and surface processes response to the Andes formation with no need to invoke dynamic topography induced by mantle convection, as previously proposed. I observed that the instant of drainage reversal is directly linked to the rate of crustal thickening in the orogeny, the rate of erosion and, mainly, the efficiency of sediment transport. Moreover, the numerical experiments were able to predict the increase in sedimentation rate in the Amazon fan after the drainage reversal of the Amazon River as observed in the Late Miocene-Pliocene sedimentary record. However, the present numerical model fails to fully reproduce the evolution of the Pebas system, a megawetland in western Amazonia that preceded the drainage reversal. Therefore, further investigation is necessary to evaluate the mechanisms that generated and sustained the Pebas system.

  19. Air plasma processing of poly(methyl methacrylate) micro-beads: Surface characterisations

    NASA Astrophysics Data System (ADS)

    Liu, Chaozong; Cui, Nai-Yi; Osbeck, Susan; Liang, He

    2012-10-01

    This paper reports the surface processing of poly(methyl methacrylate) (PMMA) micro-beads by using a rotary air plasma reactor, and its effects on surface properties. The surface properties, including surface wettability, surface chemistry and textures of the PMMA beads, were characterised. It was observed that the air plasma processing can improve the surface wettability of the PMMA microbeads significantly. A 15 min plasma processing can reduce the surface water contact angle of PMMA beads to about 50° from its original value of 80.3°. This was accompanied by about 8% increase in surface oxygen concentration as confirmed by XPS analysis. The optical profilometry examination revealed the air plasma processing resulted in a rougher surface that has a “delicate” surface texture. It is concluded that the surface chemistry and texture, induced by air plasma processing, co-contributed to the surface wettability improvement of PMMA micro-beads.

  20. Hierarchically nanoporous ceria nanoparticles with a high-surface area: synthesis, characterization, and their catalytic activity.

    PubMed

    Ge, Jiechao; Zhong, Liangshu; Zhuo, Linhai; Tang, Bo; Song, Weiguo

    2011-01-01

    A redox route based on ethylene glycol mediated process was developed to synthesize hierarchically nanoporpous ceria nanoparticles (ceria HNPNPs). The synthesized ceria HNPNPs are composed of building blocks fabricated with cubic ceria nanocrystals of several nanometers in diameter. Scanning electron microscopy was performed to investigate the evolution process of ceria precursor, and a two-step growth process was suggested for the morphology evolution. The synthesized ceria HNPNPs exhibit high surface area, which lead to high catalytic activity for CO oxidation.

  1. Surface Activation of Faceted Photocatalyst: When Metal Cocatalyst Determines the Nature of the Facets.

    PubMed

    Wang, Bin; Liu, Maochang; Zhou, Zhaohui; Guo, Liejin

    2015-11-01

    Pt nanoparticles with tunable size are prepared on the entire surface of facet-engineered Cu2WS4 decahedral photocatalyst via a kinetic-controlled chemical reduction process. The {101} facets of the photocatalyst which featured photo-oxidation, are successfully activated for photoreduction by Pt. The resulting photocatalyst shows an activity nine times higher compared to that of the only {001}-facets activated catalyst obtained by a conventional in situ photodeposition route.

  2. Regulation of tissue factor coagulant activity on cell surfaces

    PubMed Central

    RAO, L.V.M.; PENDURTHI, U.R.

    2012-01-01

    Summary Tissue factor (TF) is a transmembrane glycoprotein and an essential component of factor VIIa-TF enzymatic complex that triggers activation of the coagulation cascade. Formation of TF-FVIIa complexes on cell surfaces not only trigger the coagulation cascade but also transduce cell signaling via activation of protease-activated receptors. Tissue factor is expressed constitutively on cell surfaces of a variety of extravascular cell types, including fibroblasts and pericytes in and surrounding blood vessel walls and epithelial cells but generally absent on cells that come in contact with blood directly. However, TF expression could be induced in some blood cells, such as monocytes and endothelial cells, following an injury or pathological stimuli. Tissue factor is essential for hemostasis, but aberrant expression of TF leads to thrombosis. Therefore, a proper regulation of TF activity is critical for the maintenance of hemostatic balance and health in general. TF-FVIIa coagulant activity at the cell surface is influenced not only by TF protein expression levels but also independently by a variety of mechanisms, including alterations in membrane phospholipid composition and cholesterol content, thiol-dependent modifications of TF allosteric disulfide bond, and other post-translational modifications of TF. In this article, we critically review key literature on mechanisms by which TF coagulant activity is regulated at the cell surface in the absence of changes in TF protein levels with specific emphasis on recently published data and provide the authors’ perspective on the subject. PMID:23006890

  3. Multi-surface topography targeted plateau honing for the processing of cylinder liner surfaces of automotive engines

    NASA Astrophysics Data System (ADS)

    Lawrence, K. Deepak; Ramamoorthy, B.

    2016-03-01

    Cylinder bores of automotive engines are 'engineered' surfaces that are processed using multi-stage honing process to generate multiple layers of micro geometry for meeting the different functional requirements of the piston assembly system. The final processed surfaces should comply with several surface topographic specifications that are relevant for the good tribological performance of the engine. Selection of the process parameters in three stages of honing to obtain multiple surface topographic characteristics simultaneously within the specification tolerance is an important module of the process planning and is often posed as a challenging task for the process engineers. This paper presents a strategy by combining the robust process design and gray-relational analysis to evolve the operating levels of honing process parameters in rough, finish and plateau honing stages targeting to meet multiple surface topographic specifications on the final running surface of the cylinder bores. Honing experiments were conducted in three stages namely rough, finish and plateau honing on cast iron cylinder liners by varying four honing process parameters such as rotational speed, oscillatory speed, pressure and honing time. Abbott-Firestone curve based functional parameters (Rk, Rpk, Rvk, Mr1 and Mr2) coupled with mean roughness depth (Rz, DIN/ISO) and honing angle were measured and identified as the surface quality performance targets to be achieved. The experimental results have shown that the proposed approach is effective to generate cylinder liner surface that would simultaneously meet the explicit surface topographic specifications currently practiced by the industry.

  4. Rapid rotation and mixing in active OB stars - Physical processes

    NASA Astrophysics Data System (ADS)

    Zahn, Jean-Paul

    2011-07-01

    In the standard description of stellar interiors, O and B stars possess a thoroughly mixed convective core surrounded by a stable radiative envelope in which no mixing occurs. But as is well known, this model disagrees strongly with the spectroscopic diagnostic of these stars, which reveals the presence at their surface of chemical elements that have been synthesized in the core. Hence the radiation zone must be the seat of some mild mixing mechanisms. The most likely to operate there are linked with the rotation: these are the shear instabilites triggered by the differential rotation, and the meridional circulation caused by the changes in the rotation profile accompanying the non-homologous evolution of the star. In addition to these hydrodynamical processes, magnetic stresses may play an important role in active stars, which host a magnetic field. These physical processes will be critically examined, together with some others that have been suggested.

  5. Surface ion trap structures with excellent optical access for quantum information processing

    NASA Astrophysics Data System (ADS)

    Maunz, P.; Blain, M.; Benito, F.; Chou, C.; Clark, C.; Descour, M.; Ellis, R.; Haltli, R.; Heller, E.; Kemme, S.; Sterk, J.; Tabakov, B.; Tigges, C.; Stick, D.

    2013-05-01

    Microfabricated surface electrode ion traps are necessary for the advancement of trapped ion quantum information processing as it offers a scalable way for realizing complex trap structures capable of storing and controlling many ions. The most promising way of performing two-qubit quantum gates in a chain of trapped ions is to focus laser beams on individual ions of the chain to drive gates. However, in surface ion traps the close proximity of the ions to the surface and the size of the chips usually cannot accommodate the tightly focused laser beams necessary to address individual ions parallel to the chip surface. Here we present a surface electrode ion trap monolithically fabricated in standard silicon technology that implements a linear quadrupole trap on a bowtie shaped chip with a narrow section that is only 1.2 mm wide. Laser beams parallel to the surface can be focused down to a waist of 4 μm with enough separation from the trap chip to prevent light scattering. The trap structure incorporates two Y-junctions for reordering ions and is optimized for quantum information processing. This work was supported by the Intelligence Advanced Research Projects Activity (IARPA). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  6. Antibotulinal activity of process cheese ingredients.

    PubMed

    Glass, Kathleen A; Johnson, Eric A

    2004-08-01

    Ingredients used in the manufacture of reduced-fat process cheese products were screened for their ability to inhibit growth of Clostridium botulinum serotypes A and B in media. Reinforced clostridial medium (RCM) supplemented with 0, 0.5, 1, 2, 3, 5, or 10% (wt/vol) of various ingredients, including a carbohydrate-based fat replacer, an enzyme-modified cheese (EMC) derived from a Blue cheese, sweet whey, modified whey protein, or whey protein concentrate, did not inhibit botulinal growth and toxin production when stored at 30 degrees C for 1 week. In contrast, RCM supplemented with 10% soy-based flavor enhancer, 10% Parmesan EMC, or 5 or 10% Cheddar EMC inhibited botulinal toxin production in media for at least 6 weeks of storage at 30 degrees C. Subsequent trials revealed that the antibotulinal effect varied significantly among 13 lots of EMC and that the antimicrobial effect was not correlated with the pH or water activity of the EMC.

  7. Process for leveling film surfaces and products thereof

    DOEpatents

    Birkmire, R.W.; McCandless, B.E.

    1990-03-20

    Semiconductor films and photovoltaic devices prepared therefrom are provided wherein the semiconductor films have a specular surface with a texture less than about 0.25 micron greater than the average planar film surface and wherein the semiconductor films are surface modified by exposing the surface to an aqueous solution of bromine containing an acid or salt and continuing such exposure for a time sufficient to etch the surface. 8 figs.

  8. Process for levelling film surfaces and products thereof

    DOEpatents

    Birkmire, Robert W.; McCandless, Brian E.

    1990-03-20

    Semiconductor films and photovoltaic devices prepared therefrom are provided wherein the semiconductor films have a specular surface with a texture less than about 0.25 micron greater than the average planar film surface and wherein the semiconductor films are surface modified by exposing the surface to an aqueous solution of bromine containing an acid or salt and continuing such exposure for a time sufficient to etch the surface.

  9. Control surface spanwise placement in active flutter suppression systems

    NASA Technical Reports Server (NTRS)

    Nissim, E.; Burken, John J.

    1988-01-01

    A method is developed that determines the placement of an active control surface for maximum effectiveness in suppressing flutter. No specific control law is required by this method which is based on the aerodynamic energy concept. It is argued that the spanwise placement of the active controls should coincide with the locations where maximum energy per unit span is fed into the system. The method enables one to determine the distribution, over the different surfaces of the aircraft, of the energy input into the system as a result of the unstable fluttering mode. The method is illustrated using three numerical examples.

  10. A simplified process design for P450 driven hydroxylation based on surface displayed enzymes.

    PubMed

    Ströhle, Frank W; Kranen, Eva; Schrader, Jens; Maas, Ruth; Holtmann, Dirk

    2016-06-01

    New production routes for fine and bulk chemicals are important to establish further sustainable processes in industry. Besides the identification of new biocatalysts and new production routes the optimization of existing processes in regard to an improved utilization of the catalysts are needed. In this paper we describe the successful expression of P450BM3 on the surface of E. coli cells with the Autodisplay system. The successful hydroxylation of palmitic acid by using surface-displayed P450BM3 was shown. Besides optimization of surface protein expression, several cofactor regeneration systems were compared and evaluated. Afterwards, the development of a suitable process for the biocatalytic hydroxylation of fatty acids based on the re-use of the catalysts after a simple centrifugation was investigated. It was shown that the catalyst can be used for several times without any loss in activity. By using surface-displayed P450s in combination with an enzymatic cofactor regeneration system a total turnover number of up to 54,700 could be reached, to the knowledge of the authors the highest value reported for a P450 monooxygenase to date. Further optimizations of the described reaction system can have an enormous impact on the process design for more sustainable bioprocesses. Biotechnol. Bioeng. 2016;113: 1225-1233. © 2015 Wiley Periodicals, Inc.

  11. Cross comparisons of land surface process descriptions in land surface models using multiple sources of data

    NASA Astrophysics Data System (ADS)

    Park, Gi Hyeon

    2006-12-01

    Land surface-atmospheric interactions influence climate and weather varying spatial scales from local to mesoscale, and even to global. This dissertation deals with several topics: (1) evaluation of various sources of incoming solar radiations, (2) evaluation of land surface process descriptions in the land surface models in both basin-scale and point scale offline model simulations, and (3) inverse estimation of radiation components using net radiation and other meteorological variables. Incoming solar radiations from various sources were evaluated. This study identified the two sources of errors in the North American Data Assimilation system (NLDAS) solar radiation: One is related to bias inherited from the ETA Data Assimilation System (EDAS) during 2001 and 2003, and the other is software error at NESDIS operational system during 2002. Land surface processes are treated quite differently in the land surface models used in this study. Over the state of Oklahoma, Common Land Model 2.1 (CLM2.1) estimates more evaporation but less transpiration than the Variable Infiltration Capacity (VIC3L) model. This is due to the difference in the runoff algorithm, which results in more infiltration down to the soil layer and then providing more available water to plant roots in VIC3L. CLM2.1 overestimates ground heat flux in Point scale simulation. CoLM, which employs two stream radiative transfer scheme, shows better agreements to adjusted ground observations (using Bowen-ration closure method) in offline simulations than CLM2.1. CoLM, in addition, shows various model behaviors depending on vegetation cover types. Inverse radiation estimation methods were developed and evaluated at four AmeriFlux sites. Analysis of observed radiations showed a triangle shape relationship among net radiation, net solar radiation and cloud factor (defined in this study). Clear-sky downward longwave radiation is needed to be calibrated for each site. SCE-UA method was used to calibrate an

  12. High surface area microporous activated carbons prepared from Fox nut (Euryale ferox) shell by zinc chloride activation

    NASA Astrophysics Data System (ADS)

    Kumar, Arvind; Mohan Jena, Hara

    2015-11-01

    High surface area microporous activated carbon has been prepared from Fox nutshell (Euryale ferox) by chemical activation with ZnCl2 as an activator. The process has been conducted at different impregnation (ZnCl2/Fox nutshell) ratios (1-2.5) and carbonization temperatures (500-700 °C). The thermal decomposition behavior of Fox nutshell and impregnated Fox nutshell has been carried out by thermogravimetric analysis. The pore properties including the BET surface area, micropore surface area, micropore volume, and pore size distribution of the activated carbons have been determined by nitrogen adsorption-desorption isotherms at -196 °C using the BET, t-plot method, DR, and BJH methods. The BET surface area, the microporous surface area, total pore volume, and micropore volume have been obtained as 2869 m2/g, 2124 m2/g, 1.96 cm3/g, and 1.68 cm3/g, respectively, and the microporosity percentage of the prepared activated carbon is 85.71%. The prepared activated carbons have been also characterized with instrumental methods such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM).

  13. Degassing Processes at Persistently Active Explosive Volcanoes

    NASA Astrophysics Data System (ADS)

    Smekens, Jean-Francois

    Among volcanic gases, sulfur dioxide (SO2) is by far the most commonly measured. More than a monitoring proxy for volcanic degassing, SO 2 has the potential to alter climate patterns. Persistently active explosive volcanoes are characterized by short explosive bursts, which often occur at periodic intervals numerous times per day, spanning years to decades. SO 2 emissions at those volcanoes are poorly constrained, in large part because the current satellite monitoring techniques are unable to detect or quantify plumes of low concentration in the troposphere. Eruption plumes also often show high concentrations of ash and/or aerosols, which further inhibit the detection methods. In this work I focus on quantifying volcanic gas emissions at persistently active explosive volcanoes and their variations over short timescales (minutes to hours), in order to document their contribution to natural SO2 flux as well as investigate the physical processes that control their behavior. In order to make these measurements, I first develop and assemble a UV ground-based instrument, and validate it against an independently measured source of SO2 at a coal-burning power plant in Arizona. I establish a measurement protocol and demonstrate that the instrument measures SO 2 fluxes with < 20 % error. Using the same protocol, I establish a record of the degassing patterns at Semeru volcano (Indonesia), a volcano that has been producing cycles of repeated explosions with periods of minutes to hours for the past several decades. Semeru produces an average of 21-71 tons of SO2 per day, amounting to a yearly output of 8-26 Mt. Using the Semeru data, along with a 1-D transient numerical model of magma ascent, I test the validity of a model in which a viscous plug at the top of the conduit produces cycles of eruption and gas release. I find that it can be a valid hypothesis to explain the observed patterns of degassing at Semeru. Periodic behavior in such a system occurs for a very narrow range

  14. Photochemical Transformation Processes in Sunlit Surface Waters (Invited)

    NASA Astrophysics Data System (ADS)

    Vione, D.

    2013-12-01

    Photochemical reactions are major processes in the transformation of hardly biodegradable xenobiotics in surface waters. They are usually classified into direct photolysis and indirect or sensitised degradation. Direct photolysis requires xenobiotic compounds to absorb sunlight, and to get transformed as a consequence. Sensitised transformation involves reaction with transient species (e.g. °OH, CO3-°, 1O2 and triplet states of chromophoric dissolved organic matter, 3CDOM*), photogenerated by so-called photosensitisers (nitrate, nitrite and CDOM). CDOM is a major photosensitiser: is it on average the main source of °OH (and of CO3-° as a consequence, which is mainly produced upon oxidation by °OH of carbonate and bicarbonate) and the only important source of 1O2 and 3CDOM* [1, 2]. CDOM origin plays a key role in sensitised processes: allochthonous CDOM derived from soil runoff and rich in fulvic and humic substances is usually more photoactive than autochthonous CDOM (produced by in-water biological processes and mainly consisting of protein-like material) or of CDOM derived from atmospheric deposition. An interesting gradual evolution of CDOM origin and photochemistry can be found in mountain lakes across the treeline, which afford a gradual transition of allochthonous- autochtonous - atmopheric CDOM when passing from trees to alpine meadows to exposed rocks [3]. Another important issue is the sites of reactive species photoproduction in CDOM. While there is evidence that smaller molecular weight fractions are more photoactive, some studies have reported considerable 1O2 reactivity in CDOM hydrophobic sites and inside particles [4]. We have recently addressed the problem and found that dissolved species in standard humic acids (hydrodynamic diameter < 0.1 μm) account for the vast majority of 1O2 and triplet states photoproduction. In hydrophobic sites of particles, the formation rate of 1O2 is considerably lower than in the solution bulk [5], but the absence

  15. Land-surface processes and monsoon climate system

    NASA Astrophysics Data System (ADS)

    Xue, Yongkang; De Sales, Fernando; Lau, William; Boone, Arron; Mechoso, Carlos

    2015-04-01

    Yongkang Xue, F. De Sales, B. Lau, A. Boone, C. R. Mechoso Differential thermal heating of land and ocean and heat release into the atmosphere are important factors that determine the onset, strength, duration and spatial distribution of large-scale monsoons. A global and seasonal assessment of land surface process (LSP) effects on the monsoon system has been made based on general circulation models (GCM) coupled to different benchmark land models, which physically represent either comprehensive, or partial, or minimal LSP representations. Observed precipitation is applied as constrain and differences in simulation error are used to assess the effect of the LSP with different complexity. The AGCM results indicate that the land/atmosphere interaction has substantial impact on global water cycle, while the monsoon regions have had strongest impact at intraseasonal to decadal scales. Among monsoon regions, West Africa, South Asia, East Asia, and Amazon regions have largest impact while some monsoon regions have less impact due to strong air/sea interactions and narrow land mass there. LSP reduces the annual precipitation error by 58% over global monsoon regions, about 35% observed precipitation. The partial LSP effect (excluding soil moisture and vegetation albedo) reduces annual precipitation error over monsoon region that equals to about 13% of observed precipitation. The LSP affects the monsoon evolution through different mechanisms at different scales. It affects the surface energy balance and energy partitioning in latent and sensible heat, the atmospheric heating rate, and general circulation. The LSP effects have also been assessed in the land use land cover change experiment. Based on recently compiled global land-use data from 1948-2005, the GCM simulation results indicate the degradation in Mexico, West Africa, south and East Asia and South America produce substantial precipitation anomalies, some of which are consistent with observed regional precipitation

  16. Raman spectroscopy - in situ characterization of growth and surface processes

    NASA Astrophysics Data System (ADS)

    Perkins, James Robert

    The goal of this thesis is to expand on the usefulness of Raman spectroscopy as an in situ probe to aid in the growth and implementation of electronic, optical, and biodetection materials. We accomplish this goal by developing two diverse optical characterization projects. In the first project, an autoclave similar to those used in solvothermal growth which has been outfitted with an optical window is used to collect vibrational spectra of solvents and mineralizers commonly used in the ammonothermal growth of gallium nitride. Secondly, novel silver nanowires created by ferroelectric lithography are evaluated by surface enhanced micro-Raman spectroscopy for use as surface enhanced substrates for low detection limit or single molecule bio-detectors. Raman spectroscopy is already a widely accepted method to characterize and identify a wide variety of materials. Vibrational spectra can yield much information on the presence of chemical species as well as information regarding the phase and interactive properties. Because Raman spectroscopy is a generally non-intrusive technique it is ideal for analysis of hazardous or far-from-ambient liquids, gases, or solids. This technique is used in situ to characterize crystal growth and surface enhanced photochemistry. The phenomenon of Surface Enhanced Raman Spectroscopy (SERS) has been observed in many systems but some fundamental understanding is still lacking and the technique has been slow to transition from the laboratory to the industry. Aggregated colloids and lithographically created islands have shown the best success as reproducible substrates for SERS detection. These techniques, however, lack control over shape, size, and position of the metal nanoparticles which leave them reliant on hotspots. Because of the potential for control of the position of aggregates, ferroelectric lithographically created silver nanowires are evaluated as a potential SERS substrate using pyridine, benzoic acid, and Rhodamine 6g. Surface

  17. Effects of nitrogen plasma treatment on the surface characteristics of olive stone-based activated carbon.

    PubMed

    Soudani, Nouha; Najar-Souissi, Souad; Abderkader-Fernandez, Victor K; Ouederni, Abdelmottalab

    2017-04-01

    Nitrogen plasma treatment (NPT) of activated carbon (AC) at different conditions was carried out to introduce nitrogen-containing groups onto olive stone-activated carbon (OSAC) surfaces. Textural characteristics of raw and irradiated samples were analyzed by N2 and CO2 adsorption. Surface chemical functional groups were analyzed by X-ray photoelectron spectrometry (XPS) and Fourier Transformed Infrared spectroscopy. The results showed that after NPT, the surface textural properties of irradiated OSAC were slightly damaged, and a gradual decrease in surface area and pore volume was observed during the irradiation. XPS revealed that NPT could change the distribution of oxygen functional groups on the OSAC surface and there were more nitrogen atoms incorporated into the aromatic ring. A tentative explanation for the modification process is proposed. Phenol adsorption was enhanced from 110 mg/g for untreated AC to 635 mg/g for 30-min plasma-treated OSAC.

  18. Changes in Sea Surface Temperature and North Atlantic Hurricane Activities

    NASA Astrophysics Data System (ADS)

    Nazari, R.; Mahani, S.; Khanbilvardi, R.

    2006-05-01

    People of United States from Maine to Texas in the years 1995 to 2005 experienced the highest level of North Atlantic hurricane activity in the reliable collected data and reports in compare with the generally low activity of the previous two decays (1970 to 1994). The greater activity might be a consequence of instantaneous changes in North Atlantic Sea Surface Temperature (SST) and air temperature. This thermal energy of increased Sea Surface Temperature (warm water) is known as tropical cyclone heat potential (TCHP) partly powers a hurricane and has been called hurricane fuel. In primary steps of this research we are trying to examine the association of variation of Sea Surface Temperature (SST), Sea Surface Height (SSH) and air temperature in the past decades with changes in hurricane number, duration and intensity. Preliminary analysis demonstrated that there is correlation between global warming and the occurrence of hurricanes because of the anticipated enhancement of energy available to the storms due to higher sea surface temperatures. The goal is to characterize and specify significant factors on tropical storms to improve the capability of predicting a hurricane and its damages to human lives and the economy. This information can be used to advise strategies for warning and also minimizing the magnitude of hurricane destruction, damages, and life losses.

  19. Activating the microscale edge effect in a hierarchical surface for frosting suppression and defrosting promotion.

    PubMed

    Chen, Xuemei; Ma, Ruiyuan; Zhou, Hongbo; Zhou, Xiaofeng; Che, Lufeng; Yao, Shuhuai; Wang, Zuankai

    2013-01-01

    Despite extensive progress, current icephobic materials are limited by the breakdown of their icephobicity in the condensation frosting environment. In particular, the frost formation over the entire surface is inevitable as a result of undesired inter-droplet freezing wave propagation initiated by the sample edges. Moreover, the frost formation directly results in an increased frost adhesion, posing severe challenges for the subsequent defrosting process. Here, we report a hierarchical surface which allows for interdroplet freezing wave propagation suppression and efficient frost removal. The enhanced performances are mainly owing to the activation of the microscale edge effect in the hierarchical surface, which increases the energy barrier for ice bridging as well as engendering the liquid lubrication during the defrosting process. We believe the concept of harnessing the surface morphology to achieve superior performances in two opposite phase transition processes might shed new light on the development of novel materials for various applications.

  20. Publications of the Western Earth Surfaces Processes Team 2005

    USGS Publications Warehouse

    Powell, Charles; Stone, Paul

    2007-01-01

    Introduction The Western Earth Surface Processes Team (WESPT) of the U.S. Geological Survey (USGS) conducts geologic mapping, earth-surface process investigations, and related topical earth science studies in the western United States. This work is focused on areas where modern geologic maps and associated earth-science data are needed to address key societal and environmental issues such as ground-water quality, landslides and other potential geologic hazards, and land-use decisions. Areas of primary emphasis in 2005 included southern California, the San Francisco Bay region, the Mojave Desert, the Colorado Plateau region of northern Arizona, and the Pacific Northwest. The team has its headquarters in Menlo Park, California, and maintains smaller field offices at several other locations in the western United States. The results of research conducted by the WESPT are released to the public as a variety of databases, maps, text reports, and abstracts, both through the internal publication system of the USGS and in diverse external publications such as scientific journals and books. This report lists publications of the WESPT released in 2005 as well as additional 2002, 2003, and 2004 publications that were not included in the previous lists (USGS Open-File Reports 03-363, 2004- 1267, 2005-1362). Most of the publications listed were authored or coauthored by WESPT staff. The list also includes some publications authored by non-USGS cooperators with the WESPT, as well as some authored by USGS staff outside the WESPT in cooperation with WESPT projects. Several of the publications listed are available on the World Wide Web; for these, URL addresses are provided. Many of these web publications are USGS Open-File reports that contain large digital databases of geologic map and related information. Information on ordering USGS publications can be found on the World Wide Web at http://www.usgs.gov/pubprod/, or by calling 1-888-ASK-USGS. The U.S. Geological Survey's web

  1. Active screen plasma nitriding enhances cell attachment to polymer surfaces

    NASA Astrophysics Data System (ADS)

    Kaklamani, Georgia; Bowen, James; Mehrban, Nazia; Dong, Hanshan; Grover, Liam M.; Stamboulis, Artemis

    2013-05-01

    Active screen plasma nitriding (ASPN) is a well-established technique used for the surface modification of materials, the result of which is often a product with enhanced functional performance. Here we report the modification of the chemical and mechanical properties of ultra-high molecular weight poly(ethylene) (UHMWPE) using 80:20 (v/v) N2/H2 ASPN, followed by growth of 3T3 fibroblasts on the treated and untreated polymer surfaces. ASPN-treated UHMWPE showed extensive fibroblast attachment within 3 h of seeding, whereas fibroblasts did not successfully attach to untreated UHMWPE. Fibroblast-coated surfaces were maintained for up to 28 days, monitoring their metabolic activity and morphology throughout. The chemical properties of the ASPN-treated UHMWPE surface were studied using X-ray photoelectron spectroscopy, revealing the presence of Csbnd N, Cdbnd N, and Ctbnd N chemical bonds. The elastic modulus, surface topography, and adhesion properties of the ASPN-treated UHMWPE surface were studied over 28 days during sample storage under ambient conditions and during immersion in two commonly used cell culture media.

  2. 30 CFR 910.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... surface coal mining operations. 910.764 Section 910.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE GEORGIA § 910.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface...

  3. 30 CFR 903.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... surface coal mining operations. 903.764 Section 903.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE ARIZONA § 903.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface...

  4. 30 CFR 905.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... surface coal mining operations. 905.764 Section 905.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE CALIFORNIA § 905.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface...

  5. 30 CFR 912.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... surface coal mining operations. 912.764 Section 912.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE IDAHO § 912.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface...

  6. Surface passivation process of compound semiconductor material using UV photosulfidation

    DOEpatents

    Ashby, Carol I. H.

    1995-01-01

    A method for passivating compound semiconductor surfaces by photolytically disrupting molecular sulfur vapor with ultraviolet radiation to form reactive sulfur which then reacts with and passivates the surface of compound semiconductors.

  7. Active Flow Control Strategies Using Surface Pressure Measurements

    NASA Technical Reports Server (NTRS)

    Kumar, Vikas; Alvi, Farrukh S.

    2010-01-01

    Evaluate the efficacy of Microjets Can we eliminate/minimize flow separation? Is the flow unsteadiness reduced? Guidelines for an active control Search for an appropriate sensor. Examine for means to develop a flow model for identifying the state of flow over the surface Guidelines toward future development of a Simple and Robust control methodology

  8. Micro-structuring of polycarbonate-urethane surfaces in order to reduce platelet activation and adhesion.

    PubMed

    Clauser, Johanna; Gester, Kathrin; Roggenkamp, Jan; Mager, Ilona; Maas, Judith; Jansen, Sebastian V; Steinseifer, Ulrich

    2014-01-01

    In the development of new hemocompatible biomaterials, surface modification appears to be a suitable method in order to reduce the thrombogenetic potential of such materials. In this study, polycarbonate-urethane (PCU) tubes with different surface microstructures to be used for aortic heart valve models were investigated with regard to the thrombogenicity. The surface structures were produced by using a centrifugal casting process for manufacturing PCU tubes with defined casting mold surfaces which are conferred to the PCU surface during the process. Tubes with different structures defined by altering groove widths were cut into films and investigated under dynamic flow conditions in contact with porcine blood. The analysis was carried out by laser scanning microscopy which allowed for counting various morphological types of platelets with regard to the grade of activation. The comparison between plain and shaped PCU samples showed that the surface topography led to a decline of the activation of the coagulation cascade and thus to the reduction of the fibrin synthesis. Comparing different types of structures revealed that smooth structures with a small groove width (d ~ 3 μm) showed less platelet activation as well as less adhesion in contrast to a distinct wave structure (d ~ 90 μm). These results prove surface modification of polymer biomaterials to be a suitable method for reducing thrombogenicity and hence give reason for further alterations and improvements.

  9. Patched bimetallic surfaces are active catalysts for ammonia decomposition

    SciTech Connect

    Guo, Wei; Vlachos, Dionisios G.

    2015-10-07

    In this study, ammonia decomposition is often used as an archetypical reaction for predicting new catalytic materials and understanding the very reason of why some reactions are sensitive on material’s structure. Core–shell or surface-segregated bimetallic nanoparticles expose outstanding activity for many heterogeneously catalysed reactions but the reasons remain elusive owing to the difficulties in experimentally characterizing active sites. Here by performing multiscale simulations in ammonia decomposition on various nickel loadings on platinum (111), we show that the very high activity of core–shell structures requires patches of the guest metal to create and sustain dual active sites: nickel terraces catalyse N-H bond breaking and nickel edge sites drive atomic nitrogen association. The structure sensitivity on these active catalysts depends profoundly on reaction conditions due to kinetically competing relevant elementary reaction steps. We expose a remarkable difference in active sites between transient and steady-state studies and provide insights into optimal material design.

  10. The influence of badland surfaces and erosion processes on vegetation cover

    NASA Astrophysics Data System (ADS)

    Hardenbicker, Ulrike; Matheis, Sarah

    2014-05-01

    less dense pioneer vegetation consisting of grasses and sage bushes indicating minimal surface erosion or sedimentation. Geomorphic mapping documented a high density of active pipes in this area, transporting silt and fine sand from the sandstone cliffs to lower and basal pediments. Vegetation cover alone is a poor indicator of badland surfaces and erosion processes because of the three-dimensional nature of badland erosion processes, and the shrink-swell capacity of the bentonitic bedrock. A combination of geomorphic and vegetation mapping is needed to identify badland surfaces and processes in the study area.

  11. Effect of Surface Engineering Processes on the Surface Properties and Adhesive Bonding of Graphite/Epoxy Composites (Preprint)

    DTIC Science & Technology

    2007-12-01

    chemistry significantly by removing contaminants such as mold release agents and introducing free radicals as a result of fracture processes. Surface...aluminum foil and cut into 18 x 8 mm samples with a hacksaw. Dust from the cutting process was removed by blowing the sample surfaces with compressed...probably related to a filler. Although the surfaces of similarly prepared composites are usually contaminated with fluorine characteristic of mold

  12. Publications of the Western Earth Surface Processes Team, 1999

    USGS Publications Warehouse

    Stone, Paul; Powell, Charles L.

    2000-01-01

    The Western Earth Surfaces Processes Team (WESPT) of the U.S. Geological Survey, Geologic Division (USGS, GD), conducts geologic mapping and related topical earth- science studies in the western United States. This work is focused on areas where modern geologic maps and associated earth-science data are needed to address key societal and environmental issues such as ground-water quality, potential geologic hazards, and land-use decisions. Areas of primary emphasis currently include southern California, the San Francisco Bay region, and the Pacific Northwest. The team has its headquarters in Menlo Park, California, and maintains field offices at several other locations in the western United States. The results of research conducted by the WESPT are released to the public as a variety of databases, maps, text reports, and abstracts, both through the internal publication system of the USGS and in diverse external publications such as scientific journals and books. This report lists publications of the WESPT released in 1999 as well as additional 1997 and 1998 publications that were not included in the previous list (USGS Open-file Report 99-302). Most of the publications listed were authored or coauthored by WESPT staff. The list also includes some publications authored by non-USGS cooperators with the WESPT, as well as some authored by USGS staff outside the WESPT in cooperation with WESPT projects.

  13. 40 CFR 63.134 - Process wastewater provisions-surface impoundments.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 10 2012-07-01 2012-07-01 false Process wastewater provisions-surface... Manufacturing Industry for Process Vents, Storage Vessels, Transfer Operations, and Wastewater § 63.134 Process wastewater provisions—surface impoundments. (a) For each surface impoundment that receives, manages,...

  14. 40 CFR 63.134 - Process wastewater provisions-surface impoundments.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Process wastewater provisions-surface... Manufacturing Industry for Process Vents, Storage Vessels, Transfer Operations, and Wastewater § 63.134 Process wastewater provisions—surface impoundments. (a) For each surface impoundment that receives, manages,...

  15. 40 CFR 63.134 - Process wastewater provisions-surface impoundments.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 10 2013-07-01 2013-07-01 false Process wastewater provisions-surface... Manufacturing Industry for Process Vents, Storage Vessels, Transfer Operations, and Wastewater § 63.134 Process wastewater provisions—surface impoundments. (a) For each surface impoundment that receives, manages,...

  16. 40 CFR 63.134 - Process wastewater provisions-surface impoundments.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 9 2011-07-01 2011-07-01 false Process wastewater provisions-surface... Manufacturing Industry for Process Vents, Storage Vessels, Transfer Operations, and Wastewater § 63.134 Process wastewater provisions—surface impoundments. (a) For each surface impoundment that receives, manages,...

  17. 40 CFR 63.134 - Process wastewater provisions-surface impoundments.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 10 2014-07-01 2014-07-01 false Process wastewater provisions-surface... Manufacturing Industry for Process Vents, Storage Vessels, Transfer Operations, and Wastewater § 63.134 Process wastewater provisions—surface impoundments. (a) For each surface impoundment that receives, manages,...

  18. Controlling hydrogenation activity and selectivity of bimetallic surfaces and catalysts

    NASA Astrophysics Data System (ADS)

    Murillo, Luis E.

    Studies of bimetallic systems are of great interest in catalysis due to the novel properties that they often show in comparison with the parent metals. The goals of this dissertation are: (1) to expand the studies of self-hydrogenation and hydrogenation reactions on bimetallic surfaces under ultra high vacuum conditions (UHV) using different hydrocarbon as probe molecules; (2) to attempt to correlate the surface science findings with supported catalyst studies under more realistic conditions; and (3) to investigate the competitive hydrogenation of C=C versus C=O bonds on Pt(111) modified by different 3d transition metals. Hydrogenation studies using temperature programmed desorption (TPD) on Ni/Pt(111) bimetallic surfaces have demonstrated an enhancement in the low temperature hydrogenation activity relative to that of clean Pt(111). This novel hydrogenation pathway can be achieved under UHV conditions by controlling the structures of the bimetallic surfaces. A low temperature hydrogenation activity of 1-hexene and 1-butene has been observed on a Pt-Ni-Pt(111) subsurface structure, where Ni atoms are mainly present on the second layer of the Pt(111) single crystal. These results are in agreement with previous studies of self-hydrogenation and hydrogenation of cyclohexene. However, a much higher dehydrogenation activity is observed in the reaction of cyclohexene to produce benzene, demonstrating that the hydrocarbon structure has an effect on the reaction pathways. On the other hand, self-hydrogenation of 1-butene is not observed on the Pt-Ni-Pt(111) surface, indicating that the chain length (or molecular weight) has a significant effect on the selfhydrogenation activity. The gas phase reaction of cyclohexene on Ni/Pt supported on alumina catalysts has also shown a higher self-hydrogenation activity in comparison with the same reaction performed on supported monometallic catalysts. The effects of metal loading and impregnation sequence of the metal precursors are

  19. Surface Characteristics of Titanium during ECM Process for Biomedical Applications

    SciTech Connect

    Dhobe, Shirish D.; Doloi, B.; Bhattacharyya, B.

    2011-01-17

    Electrochemical machining is described as the controlled removal of metal by anodic dissolution of the workpiece in electrolyte cell. Titanium is extensively used in aerospace, defence, biomedical applications. The human response to implanted titanium parts strongly related to the implant surface conditions. The aim of this paper is to present experimental investigation on electrochemically machined surface characteristics acquired on titanium, utilizing developed cross flow electrolyte system. It is observed that applied voltage and electrolyte flow rate are the some of the persuading parameter to attain desired surface characteristics on machined surface. Attempt has made to develop surface along with self-generated oxide layer, which facilitates in improving the corrosion and chemical resistance of titanium implant in biomedical application. The surface roughness of oxide layered machined surface obtained within 2.4 {mu}m to 2.93 {mu}m, which is within acceptable value for functional attachment between bone and implant.

  20. Application of modern surface analytical tools in the investigation of surface deterioration processes

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1983-01-01

    Surface profilometry and scanning electron microscopy were utilized to study changes in the surface of polymers when eroded. The X-ray photoelectron spectroscopy (XPS) and depth profile analysis indicate the corrosion of metal and ceramic surfaces and reveal the diffusion of certain species into the surface to produce a change in mechanical properties. Ion implantation, nitriding and plating and their effects on the surface are characterized. Auger spectroscopy analysis identified morphological properties of coatings applied to surfaces by sputter deposition.

  1. Preferences for Deep-Surface Learning: A Vocational Education Case Study Using a Multimedia Assessment Activity

    ERIC Educational Resources Information Center

    Hamm, Simon; Robertson, Ian

    2010-01-01

    This research tests the proposition that the integration of a multimedia assessment activity into a Diploma of Events Management program promotes a deep learning approach. Firstly, learners' preferences for deep or surface learning were evaluated using the revised two-factor Study Process Questionnaire. Secondly, after completion of an assessment…

  2. Surface modification processes during methane decomposition on Cu-promoted Ni–ZrO2 catalysts

    PubMed Central

    Wolfbeisser, Astrid; Klötzer, Bernhard; Mayr, Lukas; Rameshan, Raffael; Zemlyanov, Dmitry; Bernardi, Johannes; Rupprechter, Günther

    2015-01-01

    The surface chemistry of methane on Ni–ZrO2 and bimetallic CuNi–ZrO2 catalysts and the stability of the CuNi alloy under reaction conditions of methane decomposition were investigated by combining reactivity measurements and in situ synchrotron-based near-ambient pressure XPS. Cu was selected as an exemplary promoter for modifying the reactivity of Ni and enhancing the resistance against coke formation. We observed an activation process occurring in methane between 650 and 735 K with the exact temperature depending on the composition which resulted in an irreversible modification of the catalytic performance of the bimetallic catalysts towards a Ni-like behaviour. The sudden increase in catalytic activity could be explained by an increase in the concentration of reduced Ni atoms at the catalyst surface in the active state, likely as a consequence of the interaction with methane. Cu addition to Ni improved the desired resistance against carbon deposition by lowering the amount of coke formed. As a key conclusion, the CuNi alloy shows limited stability under relevant reaction conditions. This system is stable only in a limited range of temperature up to ~700 K in methane. Beyond this temperature, segregation of Ni species causes a fast increase in methane decomposition rate. In view of the applicability of this system, a detailed understanding of the stability and surface composition of the bimetallic phases present and the influence of the Cu promoter on the surface chemistry under relevant reaction conditions are essential. PMID:25815163

  3. Electrochemical decolorization of dye wastewater by surface-activated boron-doped nanocrystalline diamond electrode.

    PubMed

    Chen, Chienhung; Nurhayati, Ervin; Juang, Yaju; Huang, Chihpin

    2016-07-01

    Complex organics contained in dye wastewater are difficult to degrade and often require electrochemical advanced oxidation processes (EAOPs) to treat it. Surface activation of the electrode used in such treatment is an important factor determining the success of the process. The performance of boron-doped nanocrystalline diamond (BD-NCD) film electrode for decolorization of Acid Yellow (AY-36) azo dye with respect to the surface activation by electrochemical polarization was studied. Anodic polarization found to be more suitable as electrode pretreatment compared to cathodic one. After anodic polarization, the originally H-terminated surface of BD-NCD was changed into O-terminated, making it more hydrophilic. Due to the oxidation of surface functional groups and some portion of sp(2) carbon in the BD-NCD film during anodic polarization, the electrode was successfully being activated showing lower background current, wider potential window and considerably less surface activity compared to the non-polarized one. Consequently, electrooxidation (EO) capability of the anodically-polarized BD-NCD to degrade AY-36 dye was significantly enhanced, capable of nearly total decolorization and chemical oxygen demand (COD) removal even after several times of re-using. The BD-NCD film electrode favored acidic condition for the dye degradation; and the presence of chloride ion in the solution was found to be more advantageous than sulfate active species.

  4. Preparation of sulfurized powdered activated carbon from waste tires using an innovative compositive impregnation process.

    PubMed

    Yuan, Chung-Shin; Lin, Hsun-Yu; Wu, Chun-Hsin; Liu, Ming-Han; Hung, Chung-Hsuang

    2004-07-01

    The objective of this study is to develop an innovative compositive impregnation process for preparing sulfurized powdered activated carbon (PAC) from waste tires. An experimental apparatus, including a pyrolysis and activation system and a sulfur (S) impregnation system, was designed and applied to produce sulfurized PAC with a high specific surface area. Experimental tests involved the pyrolysis, activation, and sulfurization of waste tires. Waste-tire-derived PAC (WPAC) was initially produced in the pyrolysis and activation system. Experimental results indicated that the Brunauer-Emmett-Teller (BET) surface area of WPAC increased, and the average pore radius of WPAC decreased, as water feed rate and activation time increased. In this study, a conventional direct impregnation process was used to prepare the sulfurized PAC by impregnating WPAC with sodium sulfide (Na2S) solution. Furthermore, an innovative compositive impregnation process was developed and then compared with the conventional direct impregnation process. Experimental results showed that the compositive impregnation process produced the sulfurized WPAC with high BET surface area and a high S content. A maximum BET surface area of 886 m2/g and the S content of 2.61% by mass were obtained at 900 degrees C and at the S feed ratio of 2160 mg Na2S/g C. However, the direct impregnation process led to a BET surface area of sulfurized WPAC that decreased significantly as the S content increased.

  5. Gold surface with gold nitride-a surface enhanced Raman scattering active substrate

    NASA Astrophysics Data System (ADS)

    Brieva, A. C.; Alves, L.; Krishnamurthy, S.; Šiller, L.

    2009-03-01

    The nitration of gold surfaces is a nonpolluting method, which can lead to large scale production of substrates with remarkable properties and applications. We present a topographical study of the nanoscale structure of the gold nitride surfaces produced by radio frequency (rf) nitrogen plasma etching of thin gold films. Atomic force microscopy images taken after rf etching reveal the striking appearance of the cluster assembly with large clusters surrounded by small clusters (7.9±1.4 and 2.3±0.9 nm, respectively) appearing to exhibit an attractive interaction. We discuss the possible mechanism for this attraction based on a colloid model by Messina et al. [Phys. Rev. Lett. 85, 872 (2000)]. This surface exhibits a notable surface enhanced Raman scattering effect demonstrated with L-alanine and rhodamine-6G. The significance of this work is that we found that this SERS active gold nitride surface can be prepared in just one step: by nitrogen plasma etching a thin gold film. Until now most SERS active gold cluster covered surfaces have been prepared in several steps very often requiring complex lithography.

  6. Partial difference operators on weighted graphs for image processing on surfaces and point clouds.

    PubMed

    Lozes, Francois; Elmoataz, Abderrahim; Lezoray, Olivier

    2014-09-01

    Partial difference equations (PDEs) and variational methods for image processing on Euclidean domains spaces are very well established because they permit to solve a large range of real computer vision problems. With the recent advent of many 3D sensors, there is a growing interest in transposing and solving PDEs on surfaces and point clouds. In this paper, we propose a simple method to solve such PDEs using the framework of PDEs on graphs. This latter approach enables us to transcribe, for surfaces and point clouds, many models and algorithms designed for image processing. To illustrate our proposal, three problems are considered: (1) p -Laplacian restoration and inpainting; (2) PDEs mathematical morphology; and (3) active contours segmentation.

  7. Absolute height measurement of specular surfaces with modified active fringe reflection photogrammetry

    NASA Astrophysics Data System (ADS)

    Ren, Hongyu; Jiang, Xiangqian; Gao, Feng; Zhang, Zonghua

    2014-07-01

    Deflectometric methods have been studied for more than a decade for slope measurement of specular freeform surfaces through utilization of the deformation of a sample pattern after reflection from a tested sample surface. Usually, these approaches require two-directional fringe patterns to be projected on a LCD screen or ground glass and require slope integration, which leads to some complexity for the whole measuring process. This paper proposes a new mathematical measurement model for measuring topography information of freeform specular surfaces, which integrates a virtual reference specular surface into the method of active fringe reflection photogrammetry and presents a straight-forward relation between height of the tested surface and phase signals. This method only requires one direction of horizontal or vertical sinusoidal fringe patterns to be projected from a LCD screen, resulting in a significant reduction in capture time over established methods. Assuming the whole system has been precalibrated during the measurement process, the fringe patterns are captured separately via the virtual reference and detected freeform surfaces by a CCD camera. The reference phase can be solved according to the spatial geometric relation between the LCD screen and the CCD camera. The captured phases can be unwrapped with a heterodyne technique and optimum frequency selection method. Based on this calculated unwrapped-phase and that proposed mathematical model, absolute height of the inspected surface can be computed. Simulated and experimental results show that this methodology can conveniently calculate topography information for freeform and structured specular surfaces without integration and reconstruction processes.

  8. Effect of sulfation on the surface activity of CaO for N2O decomposition

    NASA Astrophysics Data System (ADS)

    Wu, Lingnan; Hu, Xiaoying; Qin, Wu; Dong, Changqing; Yang, Yongping

    2015-12-01

    Limestone addition to circulating fluidized bed boilers for sulfur removal affects nitrous oxide (N2O) emission at the same time, but mechanism of how sulfation process influences the surface activity of CaO for N2O decomposition remains unclear. In this paper, we investigated the effect of sulfation on the surface properties and catalytic activity of CaO for N2O decomposition using density functional theory calculations. Sulfation of CaO (1 0 0) surface by the adsorption of a single gaseous SO2 or SO3 molecule forms stable local CaSO3 or CaSO4 on the CaO (1 0 0) surface with strong hybridization between the S atom of SOx and the surface O anion. The formed local CaSO3 increases the barrier energy of N2O decomposition from 0.989 eV (on the CaO (1 0 0) surface) to 1.340 eV, and further sulfation into local CaSO4 remarkably increases the barrier energy to 2.967 eV. Sulfation from CaSO3 into CaSO4 is therefore the crucial step for deactivating the surface activity for N2O decomposition. Completely sulfated CaSO4 (0 0 1) and (0 1 0) surfaces further validate the negligible catalytic ability of CaSO4 for N2O decomposition.

  9. Tunneling Microscopy of Dynamical Processes on the LEAD/GERMANIUM(111) Surface

    NASA Astrophysics Data System (ADS)

    Hwang, Ing-Shouh

    Knowledge about atomic scale motions is essential for understanding dynamical phenomena on surfaces, such as diffusion, phase transitions, and epitaxial growth. This report describes the results of a study of dynamical processes on the Pb/Ge(111) surface using a scanning tunneling microscope (STM). Individual Pb atom diffUsion and concerted atomic motions on the Ge(111) surface are observed in real time. We also study a structural surface phase transformation at elevated temperatures. At very low Pb coverage, migration of individual Pb atoms is observed in the Ge(111)-c(2 x 8) surface near room temperature. The activation energy of this migration can be measured by analyzing a large number of individual atomic motions from room temperature to 80^ circC. The Pb diffusion is found to occur mainly along the (011) adatom row direction of the c(2 x 8) reconstruction. About half of the adatom migrations are "long jumps". We also observe the formation and annihilation of metastable structural surface excitations, which occur much less often than Pb diffusion. They involve a number of adatoms in the same row moving in concert along the row direction like beads on an abacus. This "adatom row shift" may be responsible for the anisotropy of the Pb atom diffusion. It also provides a new mechanism for atomic transport on crystal surfaces and can explain several structural phenomena associated with the Ge(111) surface. At high coverage, a one monolayer Pb/Ge(111) undergoes a reversible phase transformation from sqrt{3} x sqrt{3 }R30^circ to 1 x 1 at about 180 ^circC. Atomic structures of both high and low temperature phases are resolved, which reveals an order-order transition. Spatial and temporal fluctuations are exposed just above the transition temperature. In addition, the influence of surface strain, phase boundaries, and finite size domains are found to play an important role in the phase transformation.

  10. Total pollen counts do not influence active surface measurements

    NASA Astrophysics Data System (ADS)

    Moshammer, Hanns; Schinko, Herwig; Neuberger, Manfred

    We investigated the temporal association of various aerosol parameters with pollen counts in the pollen season (April 2001) in Linz, Austria. We were especially interested in the relationship between active surface (or Fuchs' surface) because we had shown previously (Atmos. Environ. 37 (2003) 1737-1744) that this parameter during the same observation period was a better predictor for acute respiratory symptoms in school children (like wheezing, shortness of breath, and cough) and reduced lung function on the same day than particle mass (PM 10). While active surface is most sensitive for fine particles with a diameter of less than 100 nm it has no strict upper cut-off regarding particle size and so could eventually be influenced also by larger particles if their numbers were high. All particle mass parameters tested (TSP, PM 10, PM 1) were weakly ( r approximately 0.2) though significantly correlated with pollen counts but neither was active surface nor total particle counts (CPC). The weak association of particle mass and pollen counts was due mainly to similar diurnal variations and a linear trend over time. Only the mass of the coarse fraction (TSP minus PM 10) remained associated with pollen counts significantly after controlling for these general temporal patterns.

  11. Coat formation of surface-active proteins on aqueous surfaces during drying.

    PubMed

    Nijdam, J; Trouillet, V; Kachel, S; Scharfer, P; Schabel, W; Kind, M

    2014-11-01

    Segregation of the protein bovine serum albumin (BSA) and lactose in thin aqueous films during drying was investigated by examining the composition of the dried films using inverse micro Raman spectroscopy (IMRS) and X-ray photoelectron spectroscopy (XPS) sputter-depth profiling. The composition was uniform through the thickness of the dried films except within a 10nm region at the exposed surface where BSA had accumulated, most likely due to its surface activity. The thickness of the BSA layer was similar to the diameter of a BSA molecule, which suggests that a single monolayer of BSA adsorbed at the exposed surface. The BSA surface concentration of the dried films was constant over a wide range of BSA bulk concentrations, indicating that the aqueous surface became saturated with BSA during drying. The BSA surface layer of order 10nm was significantly thinner than the film thickness of order 10 μm, which implies that BSA formed a surface coating rather than a shell, and thus lent no structural rigidity to the film.

  12. Surface active complexes formed between keratin polypeptides and ionic surfactants.

    PubMed

    Pan, Fang; Lu, Zhiming; Tucker, Ian; Hosking, Sarah; Petkov, Jordan; Lu, Jian R

    2016-12-15

    Keratins are a group of important proteins in skin and hair and as biomaterials they can provide desirable properties such as strength, biocompatibility, and moisture regaining and retaining. The aim of this work is to develop water-soluble keratin polypeptides from sheep wool and then explore how their surface adsorption behaves with and without surfactants. Successful preparation of keratin samples was demonstrated by identification of the key components from gel electrophoresis and the reproducible production of gram scale samples with and without SDS (sodium dodecylsulphate) during wool fibre dissolution. SDS micelles could reduce the formation of disulphide bonds between keratins during extraction, reducing inter-molecular crosslinking and improving keratin polypeptide solubility. However, Zeta potential measurements of the two polypeptide batches demonstrated almost identical pH dependent surface charge distributions with isoelectric points around pH 3.5, showing complete removal of SDS during purification by dialysis. In spite of different solubility from the two batches of keratin samples prepared, very similar adsorption and aggregation behavior was revealed from surface tension measurements and dynamic light scattering. Mixing of keratin polypeptides with SDS and C12TAB (dodecyltrimethylammonium bromide) led to the formation of keratin-surfactant complexes that were substantially more effective at reducing surface tension than the polypeptides alone, showing great promise in the delivery of keratin polypeptides via the surface active complexes. Neutron reflection measurements revealed the coexistence of surfactant and keratin polypeptides at the interface, thus providing the structural support to the observed surface tension changes associated with the formation of the surface active complexes.

  13. Activating piezoelectric crystal surface by silanization for microgravimetric immunobiosensor application.

    PubMed

    Suri, C R; Mishra, G C

    1996-01-01

    The development of a microgravimetric immunobiosensor using a piezoelectric quartz crystal as a detector requires a stable and reproducible immobilization method for ligand binding. The method of silanization using 3-aminopropyltriethoxysilane (APTES) has been widely used for activating the carrier surface. In the present study, APTES deposition on a piezoelectric crystal surface was studied under various solvent conditions. A fluorescence method, using fluorescence isothiocyanate as a dye, was demonstrated for the quantification of amino groups on the silanized piezoelectric crystal surface. The optimum binding conditions of APTES deposition on a piezoelectric crystal surface were incorporated for the covalent immobilization of protein on the crystal surface in developing a stable and sensitive microgravimetric immunobiosensor. Determination of immunoglobulin G (IgG) concentration was performed using APTES modified piezoelectric crystals coated with protein G. The resonant frequency shift, resulting from the formation of protein G-IgG complex on the crystal surface, correlated with the concentration of IgG in the range 10 ng/ml to 0.1 mg/ml. The APTES modified, protein G coated crystal were found to be quite stable and did not show a significant loss of sensitivity even after 12 weeks of storage at 4 degrees C in a desiccator.

  14. Study on the oxidation and reduction of tungsten surface for sub-50 nm patterning process

    SciTech Connect

    Kim, Jong Kyu; Nam, Seok Woo; Cho, Sung Il; Jhon, Myung S.; Min, Kyung Suk; Kim, Chan Kyu; Jung, Ho Bum; Yeom, Geun Young

    2012-11-15

    The oxidation characteristics of tungsten line pattern during the carbon-based mask-layer removal process using oxygen plasmas have been investigated for sub-50 nm patterning processes, in addition to the reduction characteristics of the WO{sub x} layer formed on the tungsten line surface using hydrogen plasmas. The surface oxidation of tungsten lines during the mask layer removal process could be minimized by using low-temperature (300 K) plasma processing for the removal of the carbon-based material. Using this technique, the thickness of WO{sub x} on the tungsten line could be decreased to 25% compared to results from high-temperature processing. The WO{sub x} layer could also be completely removed at a low temperature of 300 K using a hydrogen plasma by supplying bias power to the tungsten substrate to provide a activation energy for the reduction. When this oxidation and reduction technique was applied to actual 40-nm-CD device processing, the complete removal of WO{sub x} formed on the sidewall of tungsten line could be observed.

  15. Surface Photometry of Reverberation-Mapped Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Bower, Gary A.

    2015-01-01

    I present a statistical analysis of the surface photometry obtained for a sample of Hubble Space Telescope (HST) archival images of the host galaxies containing active galactic nuclei (AGN), whose time-delay between continuum and broad emission line variations have been analyzed (i.e., reverberation mapping). For quiescent galaxies, strong correlations exist between central black hole mass and host galaxy structure. If there are similar correlations for AGN between central black hole masses derived from reverberation mapping and the host galaxy structure that I have derived from archival HST images, this would imply some validation of the assumptions underlying reverberation mapping concerning the structure, kinematics, and orientation of the broad line regions in AGN.The correlations for quiescent galaxies bewteen central black hole mass and host galaxy structure imply that there might be a strong causal connection between the formation and evolution of the black hole and the galaxy bulge. A current hypothesis is that bulges, black holes, and quasars formed, grew, or turned on as parts of the same process, in part because the collapse or merger of bulges might provide a rich fuel supply to a central black hole. One way of testing this hypothesis would be to plot AGN as a function of redshift on these correlations. However, two severe obstacles limit the ability to measure black hole masses in AGN using HST to analyze the central stellar and/or gas dynamics: (1) since spatial resolution becomes more limited at larger distances, only two reverberation-mapped AGN are close enough to Earth to render the analysis feasible, and (2) it isdifficult to obtain useful spectra of the stars and/or gas in the presence of the bright nonstellar nucleus. The most useful alternative is to exploit reverberation mapping, which uses the time delay in a given AGN between variations in the continuum emission and broad emission lines.

  16. Application of surface area measurement for identifying the source of batch-to-batch variation in processability.

    PubMed

    Vippagunta, Radha R; Pan, Changkang; Vakil, Ronak; Meda, Vindhya; Vivilecchia, Richard; Motto, Michael

    2009-01-01

    The primary goal of this study was to evaluate the use of specific surface area as a measurable physical property of materials for understanding the batch-to-batch variation in the flow behavior. The specific surface area measurements provide information about the nature of the surface making up the solid, which may include defects or void space on the surface. These void spaces are often present in the crystalline material due to varying degrees of disorderness and can be considered as amorphous regions. In the present work, the specific surface area for 10 batches of the same active pharmaceutical ingredient (compound 1) with varying quantity of amorphous content was investigated. Some of these batches showed different flow behavior when processed using roller compaction. The surface area value was found to increase in the presence of low amorphous content, and decrease with high amorphous content as compared to crystalline material. To complement the information obtained from the above study, physical blends of another crystalline active pharmaceutical ingredient (compound 2) and its amorphous form were prepared in known proportions. Similar trend in specific surface area value was found. Tablets prepared from known formulation with varying amorphous content of the active ingredient (compound 3) also exhibited the same trend. A hypothesis to explain the correlation between the amorphous content and specific surface area has been proposed. The results strongly support the use of specific surface area as a measurable tool for investigation of source of batch to batch variation in processability.

  17. Understanding the creation of & reducing surface microroughness during polishing & post-processing of glass optics

    SciTech Connect

    Suratwala, Tayyab

    2016-09-22

    In the follow study, we have developed a detailed understanding of the chemical and mechanical microscopic interactions that occur during polishing affecting the resulting surface microroughness of the workpiece. Through targeted experiments and modeling, the quantitative relationships of many important polishing parameters & characteristics affecting surface microroughness have been determined. These behaviors and phenomena have been described by a number of models including: (a) the Ensemble Hertzian Multi Gap (EHMG) model used to predict the removal rate and roughness at atomic force microscope (AFM) scale lengths as a function of various polishing parameters, (b) the Island Distribution Gap (IDG) model used to predict the roughness at larger scale lengths, (c) the Deraguin-Verwey-Landau-Overbeek (DLVO) 3-body electrostatic colloidal model used to predict the interaction of slurry particles at the interface and roughness behavior as a function of pH, and (d) a diffusion/chemical reaction rate model of the incorporation of impurities species into the polishing surface layer (called the Bielby layer). Based on this improved understanding, novel strategies to polish the workpiece have been developed simultaneously leading to both ultrasmooth surfaces and high material removal rates. Some of these strategies include: (a) use of narrow PSD slurries, (b) a novel diamond conditioning recipe of the lap to increase the active contact area between the workpiece and lap without destroying its surface figure, (c) proper control of pH for a given glass type to allow for a uniform distribution of slurry particles at the interface, and (d) increase in applied load just up to the transition between molecular to plastic removal regime for a single slurry particle. These techniques have been incorporated into a previously developed finishing process called Convergent Polishing leading to not just economical finishing process with improved surface figure control, but also

  18. Land-surface processes and monsoon climate system

    NASA Astrophysics Data System (ADS)

    Xue, Y.

    2014-12-01

    Differential thermal heating of land and ocean and heat release into the atmosphere are important factors that determine the onset, strength, duration and spatial distribution of large-scale monsoons. A global and seasonal assessment of land surface process (LSP) effects on the monsoon system has been made based on general circulation models (GCM) coupled to different benchmark land models, which physically represent either comprehensive, or partial, or minimal LSP representations. Observed precipitation is applied as constrain and differences in simulation error are used to assess the effect of the LSP with different complexity. The AGCM results indicate that the land/atmosphere interaction has substantial impact on global water cycle, while the monsoon regions have had strongest impact at intraseasonal to decadal scales. Among monsoon regions, West Africa, South Asia, East Asia, and Amazon regions have largest impact while some monsoon regions have less impact due to strong air/sea interactions and narrow land mass. LSP reduces the annual precipitation error by 58% over global monsoon regions, about 35% observed precipitation. The partial LSP effect (excluding soil moisture and vegetation albedo) reduces annual precipitation error over monsoon region that equals to about 13% of observed precipitation. It has also been suggested that LSP contribute to the abrupt jump in latitude of the East Asian monsoon as well as general circulation turning in some monsoon regions in its early stages. The LSP effects have also been assessed in the land use land cover change experiment. Based on recently compiled global land-use data from 1948-2005, the GCM simulation results indicate the degradation in Mexico, West Africa, south and East Asia and South America produce substantial precipitation anomalies, some of which are consistent with observed regional precipitation anomalies. More comprehensive studies with multi-models are imperatively necessary.

  19. Publications of the Western Earth Surface Processes Team 2000

    USGS Publications Warehouse

    Powell, Charles L.; Stone, Paul

    2001-01-01

    The Western Earth Surface Processes Team (WESP) of the U.S. Geological Survey (USGS) conducts geologic mapping and related topical earth science studies in the western United States. This work is focused on areas where modern geologic maps and associated earth-science data are needed to address key societal and environmental issues such as ground-water quality, potential geologic hazards, and land-use decisions. Areas of primary emphasis in 2000 included southern California, the San Francisco Bay region, the Pacific Northwest, the Las Vegas urban corridor, and selected National Park lands. The team has its headquarters in Menlo Park, California, and maintains smaller field offices at several other locations in the western United States. The results of research conducted by the WESPT are released to the public as a variety of databases, maps, text reports, and abstracts, both through the internal publication system of the USGS and in diverse external publications such as scientific journals and books. This report lists publications of the WESPT released in 2000 as well as additional 1999 publications that were not included in the previous list (USGS Open-file Report 00-215). Most of the publications listed were authored or coauthored by WESPT staff. The list also includes some publications authored by non-USGS cooperators with the WESPT, as well as some authored by USGS staff outside the WESPT in cooperation with WESPT projects. Several of the publications listed are available on the World Wide Web; for these, URL addresses are provided. Many of these Web publications are USGS open-file reports that contain large digital databases of geologic map and related information.

  20. Publications of Western Earth Surface Processes Team 2001

    USGS Publications Warehouse

    Powell, II; Graymer, R.W.

    2002-01-01

    The Western Earth Surface Processes Team (WESPT) of the U.S. Geological Survey (USGS) conducts geologic mapping and related topical earth-science studies in the Western United States. This work is focused on areas where modern geologic maps and associated earth-science data are needed to address key societal and environmental issues, such as ground-water quality, landslides and other potential geologic hazards, and land-use decisions. Areas of primary emphasis in 2001 included southern California, the San Francisco Bay region, the Pacific Northwest, and the Las Vegas urban corridor. The team has its headquarters in Menlo Park, California, and maintains smaller field offices at several other locations in the Western United States. The results of research conducted by the WESPT are released to the public as a variety of databases, maps, text reports, and abstracts, both through the internal publication system of the USGS and in diverse external publications such as scientific journals and books. This report lists publications of the WESPT released in 2001, as well as additional 1999 and 2000 publications that were not included in the previous list (USGS Open-File Report 00–215 and USGS Open-File Report 01–198). Most of the publications listed were authored or coauthored by WESPT staff. The list also includes some publications authored by non-USGS cooperators with the WESPT, as well as some authored by USGS staff outside the WESPT in cooperation with WESPT projects. Several of the publications listed are available on the World Wide Web; for these, URL addresses are provided. Many of these web publications are USGS Open-File Reports that contain large digital databases of geologic map and related information.

  1. Characterization of surface processes on mineral surfaces in aqueous solutions. Annual report for fiscal year 1993

    SciTech Connect

    Leckie, J.O.

    1993-11-01

    Performance assessments by Los Alamos National Laboratory for the DOE`s Yucca Mountain Site Characterization Project (YMP) are being done investigating the environmental risk related to long-term disposal of hazardous wastes resulting from the use of radioactive materials that must subsequently be isolated from the environment. The YMP site, located in southwestern Nevada, is intended for the storage of high-level wastes generated by nuclear energy-related activities, including spent fuel and waste from reprocessed fuel rods. The work covered by this contract is necessary for producing a defensible model and dataset, and may be critical for evaluation of repository compliance. This work, performed by the Environmental Engineering and Science research group at Stanford University, will quantify the adsorption of uranyl on various minerals. The project`s principle objective is to provide sorption coefficients for uranyl and other ions of interest to predict radionuclide movements form the repository to accessible environments. This adsorption data is essential for the unambiguous interpretation of field experiments and observations. In this report, details of the activity and progress made with respect to the study of uranyl adsorption on mineral surfaces is presented and discussed.

  2. Surface cationized cellulose nanofibrils for the production of contact active antimicrobial surfaces.

    PubMed

    Saini, Seema; Yücel Falco, Çiğdem; Belgacem, Mohamed Naceur; Bras, Julien

    2016-01-01

    In the last decade, a new fiber pretreatment has been proposed to make easy cellulose fibrillation into microfibrils. In this context, different surface cationized MFC was prepared by optimizing the experimental parameters for cellulose fibers pretreatment before fibrillation. All MFCs were characterized by conductometric titration to establish degree of substitution, field emission gun scanning electron microscopy (FEG-SEM), atomic force microscopy (AFM) and optical microscopy assessed the effect of pretreatment on the morphology of the ensuing MFCs. Antibacterial activities of neat and cationized MFC samples were investigated against Gram positive bacteria (Bacillus subtilis, Staphylococcus aureus) and Gram negative bacteria (Escherichia coli). The CATMFC sample at DS greater than 0.18 displayed promising results with antibacterial properties without any leaching of quaternary ammonium into the environment. This work proved the potential of cationic MFCs with specific DS for contact active antimicrobial surface applications in active food packaging, medical packaging or in health and cosmetic field.

  3. Comparative Study of Surface-Active Properties and Antimicrobial Activities of Disaccharide Monoesters

    PubMed Central

    Zhang, Xi; Song, Fei; Taxipalati, Maierhaba; Wei, Wei; Feng, Fengqin

    2014-01-01

    The objective of this research was to determine the effect of sugar or fatty acid in sugar ester compounds on the surface-active properties and antimicrobial activities of these compounds. Disaccharides of medium-chain fatty acid monoesters were synthesized through transesterifications by immobilized lipase (Lipozyme TLIM) to yield nine monoesters for subsequent study. Their antimicrobial activities were investigated using three pathogenic microorganisms: Staphylococcus aureus, Escherichia coli O157:H7 and Candida albicans. Their surface-active properties including air–water surface tension, critical micelle concentration, and foaming and emulsion power and stability were also studied. The results showed that all of the tested monoesters were more effective against Staphylococcus aureus (Gram-positive bacterium) than against Escherichia coli O157:H7 (Gram-negative bacterium). The results demonstrated that the carbon chain length was the most important factor influencing the surface properties, whereas degree of esterification and hydrophilic groups showed little effect. PMID:25531369

  4. Activation studies of NEG coatings by surface techniques

    SciTech Connect

    Sharma, R. K.; Jagannath,; Bhushan, K. G.; Gadkari, S. C.; Mukund, R.; Gupta, S. K.

    2013-02-05

    NEG (Non Evaporable Getters)materials in the form of ternary alloy coatings have many benefits compare to traditional bare surfaces such as Extreme high vacuum(XHV), lower secondary electron yield(SEY), low photon desorption cofficient. The extreme high vacuum (pressure > 10{sup -10} mbar) is very useful to the study of surfaces of the material, for high energy particle accelerators(LHC, Photon Factories), synchrotrons (ESRF, Ellectra) etc. Low secondary electron yield leads to better beam life time. In LHC the pressure in the interaction region of the two beams is something of the order of 10{sup -12} mbar. In this paper preparation of the coatings and their characterization to get the Activation temperature by using the surface techniques XPS, SEM and SIMS has been shown.

  5. Porous Collagen Scaffold Reinforced with Surfaced Activated PLLA Nanoparticles

    PubMed Central

    Xu, Cancan; Lu, Wei; Bian, Shaoquan; Liang, Jie; Fan, Yujiang; Zhang, Xingdong

    2012-01-01

    Porous collagen scaffold is integrated with surface activated PLLA nanoparticles fabricated by lyophilizing and crosslinking via EDC treatment. In order to prepare surface-modified PLLA nanoparticles, PLLA was firstly grafted with poly (acrylic acid) (PAA) through surface-initiated polymerization of acrylic acid. Nanoparticles of average diameter 316 nm and zeta potential −39.88 mV were obtained from the such-treated PLLA by dialysis method. Porous collagen scaffold were fabricated by mixing PLLA nanoparticles with collagen solution, freeze drying, and crosslinking with EDC. SEM observation revealed that nanoparticles were homogeneously dispersed in collagen matrix, forming interconnected porous structure with pore size ranging from 150 to 200 μm, irrespective of the amount of nanoparticles. The porosity of the scaffolds kept almost unchanged with the increment of the nanoparticles, whereas the mechanical property was obviously improved, and the degradation was effectively retarded. In vitro L929 mouse fibroblast cells seeding and culture studies revealed that cells infiltrated into the scaffolds and were distributed homogeneously. Compared with the pure collagen sponge, the number of cells in hybrid scaffolds greatly increased with the increment of incorporated nanoparticles. These results manifested that the surface-activated PLLA nanoparticles effectively reinforced the porous collagen scaffold and promoted the cells penetrating into the scaffold, and proliferation. PMID:22448137

  6. Nanosilver on nanostructured silica: Antibacterial activity and Ag surface area

    PubMed Central

    Sotiriou, Georgios A.; Teleki, Alexandra; Camenzind, Adrian; Krumeich, Frank; Meyer, Andreas; Panke, Sven; Pratsinis, Sotiris E.

    2013-01-01

    Nanosilver is one of the first nanomaterials to be closely monitored by regulatory agencies worldwide motivating research to better understand the relationship between Ag characteristics and antibacterial activity. Nanosilver immobilized on nanostructured silica facilitates such investigations as the SiO2 support hinders the growth of nanosilver during its synthesis and, most importantly, its flocculation in bacterial suspensions. Here, such composite Ag/silica nanoparticles were made by flame spray pyrolysis of appropriate solutions of Ag-acetate or Ag-nitrate and hexamethyldisiloxane or tetraethylorthosilicate in ethanol, propanol, diethylene glucolmonobutyl ether, acetonitrile or ethylhexanoic acid. The effect of solution composition on nanosilver characteristics and antibacterial activity against the Gram negative Escherichia coli was investigated by monitoring their recombinantly synthesized green fluorescent protein. Suspensions with identical Ag mass concentration exhibited drastically different antibacterial activity pointing out that the nanosilver surface area concentration rather than its mass or molar or number concentration determine best its antibacterial activity. Nanosilver made from Ag-acetate showed a unimodal size distribution, while that made from inexpensive Ag-nitrate exhibited a bimodal one. Regardless of precursor composition or nanosilver size distribution, the antibacterial activity of nanosilver was correlated best with its surface area concentration in solution. PMID:23730198

  7. Nanosilver on nanostructured silica: Antibacterial activity and Ag surface area.

    PubMed

    Sotiriou, Georgios A; Teleki, Alexandra; Camenzind, Adrian; Krumeich, Frank; Meyer, Andreas; Panke, Sven; Pratsinis, Sotiris E

    2011-06-01

    Nanosilver is one of the first nanomaterials to be closely monitored by regulatory agencies worldwide motivating research to better understand the relationship between Ag characteristics and antibacterial activity. Nanosilver immobilized on nanostructured silica facilitates such investigations as the SiO2 support hinders the growth of nanosilver during its synthesis and, most importantly, its flocculation in bacterial suspensions. Here, such composite Ag/silica nanoparticles were made by flame spray pyrolysis of appropriate solutions of Ag-acetate or Ag-nitrate and hexamethyldisiloxane or tetraethylorthosilicate in ethanol, propanol, diethylene glucolmonobutyl ether, acetonitrile or ethylhexanoic acid. The effect of solution composition on nanosilver characteristics and antibacterial activity against the Gram negative Escherichia coli was investigated by monitoring their recombinantly synthesized green fluorescent protein. Suspensions with identical Ag mass concentration exhibited drastically different antibacterial activity pointing out that the nanosilver surface area concentration rather than its mass or molar or number concentration determine best its antibacterial activity. Nanosilver made from Ag-acetate showed a unimodal size distribution, while that made from inexpensive Ag-nitrate exhibited a bimodal one. Regardless of precursor composition or nanosilver size distribution, the antibacterial activity of nanosilver was correlated best with its surface area concentration in solution.

  8. An approach for modeling surface reaction kinetics in chemical vapor deposition processes

    SciTech Connect

    Wang, Y.F.; Pollard, R.

    1995-05-01

    A methodology is presented for determining the rate constants of elementary surface reactions that can take place in chemical vapor deposition (CVD) processes. The calculations consider well-defined surfaces that can have one or more dangling bonds at a given site and adsorbates that can take up one or more different bonding configurations. Rate constants for each reaction are obtained independently of any process data using statistical mechanics, transition state theory, and bond dissociation energies. Specifically, the reactions are divided in transition state structures and determine preexponential factors, and the requirement of thermodynamic consistency is used to estimate activation energies. The level of sophistication of the calculations is suitable for treating the large number of plausible steps that could take place in a practical CVD system. Incorporation of the calculated rate constants into a reactor model that includes the effects of fluid flow, transport phenomena, and reactions in the gas and at the growing surface enables dominant reaction pathways and rate-limiting steps to be identified. Moreover, the dependence of growth rate and species compositions on operating conditions can be predicted without fitting any parameters. The utility of the approach is illustrated by modeling low pressure deposition of tungsten from tungsten hexafluoride and silane. This model treats 35 reactions in the gas and 213 reactions at the growing surface. Results are compared with available experimental data and sensitivity studies are used to assess the limitations of the approach.

  9. Laboratory Activities for Developing Process Skills.

    ERIC Educational Resources Information Center

    Institute for Services to Education, Inc., Washington, DC.

    This workbook contains laboratory exercises designed for use in a college introductory biology course. Each exercise helps the student develop a basic science skill. The exercises are arranged in a hierarchical sequence suggesting the scientific method. Each skill facilitates the development of succeeding ones. Activities include Use of the…

  10. Publications of the Western Earth Surface Processes Team 2002

    USGS Publications Warehouse

    Powell, Charles; Graymer, R.W.

    2003-01-01

    The Western Earth Surface Processes Team (WESPT) of the U.S. Geological Survey (USGS) conducts geologic mapping and related topical earth science studies in the western United States. This work is focused on areas where modern geologic maps and associated earth-science data are needed to address key societal and environmental issues such as ground-water quality, landslides and other potential geologic hazards, and land-use decisions. Areas of primary emphasis in 2001 included southern California, the San Francisco Bay region, the Pacific Northwest, and the Las Vegas urban corridor. The team has its headquarters in Menlo Park, California, and maintains smaller field offices at several other locations in the western United States. The results of research conducted by the WESPT are released to the public as a variety of databases, maps, text reports, and abstracts, both through the internal publication system of the USGS and in diverse external publications such as scientific journals and books. This report lists publications of the WESPT released in 2002 as well as additional 1998 and 2001 publications that were not included in the previous list (USGS Open-File Report 00-215, USGS Open-File Report 01-198, and USGS Open-File Report 02-269). Most of the publications listed were authored or coauthored by WESPT staff. The list also includes some publications authored by non-USGS cooperators with the WESPT, as well as some authored by USGS staff outside the WESPT in cooperation with WESPT projects. Several of the publications listed are available on the World Wide Web; for these, URL addresses are provided. Many of these web publications are USGS open-file reports that contain large digital databases of geologic map and related information. Information on ordering USGS publications can be found on the World Wide Web or by calling 1-888-ASK-USGS. The U.S. Geological Survey’s web server for geologic information in the western United States is located at http

  11. Improving the work function of the niobium surface of SRF cavities by plasma processing

    NASA Astrophysics Data System (ADS)

    Tyagi, P. V.; Doleans, M.; Hannah, B.; Afanador, R.; McMahan, C.; Stewart, S.; Mammosser, J.; Howell, M.; Saunders, J.; Degraff, B.; Kim, S.-H.

    2016-04-01

    An in situ plasma processing technique using chemically reactive oxygen plasma to remove hydrocarbons from superconducting radio frequency cavity surfaces at room temperature has been developed at the spallation neutron source, at Oak Ridge National Laboratory. To understand better the interaction between the plasma and niobium surface, surface studies on small samples were performed. In this article, we report the results from those surface studies. The results show that plasma processing removes hydrocarbons from top surface and improves the surface work function by 0.5-1.0 eV. Improving the work function of RF surface of cavities can help to improve their operational performance.

  12. Improving the work function of the niobium surface of SRF cavities by plasma processing

    DOE PAGES

    Tyagi, P. V.; Doleans, M.; Hannah, B.; ...

    2016-01-01

    An in situ plasma processing technique using chemically reactive oxygen plasma to remove hydrocarbons from superconducting radio frequency cavity surfaces at room temperature was developed at the spallation neutron source, at Oak Ridge National Laboratory. To understand better the interaction between the plasma and niobium surface, surface studies on small samples were performed. In this article, we report the results from those surface studies. The results show that plasma processing removes hydrocarbons from top surface and improves the surface work function by 0.5₋1.0 eV. Improving the work function of RF surface of cavities can help to improve their operational performance.

  13. Dust levitation as a major resurfacing process on the surface of a saturnian icy satellite, Atlas

    NASA Astrophysics Data System (ADS)

    Hirata, Naoyuki; Miyamoto, Hideaki

    2012-07-01

    A small inner satellite of Saturn, Atlas, has an enigmatic saucer-like shape explained by an accumulation of particles from A-ring of Saturn. However, its unusual smooth surface remains unexplained. Gardening through continuous particle impact events cannot be a unique explanation for the smoothness, because Prometheus does not exhibit a similar surface, though it too would have experienced a similar bombardment. Here, a detailed investigation using close-up images of Atlas reveals the surface to be (1) covered by fine particles (i.e., probably as small as several tens of micrometers); (2) mostly void of impact craters (i.e., only one has been thus far identified); and (3) continuously smooth, even between the equatorial ridge and the undulating polar region. These findings imply that some sort of crater-erasing process has been active on the surface of Atlas. From electro-static analyses, we propose that the upper-most layer of the fine particles can become electro-statically unstable and migrate as a result of dust levitation, which resulted in erasing craters on the surface of Atlas. If true, Atlas would represent the first recognized body where resurfacing is dominated by dust levitation.

  14. Triangle Geometry Processing for Surface Modeling and Cartesian Grid Generation

    NASA Technical Reports Server (NTRS)

    Aftosmis, Michael J. (Inventor); Melton, John E. (Inventor); Berger, Marsha J. (Inventor)

    2002-01-01

    Cartesian mesh generation is accomplished for component based geometries, by intersecting components subject to mesh generation to extract wetted surfaces with a geometry engine using adaptive precision arithmetic in a system which automatically breaks ties with respect to geometric degeneracies. During volume mesh generation, intersected surface triangulations are received to enable mesh generation with cell division of an initially coarse grid. The hexagonal cells are resolved, preserving the ability to directionally divide cells which are locally well aligned.

  15. Triangle geometry processing for surface modeling and cartesian grid generation

    DOEpatents

    Aftosmis, Michael J [San Mateo, CA; Melton, John E [Hollister, CA; Berger, Marsha J [New York, NY

    2002-09-03

    Cartesian mesh generation is accomplished for component based geometries, by intersecting components subject to mesh generation to extract wetted surfaces with a geometry engine using adaptive precision arithmetic in a system which automatically breaks ties with respect to geometric degeneracies. During volume mesh generation, intersected surface triangulations are received to enable mesh generation with cell division of an initially coarse grid. The hexagonal cells are resolved, preserving the ability to directionally divide cells which are locally well aligned.

  16. Surface Wave Processes on the Shelf and Beach

    DTIC Science & Technology

    2016-06-07

    community model under sponsorship of the National Ocean Partnership Program (PI: J. Kirby). REFERENCES Herbers, T. H. C., and M. C. Burton, Nonlinear...backscatter and aerosol generation. While surface wave spectra in the open ocean evolve slowly over distances of O(100-1000 km), wave properties on...IMPACT/APPLICATIONS Results of this project have provided unique new insights in the statistical properties of ocean surface waves in shallow water and a

  17. Scanning tunneling microscopy of electrochemically activated platinum surfaces. A direct ex-situ determination of the electrode nanotopography

    SciTech Connect

    Vazquez, L.; Gomez, J.; Baro, A.M.; Garcia, N.; Marcos, M.L.; Velasco, J.G.; Vara, J.M.; Arvia, A.J.; Presa, J.; Garcia, A.; Aguilar, M.

    1987-03-18

    A direct scanning tunneling microscopy ex-situ determination on the nanometer scale of the topography of electrochemically highly activated platinum electrodes is presented. A correlation between catalytic activity and surface microtopography becomes evident. This result gives support to a structural model for the activated electrode surface. In the model, a volume with a pebble-like structure allows electrocatalytic processes to occur practically free of diffusion relaxation contributions under usual voltammetric conditions.

  18. Improving mechanical properties of polyethylene orthopaedic implants by high frequency cold plasma surface activation

    NASA Astrophysics Data System (ADS)

    Tudoran, Cristian D.; Vlad, Iulia E.; Dadarlat, Dorin N.; Anghel, Sorin D.

    2013-11-01

    Although a tremendous progress has been made in developing new methods and materials for manufacturing orthopaedic implants, the new technology still faces various problems. Polyethylene implants are relatively easy to manufacture and at lower cost compared to metallic or ceramic implants, but they present a fundamental problem: during usage and in time, due to their manufacturing technology, the material suffers from pitting and delamination which leads to crack propagation and finally to sudden fracture. Our studies and tests performed on polyethylene showed that, using cold plasma surface activation during the manufacturing process of the orthopaedic implants made from polyethylene can significantly increase their mechanical properties. The breaking tests revealed an increase of the tensile strength in the laminated polyethylene samples by a factor of 4 after plasma activation. "Aging" tests have been also performed to investigate how the cold plasma treated samples maintain their properties in time, after the surface activation process.

  19. Modelling the Active Hearing Process in Mosquitoes

    NASA Astrophysics Data System (ADS)

    Avitabile, Daniele; Homer, Martin; Jackson, Joe; Robert, Daniel; Champneys, Alan

    2011-11-01

    A simple microscopic mechanistic model is described of the active amplification within the Johnston's organ of the mosquito species Toxorhynchites brevipalpis. The model is based on the description of the antenna as a forced-damped oscillator coupled to a set of active threads (ensembles of scolopidia) that provide an impulsive force when they twitch. This twitching is in turn controlled by channels that are opened and closed if the antennal oscillation reaches a critical amplitude. The model matches both qualitatively and quantitatively with recent experiments. New results are presented using mathematical homogenization techniques to derive a mesoscopic model as a simple oscillator with nonlinear force and damping characteristics. It is shown how the results from this new model closely resemble those from the microscopic model as the number of threads approach physiologically correct values.

  20. Capturing Cognitive Processing Time for Active Authentication

    DTIC Science & Technology

    2014-02-01

    biometrics, extracted from keystroke dynamics , as “something a user is” for active authentication. This scheme performs continual verification in the...fingerprint for continuous authentication. Its effectiveness has been verified through a large-scale dataset. 2.0 INTRODUCTION Keystroke dynamics —the...measure the similarity. A recent survey on biometric authentication using keystroke dynamics classified research papers on the basis of their

  1. 30 CFR 942.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... surface coal mining operations. 942.764 Section 942.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE TENNESSEE § 942.764 Process for designating areas unsuitable for surface coal mining... Mining Operations, shall apply to surface coal mining and reclamation operations. (b) The Secretary...

  2. 30 CFR 942.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... surface coal mining operations. 942.764 Section 942.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE TENNESSEE § 942.764 Process for designating areas unsuitable for surface coal mining... Mining Operations, shall apply to surface coal mining and reclamation operations. (b) The Secretary...

  3. 30 CFR 942.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... surface coal mining operations. 942.764 Section 942.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE TENNESSEE § 942.764 Process for designating areas unsuitable for surface coal mining... Mining Operations, shall apply to surface coal mining and reclamation operations. (b) The Secretary...

  4. 30 CFR 942.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... surface coal mining operations. 942.764 Section 942.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE TENNESSEE § 942.764 Process for designating areas unsuitable for surface coal mining... Mining Operations, shall apply to surface coal mining and reclamation operations. (b) The Secretary...

  5. 30 CFR 942.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... surface coal mining operations. 942.764 Section 942.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE TENNESSEE § 942.764 Process for designating areas unsuitable for surface coal mining... Mining Operations, shall apply to surface coal mining and reclamation operations. (b) The Secretary...

  6. 30 CFR 905.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... surface coal mining operations. 905.764 Section 905.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE CALIFORNIA § 905.764 Process for designating areas unsuitable for surface coal...

  7. 30 CFR 910.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... surface coal mining operations. 910.764 Section 910.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE GEORGIA § 910.764 Process for designating areas unsuitable for surface coal...

  8. 30 CFR 912.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... surface coal mining operations. 912.764 Section 912.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE IDAHO § 912.764 Process for designating areas unsuitable for surface coal...

  9. 30 CFR 903.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... surface coal mining operations. 903.764 Section 903.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE ARIZONA § 903.764 Process for designating areas unsuitable for surface coal...

  10. Electrochemical and spectroscopic characterization of surface sol-gel processes.

    PubMed

    Chen, Xiaohong; Wilson, George S

    2004-09-28

    (3-Mercaptopropyl)trimethoxysilane (MTS) forms a unique film on a platinum substrate by self-assembly and sol-gel cross-linking. The gelating and drying states of the self-assembled MTS sol-gel films were probed by use of electrochemical and spectroscopic methods. The thiol moiety was the only active group within the sol-gel network. Gold nanoparticles were employed to detect the availability of the thiol group and their interaction further indicated the physicochemical states of the sol-gel inner structure. It was found that the thiol groups in the open porous MTS aerogel matrix were accessible to the gold nanoparticles while thiol groups in the compact MTS xerogel network were not accessible to the gold nanoparticles. The characteristics of the sol-gel matrix change with time because of its own irreversible gelating and drying process. The present work provides direct evidence of gold nanoparticle binding with thiol groups within the sol-gel structures and explains the different permeability of "aerogel" and "xerogel" films of MTS on the basis of electrochemical and spectroscopic results. Two endogenous species, hydrogen peroxide and ascorbic acid, were used to test the permeability of the self-assembled sol-gel film in different states. The MTS xerogel film on the platinum electrode was extremely selective against ascorbic acid while maintaining high sensitivity to hydrogen peroxide in contrast to the relatively high permeability of ascorbic acid in the MTS aerogel film. This study showed the potential of the MTS sol-gel film as a nanoporous material in biosensor development.

  11. An Extended Polyanion Activation Surface in Insulin Degrading Enzyme

    PubMed Central

    Song, Eun Suk; Ozbil, Mehmet; Zhang, Tingting; Sheetz, Michael; Lee, David; Tran, Danny; Li, Sheng; Prabhakar, Rajeev; Hersh, Louis B.; Rodgers, David W.

    2015-01-01

    Insulin degrading enzyme (IDE) is believed to be the major enzyme that metabolizes insulin and has been implicated in the degradation of a number of other bioactive peptides, including amyloid beta peptide (Aβ), glucagon, amylin, and atrial natriuretic peptide. IDE is activated toward some substrates by both peptides and polyanions/anions, possibly representing an important control mechanism and a potential therapeutic target. A binding site for the polyanion ATP has previously been defined crystallographically, but mutagenesis studies suggest that other polyanion binding modes likely exist on the same extended surface that forms one wall of the substrate-binding chamber. Here we use a computational approach to define three potential ATP binding sites and mutagenesis and kinetic studies to confirm the relevance of these sites. Mutations were made at four positively charged residues (Arg 429, Arg 431, Arg 847, Lys 898) within the polyanion-binding region, converting them to polar or hydrophobic residues. We find that mutations in all three ATP binding sites strongly decrease the degree of activation by ATP and can lower basal activity and cooperativity. Computational analysis suggests conformational changes that result from polyanion binding as well as from mutating residues involved in polyanion binding. These findings indicate the presence of multiple polyanion binding modes and suggest the anion-binding surface plays an important conformational role in controlling IDE activity. PMID:26186535

  12. Uav Data Processing for Rapid Mapping Activities

    NASA Astrophysics Data System (ADS)

    Tampubolon, W.; Reinhardt, W.

    2015-08-01

    During disaster and emergency situations, geospatial data plays an important role to serve as a framework for decision support system. As one component of basic geospatial data, large scale topographical maps are mandatory in order to enable geospatial analysis within quite a number of societal challenges. The increasing role of geo-information in disaster management nowadays consequently needs to include geospatial aspects on its analysis. Therefore different geospatial datasets can be combined in order to produce reliable geospatial analysis especially in the context of disaster preparedness and emergency response. A very well-known issue in this context is the fast delivery of geospatial relevant data which is expressed by the term "Rapid Mapping". Unmanned Aerial Vehicle (UAV) is the rising geospatial data platform nowadays that can be attractive for modelling and monitoring the disaster area with a low cost and timely acquisition in such critical period of time. Disaster-related object extraction is of special interest for many applications. In this paper, UAV-borne data has been used for supporting rapid mapping activities in combination with high resolution airborne Interferometric Synthetic Aperture Radar (IFSAR) data. A real disaster instance from 2013 in conjunction with Mount Sinabung eruption, Northern Sumatra, Indonesia, is used as the benchmark test for the rapid mapping activities presented in this paper. On this context, the reliable IFSAR dataset from airborne data acquisition in 2011 has been used as a comparable dataset for accuracy investigation and assessment purpose in 3 D reconstructions. After all, this paper presents a proper geo-referencing and feature extraction method of UAV data to support rapid mapping activities.

  13. Synthesis, surface-active properties, and antimicrobial activities of new double-chain gemini surfactants.

    PubMed

    Murguía, Marcelo C; Vaillard, Victoria A; Sánchez, Victoria G; Conza, José Di; Grau, Ricardo J

    2008-01-01

    A novel series of neutral and cationic dimeric surfactants were prepared involving ketalization reaction, Williamson etherification, and regioselective oxirane ring opening with primary and tertiary alkyl amines. The critical micelle concentration (CMC), effectiveness of surface tension reduction (gamma(CMC)), surface excess concentration (Gamma), and area per molecule at the interface (A) were determined and values indicate that the cationic series is characterized by good surface-active and self-aggregation properties. For the first time, we reported the antimicrobial activities against representative bacteria and fungi for dimeric compounds. The antimicrobial activity was found to be dependent on the target microorganism (Gram-positive bacteria > fungi > Gram-negative bacteria), as well as both the neutral or ionic nature (cationic > neutral) and alkyl chain length (di-C(12) > di-C(18) > di-C(8)) of the compounds. The cationic di-C(12) derivative was found to have equipotent activity to that of benzalkonium chloride (BAC) used as standard.

  14. Processing abstract language modulates motor system activity.

    PubMed

    Glenberg, Arthur M; Sato, Marc; Cattaneo, Luigi; Riggio, Lucia; Palumbo, Daniele; Buccino, Giovanni

    2008-06-01

    Embodiment theory proposes that neural systems for perception and action are also engaged during language comprehension. Previous neuroimaging and neurophysiological studies have only been able to demonstrate modulation of action systems during comprehension of concrete language. We provide neurophysiological evidence for modulation of motor system activity during the comprehension of both concrete and abstract language. In Experiment 1, when the described direction of object transfer or information transfer (e.g., away from the reader to another) matched the literal direction of a hand movement used to make a response, speed of responding was faster than when the two directions mismatched (an action-sentence compatibility effect). In Experiment 2, we used single-pulse transcranial magnetic stimulation to study changes in the corticospinal motor pathways to hand muscles while reading the same sentences. Relative to sentences that do not describe transfer, there is greater modulation of activity in the hand muscles when reading sentences describing transfer of both concrete objects and abstract information. These findings are discussed in relation to the human mirror neuron system.

  15. Nanoscale electrochemical patterning reveals the active sites for catechol oxidation at graphite surfaces.

    PubMed

    Patel, Anisha N; McKelvey, Kim; Unwin, Patrick R

    2012-12-19

    Graphite-based electrodes (graphite, graphene, and nanotubes) are used widely in electrochemistry, and there is a long-standing view that graphite step edges are needed to catalyze many reactions, with the basal surface considered to be inert. In the present work, this model was tested directly for the first time using scanning electrochemical cell microscopy reactive patterning and shown to be incorrect. For the electro-oxidation of dopamine as a model process, the reaction rate was measured at high spatial resolution across a surface of highly oriented pyrolytic graphite. Oxidation products left behind in a pattern defined by the scanned electrochemical cell served as surface-site markers, allowing the electrochemical activity to be correlated directly with the graphite structure on the nanoscale. This process produced tens of thousands of electrochemical measurements at different locations across the basal surface, unambiguously revealing it to be highly electrochemically active, with step edges providing no enhanced activity. This new model of graphite electrodes has significant implications for the design of carbon-based biosensors, and the results are additionally important for understanding electrochemical processes on related sp(2)-hybridized materials such as pristine graphene and nanotubes.

  16. Silicon surface-electrode ion traps for quantum information processing

    NASA Astrophysics Data System (ADS)

    Doret, S. Charles; Slusher, Richart

    2010-03-01

    The Georgia Tech Research Institute (GTRI) is designing, building, and testing scalable surface-electrode ion traps for quantum information applications, fabricated using silicon VLSI technology. A wide range of trap architectures have been developed, including a linear trap capable of holding long chains of equally spaced ions, a 90-degree X-junction, and an integrated micromirror with collection efficiency approaching 20%. Fabrication features that can be integrated with the surface electrodes include multilayer interconnects, optics for enhanced light collection, flexible optical access through beveled slots extending through the substrate, and recessed wire bonds for clear laser access across the trap surface. Traps are designed at GTRI using in-house codes that calculate trap fields, compute the full motion of ions confined in the trap, including micromotion, and optimize electrode shapes and transport waveforms using genetic algorithms. We will present designs and initial test results for several of these traps, as well as plans for their use in future experiments.

  17. Dental Surface Texture Characterization Based on Erosive Tooth Wear Processes.

    PubMed

    Hara, A T; Livengood, S V; Lippert, F; Eckert, G J; Ungar, P S

    2016-05-01

    The differential diagnosis of dental wear lesions affects their clinical management. We hypothesized that surface texture parameters can differentiate simulated erosion, abrasion, and erosion-abrasion lesions on human enamel and dentin. This in vitro study comprised 2 parts (both factorial 4 × 2), with 4 lesion types (erosion, abrasion, erosion-abrasion, and sound [no lesion; control]) and 2 substrates (enamel and dentin). Flattened/polished dental specimens were used in part 1, whereas natural dental surfaces were used in part 2. Testing surfaces were evaluated in blind conditions, using average surface roughness (Sa) and the following scale-sensitive fractal analysis parameters: area-scale fractal complexity (Asfc), exact proportion length-scale anisotropy of relief (eplsar), scale of maximum complexity (Smc), and textural fill volume (Tfv). Two-way analyses of variance, followed by Fisher's protected least significant difference tests (α = 0.05), were used to evaluate the effects of lesion and substrate. Classification trees were constructed to verify the strength of potential associations of the tested parameters. In part 1,Asfc, Sa, and Tfv were able to differentiate erosion and erosion-abrasion lesions from the sound (no lesion) control in both substrates; only Asfc differentiated erosion and erosion-abrasion enamel lesions (allP< 0.05). The best association of parameters correctly classified up to 84% and 94% of the lesions on enamel and dentin, respectively. In part 2, only Asfc differentiated erosion and erosion-abrasion lesions from the sound (no lesion) control in both substrates, whereas eplsar was able to differentiate erosion from erosion-abrasion (allP< 0.05). The association of parameters correctly classified up to 81% and 91% of the lesions in enamel and dentin, respectively.Asfc, Sa, and Tfv were able to differentiate erosion and erosion-abrasion lesions, despite their complicated surface textures. The association of parameters improved the

  18. Nitrate reducing activity pervades surface waters during upwelling

    NASA Astrophysics Data System (ADS)

    Fernandes, Sheryl Oliveira; Halarnekar, Reena; Malik, Ashish; Vijayan, Vijitha; Varik, Sandesh; Kumari, Ritu; V. K., Jineesh; Gauns, Manguesh U.; Nair, Shanta; LokaBharathi, P. A.

    2014-09-01

    Nitrate reducing activity (NRA) is known to be mediated by microaerophilic to anaerobic bacteria and generally occurs in the sub-surface waters. However, we hypothesize that NRA could become prominent in the surface waters during upwelling. Hence, we examined nitrification and nitrate reduction along with hydrographic and environmental parameters off Trivandrum and Kochi, south-west-India in June 2010. Shoaling isolines of temperature, density, and nutrients revealed the onset of upwelling off Trivandrum. Shoaling of these signatures was absent in the northern transect off Kochi. The degree of nutrient consumption (DNC) was low emphasizing the presence of newly upwelled water off Trivandrum. A significant increase in NRA (df = 1, p < 0.05) was observed off Trivandrum than at Kochi. Moreover, as hypothesized, NRA at Trivandrum was pronounced at the surface with a maximum rate of 0.85 (± 0.02) μmol L1 h- 1 nearshore which was ~ 29 × higher than that at Kochi. Further, an inverse relationship between NRA and NO3- concentration (n = 34, r = - 0.415, p < 0.01) suggested transformation of the upwelled nutrient. Nitrification/NRA was ~ 10 × lower at 0.28 off Trivandrum indicating a discernible shift towards reduction. Such contribution from bacterial activity could be a response towards restoration of homeostasis.

  19. Functional Imaging of Chemically Active Surfaces with Optical Reporter Microbeads

    PubMed Central

    Ahuja, Punkaj; Nair, Sumitha; Narayan, Sreenath; Gratzl, Miklós

    2015-01-01

    We have developed a novel approach to allow for continuous imaging of concentration fields that evolve at surfaces due to release, uptake, and mass transport of molecules, without significant interference of the concentration fields by the chemical imaging itself. The technique utilizes optical “reporter” microbeads immobilized in a thin layer of transparent and inert hydrogel on top of the surface. The hydrogel has minimal density and therefore diffusion in and across it is like in water. Imaging the immobilized microbeads over time provides quantitative concentration measurements at each location where an optical reporter resides. Using image analysis in post-processing these spatially discrete measurements can be transformed into contiguous maps of the dynamic concentration field across the entire surface. If the microbeads are small enough relative to the dimensions of the region of interest and sparsely applied then chemical imaging will not noticeably affect the evolution of concentration fields. In this work colorimetric optode microbeads a few micrometers in diameter were used to image surface concentration distributions on the millimeter scale. PMID:26332766

  20. Laboratory studies of aeolian sediment transport processes on planetary surfaces

    NASA Astrophysics Data System (ADS)

    Rasmussen, Keld R.; Valance, Alexandre; Merrison, Jonathan

    2015-09-01

    , but not all, older or recent wind tunnel observations. Similarly some measurements performed with uniform sand samples having grain diameters of the order of 0.25-0.40 mm indicate that ripple spacing depends on friction velocity in a similar way as particle jump length. The observations are thus in agreement with a recent ripple model that link the typical jump length to ripple spacing. A possible explanation for contradictory observations in some experiments may be that long observation sequences are required in order to assure that equilibrium exists between ripple geometry and wind flow. Quantitative understanding of saltation characteristics on Mars still lacks important elements. Based upon image analysis and numerical predictions, aeolian ripples have been thought to consist of relatively large grains (diameter > 0.6 mm) and that saltation occurs at high wind speeds (> 26 m/s) involving trajectories that are significantly longer than those on Earth (by a factor of 10-100). However, this is not supported by recent observations from the surface of Mars, which shows that active ripples in their geometry and composition have characteristics compatible with those of terrestrial ripples (Sullivan et al., 2008). Also the highest average wind speeds on Mars have been measured to be < 20 m/s, with even turbulent gusts not exceeding 25 m/s. Electrification is seen as a dominant factor in the transport dynamics of dust on Mars, affecting the structure, adhesive properties and detachment/entrainment mechanisms specifically through the formation of aggregates (Merrison et al., 2012). Conversely for terrestrial conditions electric fields typically observed are not intense enough to significantly affect sand transport rates while little is known in the case of extra-terrestrial environments.

  1. Patched bimetallic surfaces are active catalysts for ammonia decomposition

    DOE PAGES

    Guo, Wei; Vlachos, Dionisios G.

    2015-10-07

    In this study, ammonia decomposition is often used as an archetypical reaction for predicting new catalytic materials and understanding the very reason of why some reactions are sensitive on material’s structure. Core–shell or surface-segregated bimetallic nanoparticles expose outstanding activity for many heterogeneously catalysed reactions but the reasons remain elusive owing to the difficulties in experimentally characterizing active sites. Here by performing multiscale simulations in ammonia decomposition on various nickel loadings on platinum (111), we show that the very high activity of core–shell structures requires patches of the guest metal to create and sustain dual active sites: nickel terraces catalyse N-Hmore » bond breaking and nickel edge sites drive atomic nitrogen association. The structure sensitivity on these active catalysts depends profoundly on reaction conditions due to kinetically competing relevant elementary reaction steps. We expose a remarkable difference in active sites between transient and steady-state studies and provide insights into optimal material design.« less

  2. Observations on Multi-Slug Activity - Implications for Volcanic Processes

    NASA Astrophysics Data System (ADS)

    Pering, T. D.; McGonigle, A. J. S.; James, M. R.; Lane, S. J.; Capponi, A.; Tamburello, G.; Aiuppa, A.

    2014-12-01

    The study of single gas slugs in volcanic conduits has received a large amount of focus within the literature. However, the more complex behaviour associated with the rise and burst of multiple slugs has yet to be considered in detail in a volcanic context. Here we combine observations and analyses of such activity using a three-pronged approach consisting of existing gas mass data collected during rapid slug driven activity at Mt. Etna, scaled laboratory analogue experiments, and computer simulations using the Ansys Fluent® fluid dynamics software. Particular focus was applied to the process of coalescence and wake capture during slug expansion and rise. The results indicate a variety of potential features and relationships, including: promotion of coalescence at distances further than predicted wake lengths, approximate maximum gas volume fraction and minimum magma viscosity values for the occurrence of stable multi-slug activity, and in the laboratory regimes a series of linear trends are associated with overall gas volume fraction and burst volume. A previously observed phenomenon at Mt. Etna, whereby larger slug bursting events are subject to a longer repose period prior to the following event, than smaller events, is also evident in the lab setting. By combining all acquired and modelled data, we derive an approximate relation, using existing formulae for slug base rise speed (Viana et al. 2003) and wake length (Campos and Guedes de Carvalho, 1988), to describe a minimum repose period which is likely to follow the burst of a slug at the surface. The outlined work has significant fluid dynamic implications for possible magma and conduit properties which can allow multi-slug activity at volcanic targets.

  3. Vigorous Convection Underlies Pluto’s Surface Activity

    NASA Astrophysics Data System (ADS)

    Trowbridge, Alexander J.; Melosh, Henry Jay; Freed, Andy M.

    2015-11-01

    Against many expectations, New Horizons’ images of the surface of Pluto and Charon show seemingly young surfaces. On Pluto, images of an equatorial region south of the Tombaugh Regio reveal a mountain range with peaks jutting as high as 3,500 meters. The low concentration of craters for these mountains suggests an age of 100 million years, indicating that Pluto is geologically active. Other evidence for geologic activity includes a fault cross-cutting ridges, smooth lightly cratered plains with flow fronts, and a pair of apparent stratovolcanoes. Charon similarly possesses very few craters and a spectacular system of troughs. Both observations suggest the possible presence of active cryogeysers and cryovolcanoes. The underlying cause of modern tectonic and volcanic activity on any object is likely a vigorous mantle convection regime. We are thus led to consider what determines planetary vigor. While Pluto and Charon seem to be quite active, Ceres and the much larger Callisto seem to lack modern endogenic activity, even though all of these bodies are likely to possess water ice mantles.We coupled a parameterized convection model with a temperature dependent rheology for pure water ice, deducing a barely critical Rayleigh number of ~1600 for Pluto’s mantle and <1000 for Charon, suggesting that a water ice mantle alone may be insufficient to support vigorous convection in these bodies. However, in the outer solar system, other volatiles may have condensed. Ammonium hydrate has been reported on the surface of Charon. At temperatures above the eutectic (176 K), Durham et al. (1993) showed that NH3 lowers the viscosity of water ice by 4 orders of magnitude. Our model indicates that, with NH3, the mean temperature of the mantle of Pluto is at the eutectic and its Ra ~ 10^4. The presence of NH3 dramatically increases the vigor of convection for the two bodies and suggests that ammonia-water slurries are the basis for Pluto’s volcanism. We propose that the presence or

  4. Superhydrophobic metallic surfaces functionalized via femtosecond laser surface processing for long term air film retention when submerged in liquid

    NASA Astrophysics Data System (ADS)

    Zuhlke, Craig A.; Anderson, Troy P.; Li, Pengbo; Lucis, Michael J.; Roth, Nick; Shield, Jeffrey E.; Terry, Benjamin; Alexander, Dennis R.

    2015-03-01

    Femtosecond laser surface processing (FLSP) is a powerful technique used to create self-organized microstructures with nanoscale features on metallic surfaces. By combining FLSP surface texturing with surface chemistry changes, either induced by the femtosecond laser during processing or introduced through post processing techniques, the wetting properties of metals can be altered. In this work, FLSP is demonstrated as a technique to create superhydrophobic surfaces on grade 2 titanium and 304 stainless steel that can retain an air film (plastron) between the surface and a surrounding liquid when completely submerged. It is shown that the plastron lifetime when submerged in distilled water or synthetic stomach acid is critically dependent on the specific degree of surface micro- and nano-roughness, which can be tuned by controlling various FLSP parameters. The longest plastron lifetime was on a 304 stainless steel sample that was submerged in distilled water and maintained a plastron for 41 days, the length of time of the study, with no signs of degradation. Also demonstrated for the first time is the precise control of pulse fluence and pulse count to produce three unique classes of surface micron/nano-structuring on titanium.

  5. Redox activity of surface oxygen anions in oxygen-deficient perovskite oxides during electrochemical reactions.

    PubMed

    Mueller, David N; Machala, Michael L; Bluhm, Hendrik; Chueh, William C

    2015-01-19

    Surface redox-active centres in transition-metal oxides play a key role in determining the efficacy of electrocatalysts. The extreme sensitivity of surface redox states to temperatures, to gas pressures and to electrochemical reaction conditions renders them difficult to investigate by conventional surface-science techniques. Here we report the direct observation of surface redox processes by surface-sensitive, operando X-ray absorption spectroscopy using thin-film iron and cobalt perovskite oxides as model electrodes for elevated-temperature oxygen incorporation and evolution reactions. In contrast to the conventional view that the transition metal cations are the dominant redox-active centres, we find that the oxygen anions near the surface are a significant redox partner to molecular oxygen due to the strong hybridization between oxygen 2p and transition metal 3d electronic states. We propose that a narrow electronic state of significant oxygen 2p character near the Fermi level exchanges electrons with the oxygen adsorbates. This result highlights the importance of surface anion-redox chemistry in oxygen-deficient transition-metal oxides.

  6. Earthquake rupture process recreated from a natural fault surface

    USGS Publications Warehouse

    Parsons, Thomas E.; Minasian, Diane L.

    2015-01-01

    What exactly happens on the rupture surface as an earthquake nucleates, spreads, and stops? We cannot observe this directly, and models depend on assumptions about physical conditions and geometry at depth. We thus measure a natural fault surface and use its 3D coordinates to construct a replica at 0.1 m resolution to obviate geometry uncertainty. We can recreate stick-slip behavior on the resulting finite element model that depends solely on observed fault geometry. We clamp the fault together and apply steady state tectonic stress until seismic slip initiates and terminates. Our recreated M~1 earthquake initiates at contact points where there are steep surface gradients because infinitesimal lateral displacements reduce clamping stress most efficiently there. Unclamping enables accelerating slip to spread across the surface, but the fault soon jams up because its uneven, anisotropic shape begins to juxtapose new high-relief sticking points. These contacts would ultimately need to be sheared off or strongly deformed before another similar earthquake could occur. Our model shows that an important role is played by fault-wall geometry, though we do not include effects of varying fluid pressure or exotic rheologies on the fault surfaces. We extrapolate our results to large fault systems using observed self-similarity properties, and suggest that larger ruptures might begin and end in a similar way, though the scale of geometrical variation in fault shape that can arrest a rupture necessarily scales with magnitude. In other words, fault segmentation may be a magnitude dependent phenomenon and could vary with each subsequent rupture.

  7. Resonant charge transfer process in ion-metal surface collisions: effect of the presence of vacancies on the surface

    NASA Astrophysics Data System (ADS)

    Silva, J. A. M. C.; Wolfgang, J.; Borisov, A. G.; Gauyacq, J. P.; Nordlander, P.; Teillet-Billy, D.

    In this paper an investigation of how the presence of a vacancy on a metal surface influences the energy shift and broadening of negative ion states near the surface is presented. Results for H - and F - ions in the vicinity of a surface vacancy defect on an Al(1 1 1) surface are included. The vacancy-induced electron potential is calculated using a density functional method and the Coupled Angular Mode (CAM) method is used to determine the shift and broadening of H - and F - levels. The results show that the vacancy induces a repulsive potential, shifting the negative ion levels up, while narrowing the width. These two effects have opposite influences on the resonant charge transfer process. Their approximate cancellation makes the RCT process in these systems relatively insensitive to vacancies in the surface layer.

  8. U.S. Geological Survey quality-assurance plan for surface-water activities in Kansas, 2015

    USGS Publications Warehouse

    Painter, Collin C.; Loving, Brian L.

    2015-01-01

    This Surface Water Quality-Assurance Plan documents the standards, policies, and procedures used by the Kansas Water Science Center (KSWSC) of the U.S. Geological Survey (USGS) for activities related to the collection, processing, storage, analysis, and publication of surface-water data.

  9. Electrostatic application of antimicrobial sprays to sanitize food handling and processing surfaces for enhanced food safety

    NASA Astrophysics Data System (ADS)

    Lyons, Shawn M.; Harrison, Mark A.; Law, S. Edward

    2011-06-01

    Human illnesses and deaths caused by foodborne pathogens (e.g., Salmonella enterica, Listeria monocytogenes, Escherichia coli O157:H7, etc.) are of increasing concern globally in maintaining safe food supplies. At various stages of the food production, processing and supply chain antimicrobial agents are required to sanitize contact surfaces. Additionally, during outbreaks of contagious pathogenic microorganisms (e.g., H1N1 influenza), public health requires timely decontamination of extensive surfaces within public schools, mass transit systems, etc. Prior publications verify effectiveness of air-assisted, induction-charged (AAIC) electrostatic spraying of various chemical and biological agents to protect on-farm production of food crops...typically doubling droplet deposition efficiency with concomitant increases in biological control efficacy. Within a biosafety facility this present work evaluated the AAIC electrostatic-spraying process for application of antimicrobial liquids onto various pathogen-inoculated food processing and handling surfaces as a food safety intervention strategy. Fluoroanalysis of AAIC electrostatic sprays (-7.2 mC/kg charge-to-mass ratio) showed significantly greater (p<0.05) mass of tracer active ingredient (A.I.) deposited onto target surfaces at various orientations as compared both to a similar uncharged spray nozzle (0 mC/kg) and to a conventional hydraulic-atomizing nozzle. Per unit mass of A.I. dispensed toward targets, for example, A.I. mass deposited by AAIC electrostatic sprays onto difficult to coat backsides was 6.1-times greater than for similar uncharged sprays and 29.0-times greater than for conventional hydraulic-nozzle sprays. Even at the 56% reduction in peracetic acid sanitizer A.I. dispensed by AAIC electrostatic spray applications, they achieved equal or greater CFU population reductions of Salmonella on most target orientations and materials as compared to uncharged sprays and conventional full-rate hydraulic

  10. 43 CFR 3420.3 - Activity planning: The leasing process.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Activity planning: The leasing process... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) COMPETITIVE LEASING Competitive Leasing § 3420.3 Activity planning: The leasing process....

  11. 43 CFR 3420.3 - Activity planning: The leasing process.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Activity planning: The leasing process... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) COMPETITIVE LEASING Competitive Leasing § 3420.3 Activity planning: The leasing process....

  12. 43 CFR 3420.3 - Activity planning: The leasing process.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Activity planning: The leasing process... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) COMPETITIVE LEASING Competitive Leasing § 3420.3 Activity planning: The leasing process....

  13. 12 CFR 211.604 - Data processing activities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 2 2013-01-01 2013-01-01 false Data processing activities. 211.604 Section 211... processing activities under Regulation K (12 CFR part 211). This question has arisen as a result of the fact... authority in Regulation K was somewhat broader than that permissible in the United States under Regulation...

  14. 12 CFR 211.604 - Data processing activities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 2 2011-01-01 2011-01-01 false Data processing activities. 211.604 Section 211... processing activities under Regulation K (12 CFR part 211). This question has arisen as a result of the fact... authority in Regulation K was somewhat broader than that permissible in the United States under Regulation...

  15. 12 CFR 211.604 - Data processing activities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 2 2014-01-01 2014-01-01 false Data processing activities. 211.604 Section 211... processing activities under Regulation K (12 CFR part 211). This question has arisen as a result of the fact... authority in Regulation K was somewhat broader than that permissible in the United States under Regulation...

  16. 12 CFR 211.604 - Data processing activities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 2 2012-01-01 2012-01-01 false Data processing activities. 211.604 Section 211... processing activities under Regulation K (12 CFR part 211). This question has arisen as a result of the fact... authority in Regulation K was somewhat broader than that permissible in the United States under Regulation...

  17. 12 CFR 211.604 - Data processing activities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 2 2010-01-01 2010-01-01 false Data processing activities. 211.604 Section 211... processing activities under Regulation K (12 CFR part 211). This question has arisen as a result of the fact... authority in Regulation K was somewhat broader than that permissible in the United States under Regulation...

  18. 43 CFR 3420.3 - Activity planning: The leasing process.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Activity planning: The leasing process... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) COMPETITIVE LEASING Competitive Leasing § 3420.3 Activity planning: The leasing process....

  19. An active thermal control surfaces experiment. [spacecraft temperature determination

    NASA Technical Reports Server (NTRS)

    Wilkes, D. R.; Brown, M. J.

    1979-01-01

    An active flight experiment is described that has the objectives to determine the effects of the low earth natural environment and the Shuttle induced environment on selected thermal control and optical surfaces. The optical and thermal properties of test samples will be measured in-situ using an integrating sphere reflectrometer and using calorimetric methods. This experiment has been selected for the Long Duration Exposure Facility (LDEF) flight which will be carried to orbit by the NASA Space Shuttle. The LDEF will remain in orbit to be picked up by a later Shuttle mission and returned for postflight evaluation.

  20. Perspective of surface active agents in baking industry: an overview.

    PubMed

    Ahmad, Asif; Arshad, Nazish; Ahmed, Zaheer; Bhatti, Muhammad Shahbaz; Zahoor, Tahir; Anjum, Nomana; Ahmad, Hajra; Afreen, Asma

    2014-01-01

    Different researchers have previously used surfactants for improving bread qualities and revealed that these compounds result in improving the quality of dough and bread by influencing dough strength, tolerance, uniform crumb cell size, and improve slicing characteristics and gas retention. The objective of this review is to highlight the areas where surfactants are most widely used particularly in the bread industries, their role and mechanism of interaction and their contribution to the quality characteristics of the dough and bread. This review reveals some aspects of surface-active agents regarding its role physiochemical properties of dough that in turn affect the bread characteristics by improving its sensory quality and storage stability.

  1. Molluscicidal properties and selective toxicity of surface-active agents

    PubMed Central

    Visser, S. A.

    1965-01-01

    Of over 100 commercially produced surface-active agents tested against the bilharziasis vector snail Biomphalaria sudanica, 13 were found to possess considerable and highly selective molluscicidal properties at concentrations of less than 1 ppm for exposures of 48 hours. Against crustacea, fish, water plants, mosquito larvae, mice, and the eggs of B. sudanica, the toxicities of the 13 surfactants were slight. The chemicals did not appear to be absorbed by organic matter to any appreciable extent. It is thought that the toxicity to B. sudanica is of both a chemical and a physical nature. PMID:5294185

  2. Free energy surfaces from nonequilibrium processes without work measurement.

    PubMed

    Adib, Artur B

    2006-04-14

    Recent developments in statistical mechanics have allowed the estimation of equilibrium free energies from the statistics of work measurements during processes that drive the system out of equilibrium. Here a different class of processes is considered, wherein the system is prepared and released from a nonequilibrium state, and no external work is involved during its observation. For such "clamp-and-release" processes, a simple strategy for the estimation of equilibrium free energies is offered. The method is illustrated with numerical simulations and analyzed in the context of tethered single-molecule experiments.

  3. Physicochemical and porosity characteristics of thermally regenerated activated carbon polluted with biological activated carbon process.

    PubMed

    Dong, Lihua; Liu, Wenjun; Jiang, Renfu; Wang, Zhansheng

    2014-11-01

    The characteristics of thermally regenerated activated carbon (AC) polluted with biological activated carbon (BAC) process were investigated. The results showed that the true micropore and sub-micropore volume, pH value, bulk density, and hardness of regenerated AC decreased compared to the virgin AC, but the total pore volume increased. XPS analysis displayed that the ash contents of Al, Si, and Ca in the regenerated AC respectively increased by 3.83%, 2.62% and 1.8%. FTIR spectrum showed that the surface functional groups of virgin and regenerated AC did not change significantly. Pore size distributions indicated that the AC regeneration process resulted in the decrease of micropore and macropore (D>10 μm) volume and the increase of mesopore and macropore (0.1 μmprocess.

  4. Atomic-level imaging, processing and characterization of semiconductor surfaces

    DOEpatents

    Kazmerski, L.L.

    1995-08-22

    A method for selecting and removing single specific atoms from a solid material surface uses photon biasing to break down bonds that hold the selected atom in the lattice and to reduce barrier effects that hold the atom from transferring to a probe. The photon bias is preferably light or other electromagnetic radiation with a wavelength and frequency that approximately matches the wave function of the target atom species to be removed to induce high energy, selective thermionic-like vibration. An electric field potential is then applied between the probe and the surface of the solid material to pull the atom out of the lattice and to transfer the atom to the probe. Different extrinsic atoms can be installed in the lattice sites that are vacated by the removed atoms by using a photon bias that resonates the extrinsic atom species, reversing polarity of the electric field, and blowing gas comprising the extrinsic atoms through a hollow catheter probe. 8 figs.

  5. Atomic-level imaging, processing and characterization of semiconductor surfaces

    DOEpatents

    Kazmerski, Lawrence L.

    1995-01-01

    A method for selecting and removing single specific atoms from a solid material surface uses photon biasing to break down bonds that hold the selected atom in the lattice and to reduce barrier effects that hold the atom from transferring to a probe. The photon bias is preferably light or other electromagnetic radiation with a wavelength and frequency that approximately matches the wave function of the target atom species to be removed to induce high energy, selective thermionic-like vibration. An electric field potential is then applied between the probe and the surface of the solid material to pull the atom out of the lattice and to transfer the atom to the probe. Different extrinsic atoms can be installed in the lattice sites that are vacated by the removed atoms by using a photon bias that resonates the extrinsic atom species, reversing polarity of the electric field, and blowing gas comprising the extrinsic atoms through a hollow catheter probe.

  6. Si(100) surfaces in a hydrogen-based process ambient

    NASA Astrophysics Data System (ADS)

    Döscher, Henning; Dobrich, Anja; Brückner, Sebastian; Kleinschmidt, Peter; Hannappel, Thomas

    2010-10-01

    We studied the atomic surface properties of Si(100) during preparation in a (metal-organic) vapor phase epitaxy (VPE) reactor and the impact of the hydrogen ambient. Absorption lines in Fourier-transform infrared spectra were identified as stretch modes of coupled Si-H monohydrides, in agreement with Si-dimers observed by scanning tunneling microscopy. The polarization dependence of the antisymmetric stretch mode distinguished different dimer orientations and verified a clear preference for one of the (2×1)/(1×2) surface reconstruction domains. Tip-induced H-desorption proved the complete saturation of dangling bonds after VPE-preparation. In situ reflectance anisotropy spectroscopy showed the absence of Si-H bonds at elevated annealing temperature.

  7. Physical Processes Leading to Surface Inhomogeneities: The Case of Rotation

    NASA Astrophysics Data System (ADS)

    Rieutord, Michel

    2016-04-01

    In this lecture I discuss the bulk surface heterogeneity of rotating stars, namely gravity darkening. I especially detail the derivation of the ω-model of Espinosa Lara and Rieutord (Astron Astrophys 533:A43, 2011), which gives the gravity darkening in early-type stars. I also discuss the problem of deriving gravity darkening darkening in stars owning a convective envelope and in those that are members of a binary system.

  8. Atmospheric mercury accumulation and washoff processes on impervious urban surfaces

    USGS Publications Warehouse

    Eckley, C.S.; Branfireun, B.; Diamond, M.; Van Metre, P.C.; Heitmuller, F.

    2008-01-01

    The deposition and transport of mercury (Hg) has been studied extensively in rural environments but is less understood in urbanized catchments, where elevated atmospheric Hg concentrations and impervious surfaces may efficiently deliver Hg to waterways in stormwater runoff. We determined the rate at which atmospheric Hg accumulates on windows, identified the importance of washoff in removing accumulated Hg, and measured atmospheric Hg concentrations to help understand the relationship between deposition and surface accumulation. The main study location was Toronto, Ontario. Similar samples were also collected from Austin, Texas for comparison of Hg accumulation between cities. Windows provided a good sampling surface because they are ubiquitous in urban environments and are easy to clean/blank allowing the assessment of contemporary Hg accumulation. Hg Accumulation rates were spatially variable ranging from 0.82 to 2.7 ng m-2 d-1 in Toronto and showed similar variability in Austin. The highest accumulation rate in Toronto was at the city center and was 5?? higher than the rural comparison site (0.58 ng m-2 d-1). The atmospheric total gaseous mercury (TGM) concentrations were less than 2?? higher between the rural and urban locations (1.7 ?? 0.3 and 2.7 ?? 1.1 ng m-3, respectively). The atmospheric particulate bound fraction (HgP), however, was more than 3?? higher between the rural and urban sites, which may have contributed to the higher urban Hg accumulation rates. Windows exposed to precipitation had 73 ?? 9% lower accumulation rates than windows sheltered from precipitation. Runoff collected from simulated rain events confirmed that most Hg accumulated on windows was easily removed and that most of the Hg in washoff was HgP. Our results indicate that the Hg flux from urban catchments will respond rapidly to changes in atmospheric concentrations due to the mobilization of the majority of the surface accumulated Hg during precipitation events. ?? 2008 Elsevier

  9. N-nitrosamines formation from secondary amines by nitrogen fixation on the surface of activated carbon.

    PubMed

    Padhye, Lokesh P; Hertzberg, Benjamin; Yushin, Gleb; Huang, Ching-Hua

    2011-10-01

    Our previous study demonstrated that many commercial activated carbon (AC) particles may catalyze transformation of secondary amines to yield trace levels of N-nitrosamines under ambient aerobic conditions. Because of the widespread usage of AC materials in numerous analytical and environmental applications, it is imperative to understand the reaction mechanism responsible for formation of nitrosamine on the surface of ACs to minimize their occurrence in water treatment systems and during analytical methods employing ACs. The study results show that the AC-catalyzed nitrosamine formation requires both atmospheric oxygen and nitrogen. AC's surface reactive sites react with molecular oxygen to form reactive oxygen species (ROS), which facilitate fixation of molecular nitrogen on the carbon surfaces to generate reactive nitrogen species (RNS) likely nitrous oxide and hydroxylamine that can react with adsorbed amines to form nitrosamines. AC's properties play a crucial role as more nitrosamine formation is associated with carbon surfaces with higher surface area, more surface defects, reduced surface properties, higher O(2) uptake capacity, and higher carbonyl group content. This study is a first of its kind on the nitrosamine formation mechanism involving nitrogen fixation on AC surfaces, and the information will be useful for minimization of nitrosamines in AC-based processes.

  10. Measurement of action spectra of light-activated processes

    NASA Astrophysics Data System (ADS)

    Ross, Justin; Zvyagin, Andrei V.; Heckenberg, Norman R.; Upcroft, Jacqui; Upcroft, Peter; Rubinsztein-Dunlop, Halina H.

    2006-01-01

    We report on a new experimental technique suitable for measurement of light-activated processes, such as fluorophore transport. The usefulness of this technique is derived from its capacity to decouple the imaging and activation processes, allowing fluorescent imaging of fluorophore transport at a convenient activation wavelength. We demonstrate the efficiency of this new technique in determination of the action spectrum of the light mediated transport of rhodamine 123 into the parasitic protozoan Giardia duodenalis.

  11. Speech Perception as a Cognitive Process: The Interactive Activation Model.

    DTIC Science & Technology

    1983-04-01

    one another in COHORT, the nodes for sell, your, light, and cellulite , wil all bc in active competition with one another. The system will have no way...7 AD-AI28 787 SPEECH PERCEPTION AS A COGNITIVE PROCESS: THE INTERACTIVE ACTIVATION MODE..(U) CALIFORNIA UNIV SAN D IEGO LA dOLLA INST FOR COGNITIVE...TYPE OF REPORT & PERIOD COVERED Speech Perception as a Cognitive Process: Technical Report The Interactive Activation Model S. PERFORMING ORG. REPORT

  12. GeoComplexity and scale: surface processes and remote sensing of geosystems. GeoComplexity and scale: surface processes and remote sensing of geosystems

    NASA Astrophysics Data System (ADS)

    Muller, Jan-Peter

    2015-04-01

    Understanding the role of scaling in different planetary surface processes within our Solar System is one of the fundamental goals of planetary and solid earth scientific research. There has been a revolution in planetary surface observations over the past decade for the Earth, Mars and the Moon, especially in 3D imaging of surface shape (from the planetary scale down to resolutions of 75cm). I will examine three areas that I have been active in over the last 25 years giving examples of newly processed global datasets ripe for scaling analysis: topography, BRDF/albedo and imaging. For understanding scaling in terrestrial land surface topography we now have global 30m digital elevation models (DEMs) from different types of sensors (InSAR and stereo-optical) along with laser altimeter data to provide global reference models (to better than 1m in cross-over areas) and airborne laser altimeter data over small areas at resolutions better than 1m and height accuracies better than 10-15cm. We also have an increasing number of sub-surface observations from long wavelength SAR in arid regions, which will allow us to look at the true surface rather than the one buried by sand. We also still have a major limitation of these DEMs in that they represent an unknown observable surface with C-band InSAR DEMs representing being somewhere near the top of the canopy and X-band InSAR and stereo near the top of the canopy but only P-band representing the true understorey surface. I will present some of the recent highlights of topography on Mars including 3D modelling of surface shape from the ESA Mars Express HRSC (High Resolution Stereo Camera), see [1], [2] at 30-100m grid-spacing; and then co-registered to HRSC using a resolution cascade of 20m DTMs from NASA MRO stereo-CTX and 0.75m digital terrain models (as there is no land cover on Mars) DTMs from MRO stereo-HiRISE [3]. Comparable DTMs now exist for the Moon from 100m up to 1m. I will show examples of these DEM/DTM datasets

  13. Bubble-based acoustic micropropulsors: active surfaces and mixers.

    PubMed

    Bertin, Nicolas; Spelman, Tamsin A; Combriat, Thomas; Hue, Hervé; Stéphan, Olivier; Lauga, Eric; Marmottant, Philippe

    2017-04-11

    Acoustic micropropulsors present great potential for microfluidic applications. The propulsion is based on encapsulated 20 μm bubbles excited by a contacless ultrasonic transducer. The vibrating bubbles then generate a powerful streaming flow, with speeds 1-100 mm s(-1) in water, through the action of viscous stresses. In this paper we introduce a full toolbox of micropropulsors using a versatile three-dimensional (3D) microfabrication setup. Doublets and triplets of propulsors are introduced, and the flows they generate are predicted by a theoretical hydrodynamic model. We then introduce whole surfaces covered with propulsors, which we term active surfaces. These surfaces are excited by a single ultrasonic wave, can generate collective flows and may be harnessed for mixing purposes. Several patterns of propulsors are tested, and the flows produced by the two most efficient mixers are predicted by a simple theoretical model based on flow singularities. In particular, the vortices generated by the most efficient pattern, an L-shaped mixer, are analysed in detail.

  14. Complex copolymers for mobility control, water purification, and surface activity

    SciTech Connect

    Meister, J.J.

    1988-05-01

    Many processes that are basic to the extraction of natural resources are facilitated by addition of polymers. To be useful, the polymers must meet an interrelated list of chemical and physical properties as well as economic criteria. Two important properties demanded of the polymers are: 1. Rheology. Polymers are often added to change solvent or process flow properties. The addition of polymers almost always causes non-Newtonian flow behavior in the resulting fluid. Methods of controlling surface behavior are to: 1) create polar and nonpolar regions in the molecule thus producing a hydrophilic-lipophilic balance in the molecule, 2) charge the molecule by introducing ionic sites with the same or opposite charge as the boundary, or 3) introduce or remove functional groups in the molecule which produce binding reactions, such as a) hydrogen bond creation of b) nitrogen lone-pair donation, with the surface. This multitude of properties the polymer must possess dictate that better polymer performance is obtained from materials with complicated structures. Such polymers are complex polymers: random copolymers, block copolymers, graft copolymers, micellizing copolymers, and network copolymers. There has been a dramatic increase in the past decade in the number and complexity of these copolymers and it is these newly discovered polymers and their chemistry which will be described here. The synthesis, analysis, and testing of these polymers, with particular emphasis on those polymers designed for enhanced oil recovery, is presented.

  15. Pioneering Objectives and Activities on the Surface of Mars

    NASA Technical Reports Server (NTRS)

    Toups, Larry; Hoffman, Stephen J.

    2015-01-01

    Human Mars missions have been a topic of sustained interest within NASA, which continues to use its resources to examine many different mission objectives, trajectories, vehicles, and technologies, the combinations of which are often referred to as reference missions or architectures. The current investigative effort, known as the Evolvable Mars Campaign (EMC), is examining alternatives that can pioneer an extended human presence on Mars that is Earth independent. These alternatives involve combinations of all the factors just mentioned. This paper is focused on the subset of these factors involved with objectives and activities that take place on the surface of Mars. "Pioneering" is a useful phrase to encapsulate the current approach being used to address this situation - one of its primary definitions is "a person or group that originates or helps open up a new line of thought or activity or a new method or technical development". Thus, in this scenario, NASA would be embarking on a path to "pioneer" a suite of technologies and operations that will result in an Earth independent, extended stay capability for humans on Mars. This paper will describe (a) the concept of operation determined to be best suited for the initial emplacement, (b) the functional capabilities determined to be necessary for this emplacement, with representative examples of systems that could carry out these functional capabilities and one implementation example (i.e., delivery sequence) at a representative landing site, and will (c) discuss possible capabilities and operations during subsequent surface missions.

  16. Statistical and signal-processing concepts in surface metrology

    SciTech Connect

    Church, E.L.; Takacs, P.Z.

    1986-03-01

    This paper proposes the use of a simple two-scale model of surface roughness for testing and specifying the topographic figure and finish of synchrotron-radiation mirrors. In this approach the effects of figure and finish are described in terms of their slope distribution and power spectrum, respectively, which are then combined with the system point spread function to produce a composite image. The result can be used to predict mirror performance or to translate design requirements into manufacturing specifications. Pacing problems in this approach are the development of a practical long-trace slope-profiling instrument and realistic statistical models for figure and finish errors.

  17. Surface Modification of Biomedical and Dental Implants and the Processes of Inflammation, Wound Healing and Bone Formation

    PubMed Central

    Stanford, Clark M.

    2010-01-01

    Bone adaptation or integration of an implant is characterized by a series of biological reactions that start with bone turnover at the interface (a process of localized necrosis), followed by rapid repair. The wound healing response is guided by a complex activation of macrophages leading to tissue turnover and new osteoblast differentiation on the implant surface. The complex role of implant surface topography and impact on healing response plays a role in biological criteria that can guide the design and development of future tissue-implant surface interfaces. PMID:20162020

  18. Microwave Processing of Planetary Surfaces for Volatile Extraction

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Kaukler, William

    2011-01-01

    In-Situ Resource Utilization will be necessary for sustained exploration of space. Volatiles are present in planetary soils, but water by far has the strongest potential for effective utilization. The presence of water at the lunar poles, Mars, and possibly on Phobos opens the possibility of producing LOX for propellant. Water is also a useful radiation shielding material and water (and oxygen) are expendables that are also required for habitation in space. Because of the strong function of water vapor pressure with temperature, heating soil effectively liberates water vapor by sublimation. Microwave energy will penetrate soil and heat from within much more efficiently than heating from the surface with radiant heat. This is especially true under vacuum conditions since the heat transfer rate is very low. The depth of microwave penetration is a strong function of the microwave frequency and to a lesser extent on soil dielectric properties. Methods for measuring the complex electric permittivity and magnetic permeability are being developed and have been measured for some lunar soil simulants at 0.5, 2.45, and 10 GHz from room temperature down to liquid nitrogen temperature. A new method for delivery of microwaves deep into a planetary surface is being prototyped with laboratory experiments and modeled with COMSOL MultiPhysics. We have plans to set up a planetary testbed in a large vacuum chamber in the coming year. Recent results will be presented.

  19. Microwave Processing of Planetary Surfaces for the Extraction of Volatiles

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Kaukler, William

    2011-01-01

    In-Situ Resource Utilization will be necessary for sustained exploration of space. Volatiles are present in planetary soils, but water by far has the most potential for effective utilization. The presence of water at the lunar poles, Mars, and possibly on Phobos opens the possibility of producing LOX for propellant. Water is also a useful radiation shielding material , and valuable to replenish expendables (water and oxygen) required for habitation in space. Because of the strong function of water vapor pressure with temperature, heating soil effectively liberates water vapor by sublimation. Microwave energy will penetrate soil and heat from within much more efficiently than heating from the surface with radiant heat. This is especially true under vacuum conditions since the heat transfer rate is very low. The depth of microwave penetration is a strong function of the microwave frequency and to a lesser extent on soil dielectric properties. Methods for complex electric permittivity and magnetic permeability measurement are being developed and used for measurements of lunar soil simulants. A new method for delivery of microwaves deep into a planetary surface is being prototyped with laboratory experiments and modeled with COMSOL MultiPhysics. We are planning to set up a planetary testbed in a large vacuum chamber in the coming year. Recent results are discussed.

  20. Integrated Water Flow Model (IWFM), A Tool For Numerically Simulating Linked Groundwater, Surface Water And Land-Surface Hydrologic Processes

    NASA Astrophysics Data System (ADS)

    Dogrul, E. C.; Brush, C. F.; Kadir, T. N.

    2006-12-01

    The Integrated Water Flow Model (IWFM) is a comprehensive input-driven application for simulating groundwater flow, surface water flow and land-surface hydrologic processes, and interactions between these processes, developed by the California Department of Water Resources (DWR). IWFM couples a 3-D finite element groundwater flow process and 1-D land surface, lake, stream flow and vertical unsaturated-zone flow processes which are solved simultaneously at each time step. The groundwater flow system is simulated as a multilayer aquifer system with a mixture of confined and unconfined aquifers separated by semiconfining layers. The groundwater flow process can simulate changing aquifer conditions (confined to unconfined and vice versa), subsidence, tile drains, injection wells and pumping wells. The land surface process calculates elemental water budgets for agricultural, urban, riparian and native vegetation classes. Crop water demands are dynamically calculated using distributed soil properties, land use and crop data, and precipitation and evapotranspiration rates. The crop mix can also be automatically modified as a function of pumping lift using logit functions. Surface water diversions and groundwater pumping can each be specified, or can be automatically adjusted at run time to balance water supply with water demand. The land-surface process also routes runoff to streams and deep percolation to the unsaturated zone. Surface water networks are specified as a series of stream nodes (coincident with groundwater nodes) with specified bed elevation, conductance and stage-flow relationships. Stream nodes are linked to form stream reaches. Stream inflows at the model boundary, surface water diversion locations, and one or more surface water deliveries per location are specified. IWFM routes stream flows through the network, calculating groundwater-surface water interactions, accumulating inflows from runoff, and allocating available stream flows to meet specified or

  1. Surface processes on a mud-dominated Mars analogue alluvial fan, Atacama Desert, northern Chile

    NASA Astrophysics Data System (ADS)

    Hobley, D. E.; Howard, A. D.; Morgan, A. M.; Matsubara, Y.; Moore, J. M.; Parsons, R.; Williams, R. M.; Burr, D. M.; Hayes, A. G.; Dietrich, W.

    2012-12-01

    We characterize surface processes on highly unusual terrestrial alluvial fans, which we interpret as a strong analogue for large fans on Mars. The Mars fans date to post-Noachian periods when the martian climate was dominated by cold, hyperarid conditions. Some of the martian fans are differentially eroded to leave their distributary channels in positive relief. This inversion, along with the lack of boulders visible on most fan surfaces, reveals that the dominant grain size of the fans is fine enough for the overbank deposits to be stripped by wind. Degradation, image resolution, and lack of ground truthing all act to obscure the nature of the past flow processes. The fans in the Pampa de Tamarugal of the Atacama Desert of northern Chile are excellent potential Mars analogues for a number of reasons: 1. Hyperaridity, with ~2 mm/y rainfall over the fans themselves, resulting in 2. very little vegetation, 3. no fluvial erosion on the fans themselves, and 4. wind-driven erosion of the fan surfaces; 5. equivalent fan scale (tens of km); 6. similar fan gradient (low); 7. low channel branching density; 8. runoff fed from adjacent, much steeper terrain receiving more precipitation (~500 km2 drainages receiving 0.1-1 m/y precipitation in the High Andes, crater walls and interpreted orographic effects on Mars). Both the modern channels and the preserved stratigraphy are dominated by debris flow-like sheetflow mud deposits. Channels are leveed by concrete-like mass-supported deposits of granules and sand suspended in a silt and clay matrix, often overtopping the channel margins and forming up to 150 m wide levees and km-length sheet flows. This leveeing strongly constrains the aggrading channel, which is typically dominated by better sorted and imbricated fluvial deposits. We infer that the wetter tail of mudlfows sorts the deposits, keeping the central channel unblocked by mud. Relatively few channels are active at any time, but aggradation triggers occasional avulsions

  2. Redistribution of the fibrinogen receptor of human platelets after surface activation

    PubMed Central

    1984-01-01

    We investigated the whole cell distribution of the platelet membrane receptor for fibrinogen in surface-activated human platelets. Fibrinogen-labeled colloidal gold was used in conjunction with platelet whole mount preparations to visualize directly the fibrinogen receptor. Unstimulated platelets fail to bind fibrinogen, and binding was minimal in the stages of activation immediately following adhesion. The amount of fibrinogen bound per platelet increased rapidly during the shape changes associated with surface activation until 7,600 +/- 500 labels were present at saturation. Maximal binding of fibrinogen was followed by receptor redistribution. During the early stages of spreading, fibrinogen labels were uniformly distributed over the entire platelet surface, including pseudopodia, but the labels become progressively centralized as the spreading process continued. In well spread platelets, labels were found over the central regions, whereas peripheral areas were cleared of receptors. Receptor redistribution during spreading was accompanied by cytoskeletal reorganization such that a direct correlation was seen between the development of specific ultrastructural zones and the distribution of surface receptor sites suggesting a link between the surface receptors and the cytoskeleton. The association of fibrinogen receptors with contractile elements of the cytoskeleton, which permits coordinated receptor centralization, is important to the understanding of the role of fibrinogen in normal platelet aggregation and clot retraction. PMID:6088559

  3. Inhibition of cell surface mediated plasminogen activation by a monoclonal antibody against alpha-Enolase.

    PubMed

    López-Alemany, Roser; Longstaff, Colin; Hawley, Stephen; Mirshahi, Massoud; Fábregas, Pere; Jardí, Merce; Merton, Elizabeth; Miles, Lindsey A; Félez, Jordi

    2003-04-01

    Localization of plasmin activity on leukocyte surfaces plays a critical role in fibrinolysis as well as in pathological and physiological processes in which cells must degrade the extracellular matrix in order to migrate. The binding of plasminogen to leukocytic cell lines induces a 30- to 80-fold increase in the rate of plasminogen activation by tissue-type (tPA) and urokinase-type (uPA) plasminogen activators. In the present study we have examined the role of alpha-enolase in plasminogen activation on the cell surface. We produced and characterized a monoclonal antibody (MAb) 11G1 against purified alpha-enolase, which abrogated about 90% of cell-dependent plasminogen activation by either uPA or tPA on leukocytoid cell lines of different lineages: B-lymphocytic, T-lymphocytic, granulocytic, and monocytic cells. In addition, MAb 11G1 also blocked enhancement of plasmin formation by peripheral blood neutrophils and monocytes. In contrast, MAb 11G1 did not affect plasmin generation in the presence of fibrin, indicating that this antibody did not interact with fibrinolytic components in the absence of cells. These data suggest that, although leukocytic cells display several molecules that bind plasminogen, alpha-enolase is responsible for the majority of the promotion of plasminogen activation on the surfaces of leukocytic cells.

  4. Adsorption-induced changes in ribonuclease A structure and enzymatic activity on solid surfaces.

    PubMed

    Wei, Yang; Thyparambil, Aby A; Wu, Yonnie; Latour, Robert A

    2014-12-16

    Ribonuclease A (RNase A) is a small globular enzyme that lyses RNA. The remarkable solution stability of its structure and enzymatic activity has led to its investigation to develop a new class of drugs for cancer chemotherapeutics. However, the successful clinical application of RNase A has been reported to be limited by insufficient stability and loss of enzymatic activity when it was coupled with a biomaterial carrier for drug delivery. The objective of this study was to characterize the structural stability and enzymatic activity of RNase A when it was adsorbed on different surface chemistries (represented by fused silica glass, high-density polyethylene, and poly(methyl-methacrylate)). Changes in protein structure were measured by circular dichroism, amino acid labeling with mass spectrometry, and in vitro assays of its enzymatic activity. Our results indicated that the process of adsorption caused RNase A to undergo a substantial degree of unfolding with significant differences in its adsorbed structure on each material surface. Adsorption caused RNase A to lose about 60% of its native-state enzymatic activity independent of the material on which it was adsorbed. These results indicate that the native-state structure of RNase A is greatly altered when it is adsorbed on a wide range of surface chemistries, especially at the catalytic site. Therefore, drug delivery systems must focus on retaining the native structure of RNase A in order to maintain a high level of enzymatic activity for applications such as antitumor chemotherapy.

  5. 30 CFR 921.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... surface coal mining operations. 921.764 Section 921.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS... Coal Mining Operations, pertaining to petitioning, initial processing, hearing requirements,...

  6. 30 CFR 921.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... surface coal mining operations. 921.764 Section 921.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS... Coal Mining Operations, pertaining to petitioning, initial processing, hearing requirements,...

  7. 30 CFR 933.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... surface coal mining operations. 933.764 Section 933.764 Mineral Resources OFFICE OF SURFACE MINING... Coal Mining Operations, pertaining to petitioning, initial processing, hearing requirements, decisions... surface coal mining and reclamation operations beginning one year after the effective date of this program....

  8. 30 CFR 933.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... surface coal mining operations. 933.764 Section 933.764 Mineral Resources OFFICE OF SURFACE MINING... Coal Mining Operations, pertaining to petitioning, initial processing, hearing requirements, decisions... surface coal mining and reclamation operations beginning one year after the effective date of this program....

  9. 30 CFR 921.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... surface coal mining operations. 921.764 Section 921.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS... Coal Mining Operations, pertaining to petitioning, initial processing, hearing requirements,...

  10. 30 CFR 933.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... surface coal mining operations. 933.764 Section 933.764 Mineral Resources OFFICE OF SURFACE MINING... Coal Mining Operations, pertaining to petitioning, initial processing, hearing requirements, decisions... surface coal mining and reclamation operations beginning one year after the effective date of this program....

  11. 30 CFR 921.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... surface coal mining operations. 921.764 Section 921.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS... Coal Mining Operations, pertaining to petitioning, initial processing, hearing requirements,...

  12. 30 CFR 933.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... surface coal mining operations. 933.764 Section 933.764 Mineral Resources OFFICE OF SURFACE MINING... Coal Mining Operations, pertaining to petitioning, initial processing, hearing requirements, decisions... surface coal mining and reclamation operations beginning one year after the effective date of this program....

  13. 30 CFR 933.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... surface coal mining operations. 933.764 Section 933.764 Mineral Resources OFFICE OF SURFACE MINING... Coal Mining Operations, pertaining to petitioning, initial processing, hearing requirements, decisions... surface coal mining and reclamation operations beginning one year after the effective date of this program....

  14. 30 CFR 921.764 - Process for designating areas unsuitable for surface coal mining operations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... surface coal mining operations. 921.764 Section 921.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS... mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for...

  15. Threshold processes of sodium ion emission from NaAu surface alloy

    NASA Astrophysics Data System (ADS)

    Knat'ko, M. V.; Lapushkin, M. N.

    2015-04-01

    We have studied threshold processes of Na+ ion emission from a semiconductor Na x Au y film formed on the surface of a gold substrate. In contrast to the classical notions of threshold processes involved in the surface ionization of alkali metal ions from heated metal surfaces, the diffusion exchange of atomic species between the surface and volume of the Na x Au y film ensures stable emission of Na+ ions from the substrate in the region of threshold temperatures. A diffusion mechanism of self-regulation of the surface coverage of alkali metal in the Na x Au y film is proposed.

  16. Surface gas-exchange processes of snow algae

    PubMed Central

    Williams, William E.; Gorton, Holly L.; Vogelmann, Thomas C.

    2003-01-01

    The red-colored chlorophyte Chlamydomonas nivalis is commonly found in summer snowfields. We used a modified Li-Cor gas-exchange system to investigate surface gas-exchange characteristics of snow colonized by this alga, finding rates of CO2 uptake up to 0.3 μmol m−2⋅s−1 in dense algal blooms. Experiments varying the irradiance resulted in light curves that resembled those of the leaves of higher plants. Red light was more effective than white and much more effective than green or blue, because of the red astaxanthin that surrounds and masks the algal chloroplasts. Integrating daily course measurements of gas exchange showed CO2 uptake around 2,300 μmol⋅m−2⋅day−1 in heavily colonized patches, indicating that summer snowfields can be surprisingly productive. PMID:12518048

  17. Surface conductivity dependent dynamic behaviour of an ultrafine atmospheric pressure plasma jet for microscale surface processing

    NASA Astrophysics Data System (ADS)

    Abuzairi, Tomy; Okada, Mitsuru; Bhattacharjee, Sudeep; Nagatsu, Masaaki

    2016-12-01

    An experimental study on the dynamic behaviour of microcapillary atmospheric pressure plasma jets (APPJs) with 5 μm tip size for surfaces of different conductivity is reported. Electrical and spatio-temporal characteristics of the APPJs are monitored using high voltage probe, current monitor and high speed intensified charge couple device camera. From these experimental results, we presented a simple model to understand the electrical discharge characteristics of the capillary APPJs with double electrodes, and estimated the velocity of the ionization fronts in the jet and the electron density to be 3.5-4.2 km/s and 2-7 × 1017 m-3. By analyzing the dynamics of the microcapillary APPJs for different substrate materials, it was found that the surface irradiation area strongly depended on the substrate conductivity and permittivity, especially in the case of polymer-like substrate, surface irradiation area was significantly broadened probably due to the repelling behaviour of the plasma jets from the accumulated electrical charges on the polymer surface. The effect of applying a substrate bias in the range from -900 V to +900 V on the plasma irradiation onto the substrates was also investigated. From the knowledge of the present results, it is helpful for choosing the substrate materials for microscale surface modification.

  18. A review on the application of peening processes for surface treatment

    NASA Astrophysics Data System (ADS)

    Azhari, A.; Sulaiman, S.; Prasada Rao, A. K.

    2016-02-01

    In today's practice, mechanical surface treatments have been widely applied particularly in the automotive and aerospace industries. It was realized that the failure due to fatigue depends on many factors, and very often it develops from particular surface areas of engineering parts. So, it seems possible to improve the fatigue strength of metallic components by the application of suitable mechanical surface strengthening processes. Peening processes are widely employed in industry for inducing compressive stresses on the metallic surfaces. The present work discusses the basic concepts and their applications of main peening processes namely the shot peening and the laser shock peening. Also, a recently introduced liquid jet peening is discussed.

  19. 'Scaling' analysis of the ice accretion process on aircraft surfaces

    NASA Technical Reports Server (NTRS)

    Keshock, E. G.; Tabrizi, A. H.; Missimer, J. R.

    1982-01-01

    A comprehensive set of scaling parameters is developed for the ice accretion process by analyzing the energy equations of the dynamic freezing zone and the already frozen ice layer, the continuity equation associated with supercooled liquid droplets entering into and impacting within the dynamic freezing zone, and energy equation of the ice layer. No initial arbitrary judgments are made regarding the relative magnitudes of each of the terms. The method of intrinsic reference variables in employed in order to develop the appropriate scaling parameters and their relative significance in rime icing conditions in an orderly process, rather than utilizing empiricism. The significance of these parameters is examined and the parameters are combined with scaling criteria related to droplet trajectory similitude.

  20. Surface Modified Particles By Multi-Step Michael-Type Addition And Process For The Preparation Thereof

    SciTech Connect

    Cook, Ronald Lee; Elliott, Brian John; Luebben, Silvia DeVito; Myers, Andrew William; Smith, Bryan Matthew

    2005-05-03

    A new class of surface modified particles and a multi-step Michael-type addition surface modification process for the preparation of the same is provided. The multi-step Michael-type addition surface modification process involves two or more reactions to compatibilize particles with various host systems and/or to provide the particles with particular chemical reactivities. The initial step comprises the attachment of a small organic compound to the surface of the inorganic particle. The subsequent steps attach additional compounds to the previously attached organic compounds through reactive organic linking groups. Specifically, these reactive groups are activated carbon—carbon pi bonds and carbon and non-carbon nucleophiles that react via Michael or Michael-type additions.

  1. The Multi-Temporal Database of Planetary Image Data (MUTED): A database to support the identification of surface changes and short-lived surface processes

    NASA Astrophysics Data System (ADS)

    Erkeling, G.; Luesebrink, D.; Hiesinger, H.; Reiss, D.; Heyer, T.; Jaumann, R.

    2016-06-01

    Images of Mars taken by spacecraft in the last few decades indicate that the landscape has changed and that current processes are continuously changing the surface. The modifications of the landscape are caused by exogenic processes including eolian activity, mass movement, the growth and retreat of the polar caps, glacial processes and crater-forming impacts. In particular the High Resolution Stereo Camera (HRSC) on board Mars Express (MEx) and the Context Camera (CTX) on board the Mars Reconnaissance Orbiter (MRO) cover large areas at high resolution and thus are particularly well-suited to detect the extent and origin of surface changes on Mars. Multi-temporal observations of variable features on Mars became possible by the increasing number of repeated image acquisitions of the same surface areas. To support the investigation of surface changes that represents a key element in martian research, we developed MUTED, the "Multi-Temporal Database of Planetary Image Data", which is a tool for the identification of the spatial and multi-temporal coverage of planetary image data from Mars. Using MUTED, scientists are able to identify the location, number, and time range of acquisitions of overlapping images from, for example, HRSC and CTX. MUTED also includes images from other planetary datasets such as those of the Mars Orbiter Camera (MOC), the Thermal Emission Imaging System (THEMIS), and the High Resolution Imaging Science Experiment (HiRISE). The database supports the identification and analysis of surface changes and short-lived surface processes on Mars based on fast automatic planetary image database queries. From the multi-temporal planetary image database and investigations based on multi-temporal observations we will better understand the interactions between the surface of Mars and external forces, including the atmosphere. MUTED is available for the planetary scientific community via the webpage of the Institut für Planetologie (IfP) Muenster.

  2. Active-site titration analysis of surface influence on immobilized Candida antarctica Lipase B activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Matrix morphology and surface polarity effects were investigated for Candida antarctica lipase B immobilization. Measurements of the amount of lipase immobilized (bicinchoninic acid method) and the catalyst’s tributyrin hydrolysis activity, coupled with a determination of the lipase’s functional fr...

  3. Mesopore control of high surface area NaOH-activated carbon.

    PubMed

    Tseng, Ru-Ling

    2006-11-15

    Activated carbon with BET surface areas in a narrow range from 2318 to 2474 m2/g was made by soaking the char made from corncob in a concentrated NaOH solution at NaOH/char ratios from 3 to 6; the mesopore volumes of the activated carbon were significantly changed from 21 to 58%. The relationships between pore properties (Sp, Vpore, Vmicro/Vpore, Dp) and NaOH dosage were investigated. Comparisons between the methods of NaOH and KOH activation revealed that NaOH activation can suitably control the mesopore specific volume of the activated carbon. Elemental analysis revealed that the H/C and O/C values of the activated carbons of NaOH/char ratios from 3 to 6 were significantly lower. SEM observation of surface hole variation of the activated carbon ascertained that the reaction process was inner pore etching. Based on the above three measurements and experimental investigations, the assumption made by previous researchers, namely that NaOH and KOH produce similar results, was challenged. Furthermore, the adsorption kinetics was used to investigate the adsorption rate of an Elovich equation to determine the relationships between the adsorption behavior on larger molecules (dyes) and smaller molecules (phenols) and the pore structure of the activated carbon.

  4. Controlled release of biologically active silver from nanosilver surfaces.

    PubMed

    Liu, Jingyu; Sonshine, David A; Shervani, Saira; Hurt, Robert H

    2010-11-23

    Major pathways in the antibacterial activity and eukaryotic toxicity of nanosilver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nanosilver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nanosilver is widely recognized, the drug delivery paradigm has not been well developed for this system, and there is significant potential to improve nanosilver technologies through controlled release formulations. This article applies elements of the drug delivery paradigm to nanosilver dissolution and presents a systematic study of chemical concepts for controlled release. After presenting thermodynamic calculations of silver species partitioning in biological media, the rates of oxidative silver dissolution are measured for nanoparticles and macroscopic foils and used to derive unified area-based release kinetics. A variety of competing chemical approaches are demonstrated for controlling the ion release rate over 4 orders of magnitude. Release can be systematically slowed by thiol and citrate ligand binding, formation of sulfidic coatings, or the scavenging of peroxy-intermediates. Release can be accelerated by preoxidation or particle size reduction, while polymer coatings with complexation sites alter the release profile by storing and releasing inventories of surface-bound silver. Finally, the ability to tune biological activity is demonstrated through a bacterial inhibition zone assay carried out on selected formulations of controlled release nanosilver.

  5. Photoresist surface roughness characterization in additive lithography processes for fabrication of phase-only optical vortices

    NASA Astrophysics Data System (ADS)

    Poutous, Menelaos K.; Hosseinimakarem, Zahra; Johnson, Eric G.

    2012-10-01

    Roughness on the surface of phase-only micro-optical elements limits their performance. An optical vortex phase element was fabricated, using additive lithography, with an optimized process to achieve minimal surface roughness. Shipley S1827 photoresist was used in order to obtain the appropriate additive lithography dynamic range for the desired phase profile. We investigated the effects of both postapplied and postexposure baking processes, bias exposure dose, as well as the effects of surfactant in the developer. We found the resist surface roughness to be a function of both the temperature and the time of the postapplication baking cycles, as well as the developer surfactant content. Based on our findings, an empirical correlation model was constructed to relate the process parameters with surface roughness measured quantities. The maximum roughness of the optical surface, for the optimized process, was reduced to 40 percent of the value for the unoptimized process and the additive lithography useful exposure range was increased by 10 percent.

  6. Process of activation of a palladium catalyst system

    SciTech Connect

    Sobolevskiy, Anatoly; Rossin, Joseph A.; Knapke, Michael J.

    2011-08-02

    Improved processes for activating a catalyst system used for the reduction of nitrogen oxides are provided. In one embodiment, the catalyst system is activated by passing an activation gas stream having an amount of each of oxygen, water vapor, nitrogen oxides, and hydrogen over the catalyst system and increasing a temperature of the catalyst system to a temperature of at least 180.degree. C. at a heating rate of from 1-20.degree./min. Use of activation processes described herein leads to a catalyst system with superior NOx reduction capabilities.

  7. Deposition of substituted apatites with anticolonizing properties onto titanium surfaces using a novel blasting process.

    PubMed

    O'Sullivan, C; O'Hare, P; O'Leary, N D; Crean, A M; Ryan, K; Dobson, A D W; O'Neill, L

    2010-10-01

    A series of doped apatites have been deposited onto titanium (V) substrates using a novel ambient temperature blasting process. The potential of these deposited doped apatites as non-colonizing osteoconductive coatings has been evaluated in vitro. XPS, EDX, and gravimetric analysis demonstrated that a high degree of coating incorporation was observed for each material. The modified surfaces were found to produce osteoblast proliferation comparable to, or better than, a hydroxyapatite finish. Promising levels of initial microbial inhibition were observed from the Sr- and Ag-doped surfaces, with the strontium showing prolonged ability to reduce bacteria numbers over a 30-day period. Ion elution profiles have been characterized and linked to the microbial response and based on the results obtained, mechanisms of kill have been suggested. In this study, the direct contact of coated substrate surfaces with microbes was observed to be a significant contributing factor to the antimicrobial performance and the anticolonizing activity. The silver substituted apatite was observed to out-perform both the SrA and ZnA in terms of biofilm inhibition.

  8. Experimental progress with novel surface electrode ion trap structures for quantum information processing

    NASA Astrophysics Data System (ADS)

    Clark, Craig; Blain, Matthew; Benito, Francisco; Chou, Chin-Wen; Descour, Mike; Ellis, Rob; Haltli, Ray; Heller, Edwin; Kemme, Shanalyn; Sterk, Jon; Tabakov, Boyan; Tigges, Chris; Maunz, Peter; Stick, Daniel

    2013-05-01

    Segmented surface electrode ion traps are one of the most mature platforms among candidates for scalable quantum information processing. In this poster, an overview of current results from four specific projects will be presented. Two projects involve increased light collection from trapped ion for state detection and/or remote entangling of distant ions. The first involves cavity integration into a linear surface trap, and the second, involves integration of diffractive optical elements into a linear surface trap for increased light collection. Another project involves a trap with a ring geometry which could be used to trap long chains of equally spaced ions. Finally, we report on initial testing of a trap structure with vastly improved in-plane optical access. In this structure in-plane beams can be focused to less than 8 microns while keeping a distance of at least 5 beam radii to the trap structure. Along with these projects other relevant progress from Sandia National Laboratory's ion trap group will be presented. This work was supported by Sandia's Laboratory Directed Research and Development (LDRD) and the Intelligence Advanced Research Projects Activity (IARPA). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  9. Seismoelectric data processing for surface surveys of shallow targets

    USGS Publications Warehouse

    Haines, S.S.; Guitton, A.; Biondi, B.

    2007-01-01

    The utility of the seismoelectric method relies on the development of methods to extract the signal of interest from background and source-generated coherent noise that may be several orders-of-magnitude stronger. We compare data processing approaches to develop a sequence of preprocessing and signal/noise separation and to quantify the noise level from which we can extract signal events. Our preferred sequence begins with the removal of power line harmonic noise and the use of frequency filters to minimize random and source-generated noise. Mapping to the linear Radon domain with an inverse process incorporating a sparseness constraint provides good separation of signal from noise, though it is ineffective on noise that shows the same dip as the signal. Similarly, the seismoelectric signal and noise do not separate cleanly in the Fourier domain, so f-k filtering can not remove all of the source-generated noise and it also disrupts signal amplitude patterns. We find that prediction-error filters provide the most effective method to separate signal and noise, while also preserving amplitude information, assuming that adequate pattern models can be determined for the signal and noise. These Radon-domain and prediction-error-filter methods successfully separate signal from <33 dB stronger noise in our test data. ?? 2007 Society of Exploration Geophysicists.

  10. Development of thermally processed nanocomposites with controlled surfaces

    NASA Astrophysics Data System (ADS)

    Georgieva, Petya

    The ever increasing need for technology development requires the integration of inexpensive, light weight and high strength materials which are able to meet the high standards and specifications for various engineering applications. The intention of this work is to show that the suitable material selection and the utilization of plasma spray processing can be of potential interest to a large number of industrial, biomedical and everyday life applications. This research demonstrates also that plasma processing is a promising engineering tool for multifunctional coatings and near-net-shape manufacturing. Further, the theoretical and experimental results are combined in order to explain the mechanisms behind nanostructure retention and enhanced properties. Proper design of experiments, an appropriate material selection and experimental methodology are discussed herein. The experimental conditions were optimized in order to achieve the best materials properties according to their explicit properties and functions. Specific materials were consolidated according to their prospective performance and applications: (1) Plasma spraying of nano-Ceria-stabilized Zirconia free form part for stem cells scaffolds, (2) Plasma spraying of FeCrAlY on Ti-alloy plate, additionally coated with nano-size Hydroxyapatite for bone tissue engineering, (3) Wire-arc spraying of nano-based steel wires for aerospace and automotive applications. The performance and characteristics of all of the developed coatings and free-form-parts are evaluated using state-of-the art characterization techniques.

  11. Effect of particle surface area on ice active site densities retrieved from droplet freezing spectra

    NASA Astrophysics Data System (ADS)

    Beydoun, Hassan; Polen, Michael; Sullivan, Ryan C.

    2016-10-01

    Heterogeneous ice nucleation remains one of the outstanding problems in cloud physics and atmospheric science. Experimental challenges in properly simulating particle-induced freezing processes under atmospherically relevant conditions have largely contributed to the absence of a well-established parameterization of immersion freezing properties. Here, we formulate an ice active, surface-site-based stochastic model of heterogeneous freezing with the unique feature of invoking a continuum assumption on the ice nucleating activity (contact angle) of an aerosol particle's surface that requires no assumptions about the size or number of active sites. The result is a particle-specific property g that defines a distribution of local ice nucleation rates. Upon integration, this yields a full freezing probability function for an ice nucleating particle. Current cold plate droplet freezing measurements provide a valuable and inexpensive resource for studying the freezing properties of many atmospheric aerosol systems. We apply our g framework to explain the observed dependence of the freezing temperature of droplets in a cold plate on the concentration of the particle species investigated. Normalizing to the total particle mass or surface area present to derive the commonly used ice nuclei active surface (INAS) density (ns) often cannot account for the effects of particle concentration, yet concentration is typically varied to span a wider measurable freezing temperature range. A method based on determining what is denoted an ice nucleating species' specific critical surface area is presented and explains the concentration dependence as a result of increasing the variability in ice nucleating active sites between droplets. By applying this method to experimental droplet freezing data from four different systems, we demonstrate its ability to interpret immersion freezing temperature spectra of droplets containing variable particle concentrations. It is shown that general

  12. PROCESSING, MICROSTRUCTURE AND MECHANICAL PROPERTY CORRELATION IN Al-B4C SURFACE COMPOSITE PRODUCED VIA FRICTION STIR PROCESSING

    SciTech Connect

    Komarasamy, Mageshwari; Mishra, Rajiv S.; Baumann, John A.; Grant, Glenn J.; Hovanski, Yuri

    2013-01-29

    Friction stir processing (FSP) was employed to prepare surface composites (SC) composed of B4C particles in 5024 Al matrix. The processing parameters, such as hole pattern and geometry,and the number of FSP passes, were optimized to obtain uniform powder distribution. The micrographs revealed a homogeneous distribution of the particles with good interfacial bonding. The hardness of the composite was uniform across the processed region which again indicates the uniformity of powder distribution. The modulus of the surface composite was measured using strain gage and showed a significant improvement. This improvement in modulus lies in the load sharing capability from the soft matrix to the hard particles.

  13. Mechanical stress-controlled tunable active frequency-selective surface

    NASA Astrophysics Data System (ADS)

    Huang, Bo-Cin; Hong, Jian-Wei; Lo, Cheng-Yao

    2017-01-01

    This study proposes a tunable active frequency-selective surface (AFSS) realized by mechanically expanding or contracting a split-ring resonator (SRR) array. The proposed AFSS transfers mechanical stress from its elastic substrate to the top of the SRR, thereby achieving electromagnetic (EM) modulation without the need for an additional external power supply, meeting the requirements for the target application: the invisibility cloak. The operating mechanism of the proposed AFSS differs from those of other AFSSs, supporting modulations in arbitrary frequencies in the target range. The proposed stress-controlled or strain-induced EM modulation proves the existence of an identical and linear relationship between the strain gradient and the frequency shift, implying its suitability for other EM modulation ranges and applications.

  14. Activation of carbon dioxide on metal and metal oxide surfaces

    SciTech Connect

    Tan, C.D.; Chuang, S.S.C.

    1995-12-31

    The environmental concern about the impact of CO{sub 2} has grown recently due to its rapidly increasing concentration. Deforestation strongly affects the natural reduction of CO{sub 2} by water into carbohydrates by photosynthesis. Industrial utilization of CO{sub 2} by heterogeneous catalytic reactions can be one of the effective ways to cut the CO{sub 2} level. The first step in catalytic reaction of CO{sub 2} is the adsorption. The objective of this study is to investigate the adsorption of CO{sub 2} on the Rh/Al{sub 2}O{sub 3} surfaces. Rh is selected for this study because of its unique activity to catalyze a number of CO{sub 2} related reactions. In situ infrared results show that CO{sub 2} adsorbed on the alumina oxide support as bidentate carbonate and non-coordinated carbon which are the dominant species during the CO{sub 2} adsorption.

  15. Trichomes as sensors: detecting activity on the leaf surface.

    PubMed

    Tooker, John F; Peiffer, Michelle; Luthe, Dawn S; Felton, Gary W

    2010-01-01

    The dramatic movements of some carnivorous plants species are triggered by sensory structures derived from trichomes. While unusual plant species such as the Venus fly trap and sundews may be expected to have elaborate sensors to capture their insect prey, more modest plant species might not be expected to have similar sensory capabilities. Our recent work, however, has revealed that glandular trichomes on tomato (Solanum lycopersicum) appear to have a function similar to trigger hairs of carnivorous species, acting as "early warning" sensors. Using a combination of behavioral, molecular, and biochemical techniques, we determined that caterpillars, moths and mechanical disruption upregulate signaling molecules and defensive genes found in glandular trichomes. Importantly, we discovered that plants whose trichomes have been broken respond more vigorously when their defenses were induced. Taken together, our results suggest that glandular trichomes can act as sensors that detect activity on the leaf surface, and ready plants for herbivore attack.

  16. Hold My Calls: An Activity for Introducing the Statistical Process

    ERIC Educational Resources Information Center

    Abel, Todd; Poling, Lisa

    2015-01-01

    Working with practicing teachers, this article demonstrates, through the facilitation of a statistical activity, how to introduce and investigate the unique qualities of the statistical process including: formulate a question, collect data, analyze data, and interpret data.

  17. Evaluation of Control Parameters for the Activated Sludge Process

    ERIC Educational Resources Information Center

    Stall, T. Ray; Sherrard, Josephy H.

    1978-01-01

    An evaluation of the use of the parameters currently being used to design and operate the activated sludge process is presented. The advantages and disadvantages for the use of each parameter are discussed. (MR)

  18. Processing of Enceladus' surface ice by energetic electrons, soft X-ray and VUV photons

    NASA Astrophysics Data System (ADS)

    Souza Bergantini, Alexandre; Pilling, Sergio; Jones, Brant; Kaiser, Ralf

    Enceladus is a tiny, yet extremely interesting, moon of Saturn. It presents unique features in the Solar system, such as the chemically rich icy surface and the interior driven by intense geological activity, revealed by hot spots in the Enceladus’ south pole, a region dubbed the “Tiger Stripes” (Porco et al. 2006 Science). Enceladus’ frozen surface is dominated by H_2O (both in crystalline and amorphous form) and small amounts of carbon dioxide, methane, and ammonia, among other molecules in minor concentration. These molecules held the most important single elements for life as we know (i.e. CHON). In this work we present the results from several experiments on the processing of analogue of Enceladus ice surface by energetic electrons (5 keV) and vacuum ultraviolet (VUV) photons in extreme-ultra-high vacuum regime (base pressure: 4x10(-11) mbar) in the W.M. Keck Astrochemistry laboratory in the University of Hawaii at Manoa, and the processing of the same ice by soft X-ray photons, using a high-vacuum portable chamber from the Laboratorio de Astroquimica e Astrobiologia (LASA/UNIVAP) coupled to the spherical grating monochromator (SGM) beamline, in the Brazilian Synchrotron Light Source (LNLS). The experiments consist in the irradiation of a mixture, analogue to the Enceladus' ice surface (H_2O:CO_2:CH_4:NH_3 - 10:1:1:1), in different temperatures (5.5 K, 35 K, and 72 K). The samples were produced by the adsorption of the mixture in very low temperatures (5.5 K and 12 K), and the results were analyzed by FTIR spectroscopy in the mid-infrared region (4000-400 cm(-1) or 2.5-25.0 mum range), as well as by time-of-flight mass-spectrometry (1 to 200 amu). The absolute dissociation cross sections of the parent molecules and the formation cross section of the daughter species were determined. Among the produced species, CO, OCN(-) , H_2CO, and HCONH_2 were easily detected, and the time-of-flight data shows the production of species with molecular masses up to

  19. A model for heterogeneous chemical processes on the surfaces of ice and nitric acid trihydrate particles

    NASA Technical Reports Server (NTRS)

    Tabazadeh, Azadeh; Turco, Richard P.

    1993-01-01

    The study presents a model that incorporates the physics and physical chemistry of ice surfaces relevant to polar stratospheric clouds. Surface concentrations of H2O, HCl, HOCl, ClONO2, and N2O5 on ice and nitric acid trihydrate (NAT) crystals are computed, and surface reaction rates and reaction probabilities (sticking coefficients) are determined. For gas pressures of about 10 exp -7 torr and temperatures in the range of 180-200 K, HCl completely coats ice and water-rich NAT surfaces, while HOCl, ClOHO2, and N2O5 may cover 0.01-1 percent of these surfaces. The energy parameters are used to calculate surface temperatures such as adsorption and desorption constants, surface coverages, reaction rate coefficients, surface diffusion coefficients, and reaction probabilities for various species and chemical interactions on ice and NAT surfaces. Implications for chemical processing on polar stratospheric clouds are discussed.

  20. A model for heterogeneous chemical processes on the surfaces of ice and nitric acid trihydrate particles

    NASA Astrophysics Data System (ADS)

    Tabazadeh, Azadeh; Turco, Richard P.

    1993-07-01

    The study presents a model that incorporates the physics and physical chemistry of ice surfaces relevant to polar stratospheric clouds. Surface concentrations of H2O, HCl, HOCl, ClONO2, and N2O5 on ice and nitric acid trihydrate (NAT) crystals are computed, and surface reaction rates and reaction probabilities (sticking coefficients) are determined. For gas pressures of about 10 exp -7 torr and temperatures in the range of 180-200 K, HCl completely coats ice and water-rich NAT surfaces, while HOCl, ClOHO2, and N2O5 may cover 0.01-1 percent of these surfaces. The energy parameters are used to calculate surface temperatures such as adsorption and desorption constants, surface coverages, reaction rate coefficients, surface diffusion coefficients, and reaction probabilities for various species and chemical interactions on ice and NAT surfaces. Implications for chemical processing on polar stratospheric clouds are discussed.

  1. Understanding Surface Processes on Mars Through Study of Iron Oxides/Oxyhydroxides: Clues to Surface Alteration and Aqueous Processes

    NASA Technical Reports Server (NTRS)

    Bishop, J. L.; Mancinelli, R. L.; Dyar, M. D.; Parente, M.; Drief, A.; Lane, M. D.; Murad, E.

    2006-01-01

    We are performing oxidation and reduction reactions on hydrated ferric oxide minerals in order to investigate how these might alter under a variety of conditions on the surface of Mars. Preliminary experiments on ferrihydrite and goethite showed that heating these minerals in a dry oxidizing environment produces fine-grained hematite, while heating these minerals in a reducing environment produces fine-grained magnetite. Under Mars-like oxidation levels this magnetite then oxidizes to maghemite. These reactions are dependent on the presence of water and organic material that can act as a reductant. We are using reflectance and Mossbauer spectroscopy to characterize the reaction products and TEM to analyze the sample texture. Our preliminary results indicate that magnetite and maghemite could be formed in the soil on Mars from ferrihydrite and goethite if organics were present on early Mars.

  2. Scube2 enhances proteolytic Shh processing from the surface of Shh-producing cells.

    PubMed

    Jakobs, Petra; Exner, Sebastian; Schürmann, Sabine; Pickhinke, Ute; Bandari, Shyam; Ortmann, Corinna; Kupich, Sabine; Schulz, Philipp; Hansen, Uwe; Seidler, Daniela G; Grobe, Kay

    2014-04-15

    All morphogens of the Hedgehog (Hh) family are synthesized as dual-lipidated proteins, which results in their firm attachment to the surface of the cell in which they were produced. Thus, Hh release into the extracellular space requires accessory protein activities. We suggested previously that the proteolytic removal of N- and C-terminal lipidated peptides (shedding) could be one such activity. More recently, the secreted glycoprotein Scube2 (signal peptide, cubulin domain, epidermal-growth-factor-like protein 2) was also implicated in the release of Shh from the cell membrane. This activity strictly depended on the CUB domains of Scube2, which derive their name from the complement serine proteases and from bone morphogenetic protein-1/tolloid metalloproteinases (C1r/C1s, Uegf and Bmp1). CUB domains function as regulators of proteolytic activity in these proteins. This suggested that sheddases and Scube2 might cooperate in Shh release. Here, we confirm that sheddases and Scube2 act cooperatively to increase the pool of soluble bioactive Shh, and that Scube2-dependent morphogen release is unequivocally linked to the proteolytic processing of lipidated Shh termini, resulting in truncated soluble Shh. Thus, Scube2 proteins act as protease enhancers in this setting, revealing newly identified Scube2 functions in Hh signaling regulation.

  3. Preparation and surface characterization of HMDI-activated 316L stainless steel for coronary artery stents.

    PubMed

    Chuang, T-W; Chen, M-H; Lin, F-H

    2008-06-01

    Poor compatibility between blood and metallic coronary artery stents is one reason for arterial restenosis. Immobilization of anticoagulant agents on the stent's surface is feasible for improving compatibility. We examined possible surface-coupling agents for anticoagulant agent immobilization. Hexamethylene diisocyanate (HMDI) and 3-aminopropyl-triethoxysilane (APTS) were examined as surface-coupling agents to activate 316L stainless steel (e.g., stent material). The activated surface was characterized using Fourier transformation infrared spectroscopy (FTIR), atomic force microscope (AFM), surface plasmon resonance (SPR), and trinitrobenzene sulfonic acid (TNBS) assay. In FTIR analysis, HMDI and APTS were both covalently linked to 316L stainless steel. In AFM analysis, it was found that the HMDI-activated surface was smoother than the APTS-activated one. In SPR test, the shift of SPR angle for the APTS-activated surface was much higher than that for the HMDI-activated surface after being challenged with acidic solution. TNBS assay was used to determine the amount of immobilized primary amine groups. The HMDI-activated surface was found to consist of about 1.32 micromol/cm(2) amine group, whereas the APTS-activated surface consisted of only 0.89 micromol/cm(2) amine group. We conclude that the HMDI-activated surface has more desirable surface characteristics than the APTS-activated surface has, such as chemical stability and the amount of active amine groups.

  4. Tectonics and surface processes interactions in exhumation history of South Alaska: insights from the thermochronological record

    NASA Astrophysics Data System (ADS)

    Valla, Pierre G.; Champagnac, Jean-Daniel; Shuster, David L.; Herman, Frederic; Giuditta Fellin, Maria

    2014-05-01

    The southern Alaska range presents an ideal setting to study complex interactions between tectonics, climate and surface processes in landscape evolution. It exhibits active tectonics with the ongoing of subduction/collision between Pacific and North America, and major active seismogenic reverse and strike-slip faults. The alpine landscape, rugged topography and the important present-day ice-coverage reveal a strong glacial imprint associated with high erosion and sediment transport rates. Therefore, the relative importance of glacial erosion and tectonics for the observed late-exhumation history appears to be quite complex to decipher. This problem partly arises from the fact that most studies have been focused on the southern coast of Alaska where both glacial erosion and tectonic processes are both very active and act together in driving high exhumation rates. Here, we first perform a formal inversion of an extensive bedrock thermochronological dataset collected in southern Alaska over the last decades to quantify the large-scale 20-Myr exhumation history. Our results confirm high exhumation rates in the St Elias "syntaxis" and frontal fold and thrust belts for the last 0-2 Myr, where major ice fields and high precipitation rates likely promoted high erosion rates. It also highlights localized exhumation in the last 4-6 Myr along major tectonic features such like the Fairweather and Border Ranges faults. Large-scale inverse modeling therefore suggests that the late-stage exhumation history of South Alaska has mainly been driven by tectonic processes; the impact of late Cenozoic glaciations impact being less visible there than in less active mountain ranges such as the European Alps, British Columbia or Patagonia. To overcome this potential bias in resolving the glacial impact on erosion history, we studied to the Granite Range (Wrangell-St Elias National Park, Alaska), an area presenting a strong glacial imprint but minor tectonic activity with only localized

  5. The process development of laser surface modification of commercially pure titanium (Grade 2) with rhenium

    NASA Astrophysics Data System (ADS)

    Kobiela, K.; Smolina, I.; Dziedzic, R.; Szymczyk, P.; Kurzynowski, T.; Chlebus, E.

    2016-12-01

    The paper presents the results of the process development of laser surface modification of commercially pure titanium with rhenium. The criterion of the successful/optimal process is the repetitive geometry of the surface, characterized by predictable and repetitive chemical composition over its entire surface as well as special mechanical properties (hardness and wear resistance). The analysis of surface geometry concluded measurements of laser penetration depth and heat affected zone (HAZ), the width of a single track as well as width of a clad. The diode laser installed on the industrial robot carried out the laser treatment. This solution made possible the continuous supply of powder to the substrate during the process. The aim of an investigation is find out the possibility of improving the tribological characteristics of the surface due to the rhenium alloying. The verification of the surface properties (tribological) concluded geometry measurements, microstructure observation, hardness tests and evaluation of wear resistance.

  6. Nature of Catalytic Active Sites Present on the Surface of Advanced Bulk Tantalum Mixed Oxide Photocatalysts

    SciTech Connect

    Phivilay, Somphonh; Puretzky, Alexander A; Domen, Kazunari Domen; Wachs, Israel

    2013-01-01

    The most active photocatalyst system for water splitting under UV irradiation (270 nm) is the promoted 0.2%NiO/NaTaO3:2%La photocatalyst with optimized photonic efficiency (P.E.) of 56%, but fundamental issues about the nature of the surface catalytic active sites and their involvement in the photocatalytic process still need to be clarified. This is the first study to apply cutting edge surface spectroscopic analyses to determine the surface nature of tantalum mixed oxide photocatalysts. Surface analysis with HR-XPS (1-3nm) and HS-LEIS (0.3nm) spectroscopy indicates that the NiO and La2O3 promoters are concentrated in the surface region of the bulk NaTaO3 phase. The La2O3 is concentrated on the NaTaO3 outermost surface layers while NiO is distributed throughout the NaTaO3 surface region (1-3nm). Raman and UV-vis spectroscopy revealed that the bulk molecular and electronic structures, respectively, of NaTaO3 were not modified by the addition of the La2O3 and NiO promoters, with La2O3 resulting in a slightly more ordered structure. Photoluminescence (PL) spectroscopy reveals that the addition of La2O3 and NiO produces a greater number of electron traps resulting in the suppression of the recombination of excited electrons/holes. In contrast to earlier reports, the La2O3 is only a textural promoter (increasing the BET surface area ~7x by stabilizing smaller NaTaO3 particles), but causes a ~3x decrease in the specific photocatalytic TORs ( mol H2/m2/h) rate because surface La2O3 blocks exposed catalytic active NaTaO3 sites. The NiO promoter was found to be a potent electronic promoter that enhances the NaTaO3 surface normalized TORs by a factor of ~10-50 and TOF by a factor of ~10. The level of NiO promotion is the same in the absence and presence of La2O3 demonstrating that there is no promotional synergistic interaction between the NiO and La2O3 promoters. This study demonstrates the important contributions of the photocatalyst surface properties to the fundamental

  7. Behavior, activities, and effects of bacteria on synthetic quartz monocrystal surfaces.

    PubMed

    Rades-Rohkohl, E; Fränzle, O; Hirsch, P

    1977-09-01

    Two strains ofBacillus sp. and a strain ofBrevibacterium sp., originally isolated from a natural quartzite surface, were characterized and employed as test strains with several methods: acridine orange fluorochromation and epifluorescence microscopy were used for detection of individual cells; scanning and transmission microscopy for studying attachment behavior; replica techniques in combination with electron microscopy for following surface interaction effects; and chemical analysis of SiO2 for detecting possible silica leaching activities. The experimental results clearly showed that the three test strains were able to attach to and grow on the precleaned quartz surfaces. Attachment modes were either by direct sorption mechanisms (Brevibacterium sp. S) or the production of adhesive polymers (Bacillus sp. U andBacillus sp. W). In short-term contact incubation experiments with rich media, neither quartz crystal surface structures nor bacterial cell surfaces appeared to be changed. Likewise, significant biochemical dissolution and mechanical dislocation of SiO2 (which would have indicated rapid bacterial weathering activities) could not be detected. The importance of quartz purity and crystalline structure for the initiation of weathering processes is discussed.

  8. Synthesis, surface properties and antimicrobial activity of some germanium nonionic surfactants.

    PubMed

    Zaki, Mohamed F; Tawfik, Salah M

    2014-01-01

    Esterification reaction between different fatty acid namely; lauric, stearic, oleic and linoleic acids and polyethylene glycol-400 were performed. The produced polyethylene glycol ester were reacted with p-amine benzoic acid followed by condensation reaction with germanium dioxide in presence of sodium carbonate to form desired germinate surfactants. The chemical structures of the synthesized surfactants were determined using different spectra tools. The surface parameter including: the critical micelle concentration (CMC), effectiveness (π(cmc)), efficiency (Pc20), maximum surface excess (Γ(max)) and minimum surface area (A(min)), were calculated from the surface tension measurements. The synthesized surfactants showed higher surface activity. The thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the synthesized nonionic surfactants showed their tendency towards adsorption at the interfaces and also micellization in the bulk of their solutions. The synthesized surfactants were tested against different strain of bacteria using inhibition zone diameters. The synthesized surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative as well as fungi. The promising inhibition efficiency of these compounds against the sulfate reducing bacteria facilitates them to be applicable as new categories of sulfate reducing bacteria biocides.

  9. Managing complexity in simulations of land surface and near-surface processes

    SciTech Connect

    Coon, Ethan T.; Moulton, J. David; Painter, Scott L.

    2016-01-12

    Increasing computing power and the growing role of simulation in Earth systems science have led to an increase in the number and complexity of processes in modern simulators. We present a multiphysics framework that specifies interfaces for coupled processes and automates weak and strong coupling strategies to manage this complexity. Process management is enabled by viewing the system of equations as a tree, where individual equations are associated with leaf nodes and coupling strategies with internal nodes. A dynamically generated dependency graph connects a variable to its dependencies, streamlining and automating model evaluation, easing model development, and ensuring models are modular and flexible. Additionally, the dependency graph is used to ensure that data requirements are consistent between all processes in a given simulation. Here we discuss the design and implementation of these concepts within the Arcos framework, and demonstrate their use for verification testing and hypothesis evaluation in numerical experiments.

  10. Managing complexity in simulations of land surface and near-surface processes

    DOE PAGES

    Coon, Ethan T.; Moulton, J. David; Painter, Scott L.

    2016-01-12

    Increasing computing power and the growing role of simulation in Earth systems science have led to an increase in the number and complexity of processes in modern simulators. We present a multiphysics framework that specifies interfaces for coupled processes and automates weak and strong coupling strategies to manage this complexity. Process management is enabled by viewing the system of equations as a tree, where individual equations are associated with leaf nodes and coupling strategies with internal nodes. A dynamically generated dependency graph connects a variable to its dependencies, streamlining and automating model evaluation, easing model development, and ensuring models aremore » modular and flexible. Additionally, the dependency graph is used to ensure that data requirements are consistent between all processes in a given simulation. Here we discuss the design and implementation of these concepts within the Arcos framework, and demonstrate their use for verification testing and hypothesis evaluation in numerical experiments.« less

  11. Innate immunity activation on biomaterial surfaces: A mechanistic model and coping strategies

    PubMed Central

    Ekdahl, Kristina N; Lambris, John D.; Elwing, Hans; Ricklin, Daniel; Nilsson, Per H.; Teramura, Yuji; Nicholls, Ian A.; Nilsson, Bo

    2011-01-01

    When an artificial biomaterial (e.g., a stent or implantable pump) is exposed to blood, plasma proteins immediately adhere to the surface, creating a new interface between the biomaterial and the blood. The recognition proteins within the complement and contact activation/coagulation cascade systems of the blood will be bound to, or inserted into, this protein film and generate different mediators that will activate polymorphonuclear leukocytes and monocytes, as well as platelets. Under clinical conditions, the ultimate outcome of these processes may be thrombotic and inflammatory reactions, and consequently the composition and conformation of the proteins in the initial layer formed on the surface will to a large extent determine the outcome of a treatment involving the biomaterial, affecting both the functionality of the material and the patient’s life quality. This review presents models of biomaterial-induced activation processes and describes various strategies to attenuate potential adverse reactions by conjugating bioactive molecules to surfaces or by introducing nanostructures. PMID:21771620

  12. Cascading Activation across Levels of Representation in Children's Lexical Processing

    ERIC Educational Resources Information Center

    Huang, Yi Ting; Snedeker, Jesse

    2011-01-01

    Recent work in adult psycholinguistics has demonstrated that activation of semantic representations begins long before phonological processing is complete. This incremental propagation of information across multiple levels of analysis is a hallmark of adult language processing but how does this ability develop? In two experiments, we elicit…

  13. Instructional Transaction Theory: Knowledge Relationships among Processes, Entities, and Activities.

    ERIC Educational Resources Information Center

    Merrill, M. David; And Others

    1993-01-01

    Discussion of instructional transaction theory focuses on knowledge representation in an automated instructional design expert system. A knowledge structure called PEA-Net (processes, entities, and activities) is explained; the refrigeration process is used as an example; text resources and graphic resources are described; and simulations are…

  14. Students' Learning Activities While Studying Biological Process Diagrams

    ERIC Educational Resources Information Center

    Kragten, Marco; Admiraal, Wilfried; Rijlaarsdam, Gert

    2015-01-01

    Process diagrams describe how a system functions (e.g. photosynthesis) and are an important type of representation in Biology education. In the present study, we examined students' learning activities while studying process diagrams, related to their resulting comprehension of these diagrams. Each student completed three learning tasks. Verbal…

  15. Influence of Surface Seawater and Atmospheric Conditions on the Ccn Activity of Ocean-Derived Aerosol

    NASA Astrophysics Data System (ADS)

    Quinn, P.; Bates, T. S.; Russell, L. M.; Frossard, A. A.; Keene, W. C.; Kieber, D. J.; Hakala, J. P.

    2012-12-01

    Ocean-derived aerosols are produced from direct injection into the atmosphere (primary production) and gas-to-particle conversion in the atmosphere (secondary production). These different production mechanisms result in a broad range of particle sizes that has implications for the impact of ocean-derived aerosol on climate. The chemical composition of ocean-derived aerosols is a result of a complex mixture of inorganic sea salt and organic matter including polysaccharides, proteins, amino acids, microorganisms and their fragments, and secondary oxidation products. Both production mechanisms and biological processes in the surface ocean impact the ability of ocean-derived aerosol to act as cloud condensation nuclei (CCN). In addition, CCN activity can be impacted by atmospheric processing that modifies particle size and composition after the aerosol is emitted from the ocean. To understand relationships between production mechanism, surface ocean biology, and atmospheric processing, measurements were made of surface ocean chlorophyll and dissolved organic matter; nascent sea spray aerosol freshly emitted from the ocean surface; and ambient marine aerosol. These measurements were made along the coast of California and in the North Atlantic between the northeast US and Bermuda. These regions include both eutrophic and oligotraphic waters and, thus, provide for observations over a wide range of ocean conditions.

  16. Research on large aperture multi-angle multi-surface mirror process technology

    NASA Astrophysics Data System (ADS)

    Huang, Ying; He, Manze; Yan, Dingyao; Liu, Yibin

    2016-10-01

    Light weighted multi-angle multi-surface mirror is made of glass-ceramic, with the structural characteristic of multicavity thin wall, high precision of surface figure and angle between surfaces, has very different processing technology with traditional solid mirror. Based on the 460mm×434mm×80mm multi-angle multi-surface mirror, glass combination manufacture method and relevant interferometry of angle measurement was designed. The process technology was studied, then the consistency of angle between surfaces and the influence on multi-cavity thin wall deformation of lateral surface and material of polishing pad on the surface figure processing were controlled. The model between the variation of angle and load was established, from which the hysteresis of angle variation was analyzed, then the prototype workpiece was finished. The difficult problem on synchronically controlling the surface angles and surface figure of the mirror, which has high center of gravity and multi-cavity thin wall, was solved. The lateral surface figure was controlled below λ/6 (PV, λ=632.8nm), and the perpendicularity of lateral surfaces were controlled below 5''.

  17. Enhanced Multistatic Active Sonar via Innovative Signal Processing

    DTIC Science & Technology

    2014-09-30

    DATES COVERED (From - To) Oct. 01. 2013-Sept. 30, 2014 4. TITLE AND SUBTITLE Enhanced Multistatic Active Sonar via Innovative Signal Processing 5a...DISTRIBUTION AVAILABILITY STATEMENT Approved for Public Release; Distribution is Unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT Pulsed active sonar ...PAS) and continuous active sonar (CAS) in the presence of strong direct blast are studied for the Doppler-tolerant linear frequency modulation

  18. Surface modification by electrolytic plasma processing for high Nb-TiAl alloys

    NASA Astrophysics Data System (ADS)

    Gui, Wanyuan; Hao, Guojian; Liang, Yongfeng; Li, Feng; Liu, Xiao; Lin, Junpin

    2016-12-01

    Metal surface modification by electrolytic plasma processing (EPP) is an innovative treatment widely commonly applied to material processing and pretreatment process of coating and galvanization. EPP involves complex processes and a great deal of parameters, such as preset voltage, current, solution temperature and processing time. Several characterization methods are presented in this paper for evaluating the micro-structure surfaces of Ti45Al8Nb alloys: SEM, EDS, XRD and 3D topography. The results showed that the oxide scale and other contaminants on the surface of Ti45Al8Nb alloys can be effectively removed via EPP. The typical micro-crater structure of the surface of Ti45Al8Nb alloys were observed by 3D topography after EPP to find that the mean diameter of the surface structure and roughness value can be effectively controlled by altering the processing parameters. The mechanical properties of the surface according to nanomechanical probe testing exhibited slight decrease in microhardness and elastic modulus after EPP, but a dramatic increase in surface roughness, which is beneficial for further processing or coating.

  19. Surface Modified Particles By Multi-Step Addition And Process For The Preparation Thereof

    DOEpatents

    Cook, Ronald Lee; Elliott, Brian John; Luebben, Silvia DeVito; Myers, Andrew William; Smith, Bryan Matthew

    2006-01-17

    The present invention relates to a new class of surface modified particles and to a multi-step surface modification process for the preparation of the same. The multi-step surface functionalization process involves two or more reactions to produce particles that are compatible with various host systems and/or to provide the particles with particular chemical reactivities. The initial step comprises the attachment of a small organic compound to the surface of the inorganic particle. The subsequent steps attach additional compounds to the previously attached organic compounds through organic linking groups.

  20. Superhydrophobic aluminum alloy surfaces by a novel one-step process.

    PubMed

    Saleema, N; Sarkar, D K; Paynter, R W; Chen, X-G

    2010-09-01

    A simple one-step process has been developed to render aluminum alloy surfaces superhydrophobic by immersing the aluminum alloy substrates in a solution containing NaOH and fluoroalkyl-silane (FAS-17) molecules. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements have been performed to characterize the morphological features, chemical composition and superhydrophobicity of the surfaces. The resulting surfaces provided a water contact angle as high as ∼162° and a contact angle hysteresis as low as ∼4°. The study indicates that it is possible to fabricate superhydrophobic aluminum surfaces easily and effectively without involving the traditional two-step processes.

  1. Revisiting the correlation between stellar activity and planetary surface gravity

    NASA Astrophysics Data System (ADS)

    Figueira, P.; Oshagh, M.; Adibekyan, V. Zh.; Santos, N. C.

    2014-12-01

    Aims: We re-evaluate the correlation between planetary surface gravity and stellar host activity as measured by the index log (R'HK). This correlation, previously identified by Hartman (2010, ApJ, 717, L138), is now analyzed in light of an extended measurement dataset, roughly three times larger than the original one. Methods: We calculated the Spearman rank correlation coefficient between the two quantities and its associated p-value. The correlation coefficient was calculated for both the full dataset and the star-planet pairs that follow the conditions proposed by Hartman (2010). To do so, we considered effective temperatures both as collected from the literature and from the SWEET-Cat catalog, which provides a more homogeneous and accurate effective temperature determination. Results: The analysis delivers significant correlation coefficients, but with a lower value than those obtained by Hartman (2010). The two datasets are compatible, and we show that a correlation coefficient as high as previously published can arise naturally from a small-number statistics analysis of the current dataset. The correlation is recovered for star-planet pairs selected using the different conditions proposed by Hartman (2010). Remarkably, the usage of SWEET-Cat temperatures led to higher correlation coefficient values. We highlight and discuss the role of the correlation betwen different parameters such as effective temperature and activity index. Several additional effects on top of those discussed previously were considered, but none fully explains the detected correlation. In light of the complex issue discussed here, we encourage the different follow-up teams to publish their activity index values in the form of a log (R'HK) index so that a comparison across stars and instruments can be pursued. Appendix A is available in electronic form at http://www.aanda.org

  2. Controlled Release of Biologically Active Silver from Nanosilver Surfaces

    PubMed Central

    Liu, Jingyu; Sonshine, David A.; Shervani, Saira; Hurt, Robert H.

    2010-01-01

    Major pathways in the antibacterial activity and eukaryotic toxicity of nano-silver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nano-silver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nano-silver is widely recognized, the drug delivery paradigm has not been well developed for this system, and there is significant potential to improve nano-silver technologies through controlled release formulations. This article applies elements of the drug delivery paradigm to nano-silver dissolution and presents a systematic study of chemical concepts for controlled release. After presenting thermodynamic calculations of silver species partitioning in biological media, the rates of oxidative silver dissolution are measured for nanoparticles and macroscopic foils and used to derive unified area-based release kinetics. A variety of competing chemical approaches are demonstrated for controlling the ion release rate over four orders of magnitude. Release can be systematically slowed by thiol and citrate ligand binding, formation of sulfidic coatings, or the scavenging of peroxy-intermediates. Release can be accelerated by pre-oxidation or particle size reduction, while polymer coatings with complexation sites alter the release profile by storing and release inventories of surface-bound silver. Finally, the ability to tune biological activity is demonstrated through bacterial inhibition zone assay carried out on selected formulations of controlled release nano-silver. PMID:20968290

  3. DIVERGENT HORIZONTAL SUB-SURFACE FLOWS WITHIN ACTIVE REGION 11158

    SciTech Connect

    Jain, Kiran; Tripathy, S. C.; Hill, F. E-mail: stripathy@nso.edu

    2015-07-20

    We measure the horizontal subsurface flow in a fast emerging active region (AR; NOAA 11158) using the ring-diagram technique and the Helioseismic and Magnetic Imager high spatial resolution Dopplergrams. This AR had a complex magnetic structure and displayed significant changes in morphology during its disk passage. Over a period of six days from 2011 February 11 to 16, the temporal variation in the magnitude of the total velocity is found to follow the trend of magnetic field strength. We further analyze regions of individual magnetic polarity within AR 11158 and find that the horizontal velocity components in these sub-regions have significant variation with time and depth. The leading and trailing polarity regions move faster than the mixed-polarity region. Furthermore, both zonal and meridional components have opposite signs for trailing and leading polarity regions at all depths showing divergent flows within the AR. We also find a sharp decrease in the magnitude of total horizontal velocity in deeper layers around major flares. It is suggested that the re-organization of magnetic fields during flares, combined with the sunspot rotation, decreases the magnitude of horizontal flows or that the flow kinetic energy has been converted into the energy released by flares. After the decline in flare activity and sunspot rotation, the flows tend to follow the pattern of magnetic activity. We also observe less variation in the velocity components near the surface but these tend to increase with depth, further demonstrating that the deeper layers are more affected by the topology of ARs.

  4. Dissecting gamma frequency activity during human memory processing.

    PubMed

    Kucewicz, Michal T; Berry, Brent M; Kremen, Vaclav; Brinkmann, Benjamin H; Sperling, Michael R; Jobst, Barbara C; Gross, Robert E; Lega, Bradley; Sheth, Sameer A; Stein, Joel M; Das, Sandthitsu R; Gorniak, Richard; Stead, S Matthew; Rizzuto, Daniel S; Kahana, Michael J; Worrell, Gregory A

    2017-03-13

    Gamma frequency activity (30-150 Hz) is induced in cognitive tasks and is thought to reflect underlying neural processes. Gamma frequency activity can be recorded directly from the human brain using intracranial electrodes implanted in patients undergoing treatment for drug-resistant epilepsy. Previous studies have independently explored narrowband oscillations in the local field potential and broadband power increases. It is not clear, however, which processes contribute to human brain gamma frequency activity, or their dynamics and roles during memory processing. Here a large dataset of intracranial recordings obtained during encoding of words from 101 patients was used to detect, characterize and compare induced gamma frequency activity events. Individual bursts of gamma frequency activity were isolated in the time-frequency domain to determine their spectral features, including peak frequency, amplitude, frequency span, and duration. We found two distinct types of gamma frequency activity events that showed either narrowband or broadband frequency spans revealing characteristic spectral properties. Narrowband events, the predominant type, were induced by word presentations following an initial induction of broadband events, which were temporally separated and selectively correlated with evoked response potentials, suggesting that they reflect different neural activities and play different roles during memory encoding. The two gamma frequency activity types were differentially modulated during encoding of subsequently recalled and forgotten words. In conclusion, we found evidence for two distinct activity types induced in the gamma frequency range during cognitive processing. Separating these two gamma frequency activity components contributes to the current understanding of electrophysiological biomarkers, and may prove useful for emerging neurotechnologies targeting, mapping and modulating distinct neurophysiological processes in normal and epileptogenic brain.

  5. Modeling and optimization of red currants vacuum drying process by response surface methodology (RSM).

    PubMed

    Šumić, Zdravko; Vakula, Anita; Tepić, Aleksandra; Čakarević, Jelena; Vitas, Jasmina; Pavlić, Branimir

    2016-07-15

    Fresh red currants were dried by vacuum drying process under different drying conditions. Box-Behnken experimental design with response surface methodology was used for optimization of drying process in terms of physical (moisture content, water activity, total color change, firmness and rehydratation power) and chemical (total phenols, total flavonoids, monomeric anthocyanins and ascorbic acid content and antioxidant activity) properties of dried samples. Temperature (48-78 °C), pressure (30-330 mbar) and drying time (8-16 h) were investigated as independent variables. Experimental results were fitted to a second-order polynomial model where regression analysis and analysis of variance were used to determine model fitness and optimal drying conditions. The optimal conditions of simultaneously optimized responses were temperature of 70.2 °C, pressure of 39 mbar and drying time of 8 h. It could be concluded that vacuum drying provides samples with good physico-chemical properties, similar to lyophilized sample and better than conventionally dried sample.

  6. Investigation of oxidation process of mechanically activated ultrafine iron powders

    NASA Astrophysics Data System (ADS)

    Lysenko, E. N.; Nikolaev, E. V.; Vlasov, V. A.; Zhuravkov, S. P.

    2016-02-01

    The oxidation of mechanically activated ultrafine iron powders was studied using X- ray powder diffraction and thermogravimetric analyzes. The powders with average particles size of 100 nm were made by the electric explosion of wire, and were subjected to mechanical activation in planetary ball mill for 15 and 40 minutes. It was shown that a certain amount of FeO phase is formed during mechanical activation of ultrafine iron powders. According to thermogravimetric analysis, the oxidation process of non-milled ultrafine iron powders is a complex process and occurs in three stages. The preliminary mechanical activation of powders considerably changes the nature of the iron powders oxidation, leads to increasing in the temperature of oxidation onset and shifts the reaction to higher temperatures. For the milled powders, the oxidation is more simple process and occurs in a single step.

  7. Two-dimensional quantification of the corrosion process in metal surfaces using digital speckle pattern interferometry

    SciTech Connect

    Andres, N.; Lobera, J.; Arroyo, M. P.; Angurel, L. A.

    2011-04-01

    The applicability of digital speckle pattern interferometry (DSPI) to the analysis of surface corrosion processes has been evaluated by studying the evolution of an Fe surface immersed in sulfuric acid. This work describes the analysis process required to obtain quantitative information about the corrosion process. It has been possible to evaluate the corrosion rate, and the results agree with those derived from the weight loss method. In addition, a two-dimensional analysis has been applied, showing that DSPI measurements can be used to extract information about the corrosion rate at any region of the surface.

  8. C-H Activation on Co,O Sites: Isolated Surface Sites versus Molecular Analogs.

    PubMed

    Estes, Deven P; Siddiqi, Georges; Allouche, Florian; Kovtunov, Kirill V; Safonova, Olga V; Trigub, Alexander L; Koptyug, Igor V; Copéret, Christophe

    2016-11-16

    The activation and conversion of hydrocarbons is one of the most important challenges in chemistry. Transition-metal ions (V, Cr, Fe, Co, etc.) isolated on silica surfaces are known to catalyze such processes. The mechanisms of these processes are currently unknown but are thought to involve C-H activation as the rate-determining step. Here, we synthesize well-defined Co(II) ions on a silica surface using a metal siloxide precursor followed by thermal treatment under vacuum at 500 °C. We show that these isolated Co(II) sites are catalysts for a number of hydrocarbon conversion reactions, such as the dehydrogenation of propane, the hydrogenation of propene, and the trimerization of terminal alkynes. We then investigate the mechanisms of these processes using kinetics, kinetic isotope effects, isotopic labeling experiments, parahydrogen induced polarization (PHIP) NMR, and comparison with a molecular analog. The data are consistent with all of these reactions occurring by a common mechanism, involving heterolytic C-H or H-H activation via a 1,2 addition across a Co-O bond.

  9. Measurement of surface mercury fluxes at active industrial gold mines in Nevada (USA).

    PubMed

    Eckley, C S; Gustin, M; Marsik, F; Miller, M B

    2011-01-01

    Mercury (Hg) may be naturally associated with the rock units hosting precious and base metal deposits. Active gold mines are known to have point source releases of Hg associated with ore processing facilities. The nonpoint source release of Hg to the air from the large area (hundreds to thousands of hectares) of disturbed and processed material at industrial open pit gold mines has not been quantified. This paper describes the field data collected as part of a project focused on estimating nonpoint source emissions of Hg from two active mines in Nevada, USA. In situ Hg flux data were collected on diel and seasonal time steps using a dynamic flux chamber from representative mine surfaces. Hg fluxes ranged from <1500 ng m(-2) day(-1) for waste rock piles (0.6-3.5 μg g(-1)) to 684,000 ng m(-2) day(-1) for tailings (2.8-58 μg g(-1)). Releases were positively correlated with material Hg concentrations, surface grain size, and moisture content. Highest Hg releases occurred from materials under active cyanide leaching and from tailings impoundments containing processed high-grade ore. Data collected indicate that as mine sites are reclaimed and material disturbance ceases, emissions will decline. Additionally local cycling of atmospheric Hg (deposition and re-emission) was found to occur.

  10. Energy storage on ultrahigh surface area activated carbon fibers derived from PMIA.

    PubMed

    Castro-Muñiz, Alberto; Suárez-García, Fabián; Martínez-Alonso, Amelia; Tascón, Juan M D; Kyotani, Takashi

    2013-08-01

    High-performance carbon materials for energy storage applications have been obtained by using poly(m-phenylene isophthalamide), PMIA, as a precursor through the chemical activation of the carbonized aramid fiber by using KOH. The yield of the process of activation was remarkably high (25-40 wt%), resulting in activated carbon fibers (ACFs) with ultrahigh surface areas, over 3000 m(2) g(-1) , and pore volumes exceeding 1.50 cm(3) g(-1) , keeping intact the fibrous morphology. The porous structure and the surface chemical properties could easily be controlled through the conditions of activation. The PMIA-derived ACFs were tested in two types of energy storage applications. At -196 °C and 1 bar, H2 uptake values of approximately 3 t% were obtained, which, in combination with the textural properties, rendered it a good candidate for H2 adsorption at high pressure and temperature. The performance of the ACFs as electrodes for electrochemical supercapacitors was also investigated. Specific capacitance values between 297 and 531 g(-1) at 50 mA g(-1) were obtained in aqueous electrolyte (1 H2 SO4 ), showing different behaviors depending on the surface chemical properties.

  11. [Preparation and optimum process of walnut peel activated carbon by zinc chloride as activating agent].

    PubMed

    Liu, Xiao-hong; Wang, Xing-wei; Zhao, Bo; Lü, Jun-fang; Kang, Ni-na; Zhang, Yao-jun

    2014-12-01

    Walnut peel as raw material, zinc chloride was used as activating agent for preparation walnut peel activated carbon in the muffle furnace in this experiment, using orthogonal design. Yield, the specific surface area and iodine number of walnut peel activated carbon were determined at all designed experimental conditions and the optimum technological condition of preparation was obtained. By analysis of aperture, infrared spectra and the content of acidic group in surface with Boehm, walnut peel activated carbon of prepared at the optimum condition was characterized. The results showed the optimum technological parameters of preparation: activation temperature (600 °C), activation time (1 h), the concentration of zinc chloride (50%), the particle size (60 mesh). The specific surface area of walnut peel activated carbon obtained at optimum condition was mounting to 1258.05 m2 · g(-1), the ratio of medium porous 32.18%. Therefore, walnut peel can be used in the preparation of the high-quality activated carbon of large surface area. Agricultural wastes, as walnut peel, not only were implemented recycle, but also didn't make any pollution. Meanwhile, a cheap adsorbent was provided and it was of great significance to open a new source of activated carbon.

  12. Surface and Interface Engineering of Noble-Metal-Free Electrocatalysts for Efficient Energy Conversion Processes.

    PubMed

    Zhu, Yun Pei; Guo, Chunxian; Zheng, Yao; Qiao, Shi-Zhang

    2017-02-16

    . Although the majority of carbon-based materials remain uncompetitive with state-of-the-art metal-based catalysts for the aforementioned catalytic processes, non-metal carbon hybrids have already shown performance that typically only conventional noble metals or transition metal materials can achieve. The idea of hybridized carbon-based catalysts possessing unique active surfaces and macro- or nanostructures is addressed herein. For metal-carbon couples, the incorporation of carbon can effectively compensate for the intrinsic deficiency in conductivity of the metallic components. Chemical modification of carbon frameworks, such as nitrogen doping, not only can change the electron-donor character, but also can introduce anchoring sites for immobilizing active metallic centers to form metal-nitrogen-carbon (M-N-C) species, which are thought to facilitate the electrocatalytic process. With thoughtful material design, control over the porosity of composites, the molecular architecture of active metal moieties and macromorphologies of the whole catalysts can be achieved, leading to a better understanding structure-activity relationships. We hope that we can offer new insight into material design, particularly the role of chemical composition and structural properties in electrochemical performance and reaction mechanisms.

  13. A surface-associated activity trap for capturing water surface and aquatic invertebrates in wetlands

    USGS Publications Warehouse

    Hanson, Mark A.; Roy, Christiane C.; Euliss, Ned H.; Zimmer, Kyle D.; Riggs, Michael R.; Butler, Malcolm G.

    2000-01-01

    We developed a surface-associated activity trap (SAT) for sampling aquatic invertebrates in wetlands. We compared performance of this trap with that of a conventional activity trap (AT) based on non-detection rates and relative abundance estimates for 13 taxa of common wetland invertebrates and for taxon richness using data from experiments in constructed wetlands. Taxon-specific non-detection rates for ATs generally exceeded those of SATs, and largest improvements using SATs were for Chironomidae and Gastropoda. SATs were efficient at capturing cladocera, Chironomidae, Gastropoda, total Crustacea, and multiple taxa (taxon richness) but were only slightly better than ATs at capturing Dytiscidae. Temporal differences in capture rates were observed only for cladocera, Chironomidae, Dytiscidae, and total Crustacea, with capture efficiencies of SATs usually decreasing from mid-June through mid-July for these taxa. We believe that SATs may be useful for characterizing wetland invertebrate communities and for developing improved measures of prey available to foraging waterfowl and other aquatic birds.

  14. A surface-associated activity trap for capturing water-surface and aquatic invertebrates in wetlands

    USGS Publications Warehouse

    Hanson, M.A.; Roy, C.C.; Euliss, N.H.; Zimmer, K.D.; Riggs, M.R.; Butler, Malcolm G.

    2000-01-01

    We developed a surface-associated activity trap (SAT) for sampling aquatic invertebrates in wetlands. We compared performance of this trap with that of a conventional activity trap (AT) based on non-detection rates and relative abundance estimates for 13 taxa of common wetland invertebrates and for taxon richness using data from experiments in constructed wetlands. Taxon-specific non-detection rates for ATs generally exceeded those of SATs, and largest improvements using SATs were for Chironomidae and Gastropoda. SATs were efficient at capturing cladocera, Chironomidae, Gastropoda, total Crustacea, and multiple taxa (taxon richness) but were only slightly better than ATs at capturing Dytiscidae. Temporal differences in capture rates were observed only for cladocera, Chironomidae, Dytiscidae, and total Crustacea, with capture efficiencies of SATs usually decreasing from mid-June through mid-July for these taxa. We believe that SATs may be useful for characterizing wetland invertebrate communities and for developing improved measures of prey available to foraging waterfowl and other aquatic birds.

  15. Digital image processing and analysis for activated sludge wastewater treatment.

    PubMed

    Khan, Muhammad Burhan; Lee, Xue Yong; Nisar, Humaira; Ng, Choon Aun; Yeap, Kim Ho; Malik, Aamir Saeed

    2015-01-01

    Activated sludge system is generally used in wastewater treatment plants for processing domestic influent. Conventionally the activated sludge wastewater treatment is monitored by measuring physico-chemical parameters like total suspended solids (TSSol), sludge volume index (SVI) and chemical oxygen demand (COD) etc. For the measurement, tests are conducted in the laboratory, which take many hours to give the final measurement. Digital image processing and analysis offers a better alternative not only to monitor and characterize the current state of activated sludge but also to predict the future state. The characterization by image processing and analysis is done by correlating the time evolution of parameters extracted by image analysis of floc and filaments with the physico-chemical parameters. This chapter briefly reviews the activated sludge wastewater treatment; and, procedures of image acquisition, preprocessing, segmentation and analysis in the specific context of activated sludge wastewater treatment. In the latter part additional procedures like z-stacking, image stitching are introduced for wastewater image preprocessing, which are not previously used in the context of activated sludge. Different preprocessing and segmentation techniques are proposed, along with the survey of imaging procedures reported in the literature. Finally the image analysis based morphological parameters and correlation of the parameters with regard to monitoring and prediction of activated sludge are discussed. Hence it is observed that image analysis can play a very useful role in the monitoring of activated sludge wastewater treatment plants.

  16. Ab initio trajectory surface-hopping study on ultrafast deactivation process of thiophene.

    PubMed

    Cui, Ganglong; Fang, Weihai

    2011-10-27

    The ultrafast S(1)((1)ππ*) → S(0) deactivation process of thiophene in the gas phase has been simulated with the complete active space self-consistent field (CASSCF) based fewest switch surface hopping method. It was found that most of the calculated trajectories (∼80%) decay to the ground state (S(0)) with an averaged time constant of 65 ± 5 fs. This is in good agreement with the experimental value of about 80 fs. Two conical intersections were determined to be responsible for the ultrafast S(1)((1)ππ*) → S(0) internal conversion process. After thiophene is excited to the S(1)((1)ππ*) state in the Franck-Condon region, it quickly relaxes to the minimum of the S(1)((1)ππ*) state, then overcomes a small barrier near the conical intersection (CI((1)ππ*/(1)πσ*)), and eventually arrives at the minimum of one C-S bond fission (S(1)((1)πσ*)). In the vicinity of this minimum, the conical intersection (CI((1)πσ*/S(0))) funnels the electron population to the ground state (S(0)), completing the ultrafast S(1)((1)ππ*) → S(0) internal conversion process. This decay mechanism matches well with previous experimental and theoretical studies.

  17. A process for SOI resonators with surface micromachined covers and reduced electrostatic gaps

    NASA Astrophysics Data System (ADS)

    Dekker, James R.; Alastalo, Ari; Kattelus, Hannu

    2010-04-01

    This paper describes work to fabricate resonators on silicon-on-insulator (SOI) wafers with sub-micron gaps and wafer level encapsulation. Non-aligned, high-temperature fusion bonding of a cover wafer over unreleased structures etched into a SOI wafer is followed by cover wafer stripping to reveal etched resonators beneath an oxide membrane. Reliable bonding is assured by bonding unreleased structures which can withstand the appropriate pre-bond cleaning operations. The bonded oxide membrane serves as the basis of a surface micromachined membrane which incorporates silicon nitride and a porous polysilicon layer to facilitate release and supercritical drying. The cavity pressure is estimated to be in the range of 1 Torr. Encapsulated resonators were also made using a gap reduction process. The process is based on sidewall oxidation of an etched sleeve to reduce the linewidth of the patterned electrostatic gaps by 200 nm before the deep trench etch. Encapsulated and electrically active devices with gaps down to 500 nm were obtained and etched through a 5 µm thick SOI device layer. SEM images showed that gaps of 300 nm could reach through the same thickness, though functional devices were not obtained. In addition, limitations on the anti-notching process limited its use during the trench etch and resulted in severe notch damage.

  18. Development of Statistical Process Control Methodology for an Environmentally Compliant Surface Cleaning Process in a Bonding Laboratory

    NASA Technical Reports Server (NTRS)

    Hutchens, Dale E.; Doan, Patrick A.; Boothe, Richard E.

    1997-01-01

    Bonding labs at both MSFC and the northern Utah production plant prepare bond test specimens which simulate or witness the production of NASA's Reusable Solid Rocket Motor (RSRM). The current process for preparing the bonding surfaces employs 1,1,1-trichloroethane vapor degreasing, which simulates the current RSRM process. Government regulations (e.g., the 1990 Amendments to the Clean Air Act) have mandated a production phase-out of a number of ozone depleting compounds (ODC) including 1,1,1-trichloroethane. In order to comply with these regulations, the RSRM Program is qualifying a spray-in-air (SIA) precision cleaning process using Brulin 1990, an aqueous blend of surfactants. Accordingly, surface preparation prior to bonding process simulation test specimens must reflect the new production cleaning process. The Bonding Lab Statistical Process Control (SPC) program monitors the progress of the lab and its capabilities, as well as certifies the bonding technicians, by periodically preparing D6AC steel tensile adhesion panels with EA-91 3NA epoxy adhesive using a standardized process. SPC methods are then used to ensure the process is statistically in control, thus producing reliable data for bonding studies, and identify any problems which might develop. Since the specimen cleaning process is being changed, new SPC limits must be established. This report summarizes side-by-side testing of D6AC steel tensile adhesion witness panels and tapered double cantilevered beams (TDCBs) using both the current baseline vapor degreasing process and a lab-scale spray-in-air process. A Proceco 26 inches Typhoon dishwasher cleaned both tensile adhesion witness panels and TDCBs in a process which simulates the new production process. The tests were performed six times during 1995, subsequent statistical analysis of the data established new upper control limits (UCL) and lower control limits (LCL). The data also demonstrated that the new process was equivalent to the vapor

  19. Canada's physical activity guides: background, process, and development.

    PubMed

    Sharratt, Michael T; Hearst, William E

    2007-01-01

    This historical background paper chronicles the major events leading to the development of Canada's physical activity guides (for children, youth, adults, and older adults). The paper outlines the process and the steps used, including information (where applicable) regarding national partners, project administration, Health Canada communications, product development, endorsement, distribution and implementation, collateral activities, media relations and evaluation framework. Brief summaries of the science that led to the recommended guidelines are included. The paper also summarizes the various physical activity guide assessment and evaluation projects and their findings, particularly as they relate to research carried out on Canada's physical activity guides for children and youth (and the associated support resources).

  20. Processing Structures on Human Fingernail Surfaces Using a Focused Near-Infrared Femtosecond Laser Pulse

    NASA Astrophysics Data System (ADS)

    Hayasaki, Yoshio; Takagi, Hayato; Takita, Akihiro; Yamamoto, Hirotsugu; Nishida, Nobuo; Misawa, Hiroaki

    2004-12-01

    We investigated the processing of a human fingernail surface using a tightly focused femtosecond laser pulse. The processed structure in the fingernail surface is strongly dependent on the focus position and irradiation energy of the single laser pulse. We observed a ring, a simple pit, a small pit with a surrounding uplift, an irregular jagged surface, and a swell containing a void, depending on the focus position. We also observed a sudden change in the size of the processed structure according to the irradiation pulse energy. From a linear theoretical estimation based on the diffraction of the laser beam, we found that the sudden change is primarily due to the diffraction pattern generated by the circular aperture of the objective lens. We also describe the processing features by comparing the structures processed in a fingernail with those processed in glass.

  1. Development and in vitro evaluation of infection resistant materials: A novel surface modification process for silicone and Dacron.

    PubMed

    Hussain, Ali; Curry, Benjamin; Cahalan, Linda; Minkin, Steven; Gartner, Mark; Cahalan, Patrick

    2016-02-01

    Silicone and Dacron are used in a wide spectrum of implantable and indwelling medical products. They elicit a foreign body response, which results in a chronic inflammatory environment and collagenous encapsulation of the medical device that compromises the immune system's ability to effectively fight infections at the biomaterial surface. The objective of this work is to evaluate a novel process to modify silicone and Dacron with a bioactive collagen surface coupled to a gentamicin impregnated hydrogel graft and assess the surface's cytocompatibility and infection resistance properties. Samples of silicone and polyethylene terephthalate (Dacron velour) were modified by plasma deposition and activation followed by a co-polymer acrylic acid (AA)/acrylamide (AAm) hydrogel graft and covalent immobilization of a bioactive collagen surface. The modified surfaces were characterized using FTIR, contact angle, staining, SEM, and XPS. The poly (AA-AAm) hydrogel was impregnated with gentamicin and tested for controlled release characteristics. Each modified surface was evaluated for its ability to resist infection and to promote normal healing as measured by bacterial growth inhibition (Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) in both broth and agar conditions as well as using fluorescence microscopy to observe adherence of 3T3-NIH fibroblasts. The addition of the poly (AA-AAm) hydrogel with gentamicin inhibited bacterial growth and the subsequent addition of the collagen surface promoted robust fibroblast adhesion on both silicone and Dacron materials. Thorough surface characterization and in vitro bacterial and fibroblast evaluation results suggest that this novel surface bioengineering process generated a highly effective surface on silicone and Dacron with the potential to reduce infection and promote healing.

  2. Atomic-Scale Surface Local Structure of TiO2 and Its Influence on the Water Photooxidation Process.

    PubMed

    Imanishi, Akihito; Fukui, Ken-Ichi

    2014-06-19

    The water photooxidation reaction on TiO2 and related metal oxides has been attracting strong attention from the point of view of solar water splitting. The water photooxidation reaction (i.e., oxygen evolution reaction) accompanies three other kinds of side reactions (photoluminescence (PL), surface roughening, and nonradiative recombination). These reactions are competitive with each other, and the ratio of their quantum efficiencies strongly depends on the atomic-scale surface local structure. This Perspective focuses on the atomic-scale surface local structure dependence of those four kinds of competitive reactions on a TiO2 (rutile) single-crystal electrode on which not only a terrace structure but also step structures were strictly controlled. The experimental results are discussed based on the reaction model of water photooxidation that we previously proposed. The photocatalytic activity of the TiO2 surface roughened by the photoinduced roughening process is also focused on.

  3. NONLINEAR OPTICS: Nonlinear optical processes in planar waveguides and excitation of surface polaritons

    NASA Astrophysics Data System (ADS)

    Yashkir, O. V.; Yashkir, Yu N.

    1987-11-01

    An investigation is made of nonlinear optical interaction of light propagating in a planar waveguide with surface polaritons. Reduced wave equations for the amplitudes of the waveguide modes and surface polaritons are used to study the characteristics of generation of surface polaritons of difference frequency, parametric frequency up-conversion of the polaritons, and stimulated Raman scattering by the polaritons. An analysis is made of the characteristic properties of the investigated nonlinear optical processes.

  4. Immunoadjuvant activity of the nanoparticles’ surface modified with mannan

    NASA Astrophysics Data System (ADS)

    Haddadi, Azita; Hamdy, Samar; Ghotbi, Zahra; Samuel, John; Lavasanifar, Afsaneh

    2014-09-01

    Mannan (MN) is the natural ligand for mannose receptors, which are widely expressed on dendritic cells (DCs). The purpose of this study was to assess the effect of formulation parameters on the immunogenicity of MN-decorated poly (D, L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) in terms of their ability to stimulate DC phenotypic as well as functional maturation. For this purpose, NPs were formulated from either ester-terminated or COOH-terminated PLGA. Incorporation of MN in NPs was achieved through encapsulation, physical adsorption or chemical conjugation. Murine bone marrow derived DCs (BMDCs) were treated with various NP formulations and assessed for their ability to up-regulate DC cell surface markers, secrete immunostimulatory cytokines and to activate allogenic T cell responses. DCs treated with COOH-terminated PLGA-NPs containing chemically conjugated MN (MN-Cov-COOH) have shown superior performance in improving DC biological functions, compared to the rest of the formulations tested. This may be attributed to the higher level of MN incorporation in the former formulation. Incorporation of MN in PLGA NPs through chemical conjugation can lead to enhanced DC maturation and stimulatory function. This strategy may be used to develop more effective PLGA-based vaccine formulations.

  5. Assessing the Antimicrobial Activity of Polyisoprene Based Surfaces

    PubMed Central

    Badawy, Hope; Brunellière, Jérôme; Veryaskina, Marina; Brotons, Guillaume; Sablé, Sophie; Lanneluc, Isabelle; Lambert, Kelly; Marmey, Pascal; Milsted, Amy; Cutright, Teresa; Nourry, Arnaud; Mouget, Jean-Luc; Pasetto, Pamela

    2015-01-01

    There has been an intense research effort in the last decades in the field of biofouling prevention as it concerns many aspects of everyday life and causes problems to devices, the environment, and human health. Many different antifouling and antimicrobial materials have been developed to struggle against bacteria and other micro- and macro-organism attachment to different surfaces. However the “miracle solution” has still to be found. The research presented here concerns the synthesis of bio-based polymeric materials and the biological tests that showed their antifouling and, at the same time, antibacterial activity. The raw material used for the coating synthesis was natural rubber. The polyisoprene chains were fragmented to obtain oligomers, which had reactive chemical groups at their chain ends, therefore they could be modified to insert polymerizable and biocidal groups. Films were obtained by radical photopolymerization of the natural rubber derived oligomers and their structure was altered, in order to understand the mechanism of attachment inhibition and to increase the efficiency of the anti-biofouling action. The adhesion of three species of pathogenic bacteria and six strains of marine bacteria was studied. The coatings were able to inhibit bacterial attachment by contact, as it was verified that no detectable leaching of toxic molecules occurred. PMID:25706513

  6. Anionic Gemini Surfactants:. Synthesis and Surface Active Properties

    NASA Astrophysics Data System (ADS)

    Shukla, Dipti; Tyagi, V. K.

    New compounds bearing two phosphate groups and two long chain (dodecyl) were prepared by two-step reaction: (i) phosphorylation of dodecanol with pyrophosphoric acid, (ii) reaction of dodecyl phosphate with N(CH3)4OH and 1,6-dibromo hexane. The effect of reaction variables like time and molar ratio of reactants on yield has also been reported. The 1:2:0.5 molar ratio of reactants (dodecyl phosphate, N(CH3)4OH, and Br(CH2)6 Br, respectively) and 3 h duration resulted to give maximum yield of anionic gemini surfactants. The structure of synthesized surfactant was investigated by modern analytical techniques, viz. FT-IR, 1H NMR, 13C NMR. Amphipathic disodium phosphates were obtained by neutralization of free acids with sodium hydroxide and their surface active properties in aqueous solution were measured. These disodium phosphates possessed 77.3% anionic content and showed good water solubility. Foaming properties and wetting ability were also evaluated.

  7. Guiding catalytically active particles with chemically patterned surfaces

    NASA Astrophysics Data System (ADS)

    Uspal, William; Popescu, Mihail; Dietrich, Siegfried; Tasinkevych, Mykola

    Catalytically active Janus particles in solution create gradients in the chemical composition of the solution along their surfaces, as well as along any nearby container walls. The former leads to self-phoresis, while the latter gives rise to chemi-osmosis, providing an additional contribution to self-motility. Chemi-osmosis strongly depends on the molecular interactions between the diffusing chemical species and the wall. We show analytically, using an approximate ``point-particle'' approach, that by chemically patterning a planar substrate (e.g., by adsorbing two different materials) one can direct the motion of Janus particles: the induced chemi-osmotic flows can cause particles to either ``dock'' at a chemical step between the two materials, or to follow a chemical stripe. These theoretical predictions are confirmed by full numerical calculations. Generically, docking occurs for particles which tend to move away from their catalytic caps, while stripe-following occurs in the opposite case. Our analysis reveals the physical mechanisms governing this behavior.

  8. Surface modification of activated carbons for CO 2 capture

    NASA Astrophysics Data System (ADS)

    Pevida, C.; Plaza, M. G.; Arias, B.; Fermoso, J.; Rubiera, F.; Pis, J. J.

    2008-09-01

    The reduction of anthropogenic CO 2 emissions to address the consequences of climate change is a matter of concern for all developed countries. In the short term, one of the most viable options for reducing carbon emissions is to capture and store CO 2 at large stationary sources. Adsorption with solid sorbents is one of the most promising options. In this work, two series of materials were prepared from two commercial activated carbons, C and R, by heat treatment with gaseous ammonia at temperatures in the 200-800 °C range. The aim was to improve the selectivity and capacity of the sorbents to capture CO 2, by introducing basic nitrogen-functionalities into the carbons. The sorbents were characterised in terms of texture and chemical composition. Their surface chemistry was studied through temperature-programmed desorption tests and X-ray photoelectron spectroscopy. The capture performance of the carbons was evaluated by using a thermogravimetric analyser to record mass uptakes by the samples when exposed to a CO 2 atmosphere.

  9. Don Juan Basin, Wright Valley, Antarctica: Model for Surface Processes on Mars

    NASA Astrophysics Data System (ADS)

    Englert, P.; Bishop, J. L.; Gibson, E. K.; Patel, S.; Koeberl, C.

    2014-09-01

    Mineral, chemical, and soluble salt composition of drill core samples from Don Juan Basin, Wright Valley, Antarctica, indicate that the formation of the most saline terrestrial pond may include groundwater discharge and near surface flow processes.

  10. Process for using surface strain measurements to obtain operational loads for complex structures

    NASA Technical Reports Server (NTRS)

    Richards, William Lance (Inventor); Ko, William L. (Inventor)

    2010-01-01

    The invention is an improved process for using surface strain data to obtain real-time, operational loads data for complex structures that significantly reduces the time and cost versus current methods.

  11. Linkages of Remote Sea Surface Temperatures and Atlantic Tropical Cyclone Activity Mediated by the African Monsoon

    SciTech Connect

    Taraphdar, Sourav; Leung, Lai-Yung R.; Hagos, Samson M.

    2015-01-28

    Warm sea surface temperatures (SSTs) in North Atlantic and Mediterranean (NAMED) can influence tropical cyclone (TC) activity in the tropical East Atlantic by modulating summer convection over western Africa. Analysis of 30 years of observations show that the NAMED SST is linked to a strengthening of the Saharan heat low and enhancement of moisture and moist static energy in the lower atmosphere over West Africa, which favors a northward displacement of the monsoonal front. These processes also lead to a northward shift of the African easterly jet that introduces an anomalous positive vorticity from western Africa to the main development region (50W–20E; 10N–20N) of Atlantic TC. By modulating multiple processes associated with the African monsoon, this study demonstrates that warm NAMED SST explains 8% of interannual variability of Atlantic TC frequency. Thus NAME SST may provide useful predictability for Atlantic TC activity on seasonal-to-interannual time scale.

  12. Role of hydroxyl groups on the stability and catalytic activity of Au clusters on rutile surface

    SciTech Connect

    Kent, Paul R

    2011-01-01

    Hydroxyls are present as surface terminations of transition metal oxides under ambient conditions and may modify the properties of supported catalysts. We perform first-principles density functional theory calculations to investigate the role of hydroxyls on the catalytic activity of supported gold clusters on TiO{sub 2} (rutile). We find that they have a long-range effect increasing the adhesion of gold clusters on rutile. While hydroxyls make one gold atom more electronegative, a more complex charge-transfer scenario is observed on larger clusters which are important for catalytic applications. This enhances the molecular adsorption and coadsorption energies of CO and O{sub 2}, thereby increasing the catalytic activity of gold clusters for CO oxidation, consistent with reported experiments. Hydroxyls at the interface between gold and rutile surface are most important to this process, even when not directly bound to gold. As such, accurate models of catalytic processes on gold and other catalysts should include the effect of surface hydroxyls.

  13. The effect of processing on the surface physical stability of amorphous solid dispersions.

    PubMed

    Yang, Ziyi; Nollenberger, Kathrin; Albers, Jessica; Moffat, Jonathan; Craig, Duncan; Qi, Sheng

    2014-11-01

    The focus of this study was to investigate the effect of processing on the surface crystallization of amorphous molecular dispersions and gain insight into the mechanisms underpinning this effect. The model systems, amorphous molecular dispersions of felodipine-EUDRAGIT® E PO, were processed both using spin coating (an ultra-fast solvent evaporation based method) and hot melt extrusion (HME) (a melting based method). Amorphous solid dispersions with drug loadings of 10-90% (w/w) were obtained by both processing methods. Samples were stored under 75% RH/room temperatures for up to 10months. Surface crystallization was observed shortly after preparation for the HME samples with high drug loadings (50-90%). Surface crystallization was characterized by powder X-ray diffraction (PXRD), ATR-FTIR spectroscopy and imaging techniques (SEM, AFM and localized thermal analysis). Spin coated molecular dispersions showed significantly higher surface physical stability than hot melt extruded samples. For both systems, the progress of the surface crystal growth followed zero order kinetics on aging. Drug enrichment at the surfaces of HME samples on aging was observed, which may contribute to surface crystallization of amorphous molecular dispersions. In conclusion it was found the amorphous molecular dispersions prepared by spin coating had a significantly higher surface physical stability than the corresponding HME samples, which may be attributed to the increased process-related apparent drug-polymer solubility and reduced molecular mobility due to the quenching effect caused by the rapid solvent evaporation in spin coating.

  14. The effects of land surface process perturbations in a global ensemble forecast system

    NASA Astrophysics Data System (ADS)

    Deng, Guo; Zhu, Yuejian; Gong, Jiandong; Chen, Dehui; Wobus, Richard; Zhang, Zhe

    2016-10-01

    Atmospheric variability is driven not only by internal dynamics, but also by external forcing, such as soil states, SST, snow, sea-ice cover, and so on. To investigate the forecast uncertainties and effects of land surface processes on numerical weather prediction, we added modules to perturb soil moisture and soil temperature into NCEP's Global Ensemble Forecast System (GEFS), and compared the results of a set of experiments involving different configurations of land surface and atmospheric perturbation. It was found that uncertainties in different soil layers varied due to the multiple timescales of interactions between land surface and atmospheric processes. Perturbations of the soil moisture and soil temperature at the land surface changed sensible and latent heat flux obviously, as compared to the less or indirect land surface perturbation experiment from the day-to-day forecasts. Soil state perturbations led to greater variation in surface heat fluxes that transferred to the upper troposphere, thus reflecting interactions and the response to atmospheric external forcing. Various verification scores were calculated in this study. The results indicated that taking the uncertainties of land surface processes into account in GEFS could contribute a slight improvement in forecast skill in terms of resolution and reliability, a noticeable reduction in forecast error, as well as an increase in ensemble spread in an under-dispersive system. This paper provides a preliminary evaluation of the effects of land surface processes on predictability. Further research using more complex and suitable methods is needed to fully explore our understanding in this area.

  15. Process Of Bonding A Metal Brush Structure To A Planar Surface Of A Metal Substrate

    DOEpatents

    Slattery, Kevin T.; Driemeyer, Daniel E.; Wille; Gerald W.

    1999-11-02

    Process for bonding a metal brush structure to a planar surface of a metal substrate in which an array of metal rods are retained and immobilized at their tips by a common retention layer formed of metal, and the brush structure is then joined to a planar surface of a metal substrate via the retention layer.

  16. Photoinduced radical processes on the spinel (MgAl2O4) surface involving methane, ammonia, and methane/ammonia.

    PubMed

    Emeline, A V; Abramkin, D A; Zonov, I S; Sheremetyeva, N V; Rudakova, A V; Ryabchuk, V K; Serpone, N

    2012-05-15

    The present study explored photoinduced radical processes caused by interaction of CH(4) and NH(3) with a photoexcited surface of a complex metal oxide: magnesium-aluminum spinel (MgAl(2)O(4); MAS). UV irradiation of MAS in vacuo yielded V-type color centers as evidenced by the 360 nm band in difference diffuse reflectance spectra. Interaction of these H-bearing molecules with photogenerated surface-active hole states (O(S)(-)•) yielded radical species which on recombination produced more complex molecules (including heteroatomic species) relative to the initial molecules. For the MAS/CH(4) system, photoinduced dissociative adsorption of CH(4) on surface-active hole centers produced •CH(3) radicals that recombined to yield CH(3)CH(3). For MAS/NH(3), a similar dissociative adsorption process led to formation of •NH(2) radicals with formation of NH(2)NH(2) as an intermediate product; continued UV irradiation ultimately yielded N(2). For the mixed MAS/CH(4)/NH(3) system, however, interaction of adsorbed NH(3) and CH(4) on the UV-activated surface of MAS yielded •NH(2) and •CH(3) radicals, respectively, which produced CH(3)-NH(2) followed by loss of the remaining hydrogens to form a surface-adsorbed cyanide, CN(S), species. Recombination of photochemically produced radicals released sufficient energy to re-excite the solid spinel, generating new surface-active sites and a flash luminescence (emission decay time at 520 nm, τ ~ 6 s for the MAS/NH(3) case) referred to as the PhICL effect.

  17. Virus activity on the surface of glaciers and ice sheets

    NASA Astrophysics Data System (ADS)

    Bellas, C. M.; Anesio, A. M.; Telling, J.; Stibal, M.; Barker, G.; Tranter, M.; Yallop, M.; Cook, J.

    2012-12-01

    Viruses are found wherever there is life. They are major components of aquatic ecosystems and through interactions with their hosts they significantly alter global biogeochemical cycles and drive evolutionary processes. Here we focus on the interactions between bacteriophages and their hosts inhabiting the microbially dominated supraglacial ecosystems known as cryoconite holes. The diversity of phages present in the sediments of cryoconites was examined for the first time by using a molecular based approach to target the T4-type bacteriophage. Through phylogenetic analysis it was determined that the phage community was diverse, consisting of strains that grouped with those from other global habitats and those that formed several completely new T4-type phage clusters. The activity of the viral community present on glaciers from Svalbard and the Greenland Ice Sheet was also addressed through a series of incubation experiments. Here new virus production was found to be capable of turning over the viral population approximately twice a day, a rate comparable to marine and freshwater sediments around the globe. This large scale viral production was found to be theoretically capable of accounting for all heterotrophic bacterial mortality in cryoconite holes. The mode of infection that viruses employ in cryoconite holes was also addressed to show that a variety of viral life strategies are likely responsible for the continued dominance of viruses in these unique habitats. The implications of viral activity are discussed in terms of carbon cycling in supraglacial ecosystems.

  18. Process flow to integrate nanostructures on silicon grass in surface micromachined systems

    NASA Astrophysics Data System (ADS)

    Mehner, H.; Müller, L.; Biermann, S.; Hänschke, F.; Hoffmann, M.

    2016-10-01

    The process flow to integrate metallic nanostructures in surface micromachining processes is presented. The nanostructures are generated by evaporation of microstructured silicon grass with metal. The process flow is based on the lift-off of a thin amorphous silicon layer deposited using a CVD process. All steps feature a low temperature load beneath 120 °C and high compatibility with many materials as only well-established chemicals are used. As a result metallic nanostructures usable for optical applications can be generated as part of multilayered microsystems fabricated in surface micromachining.

  19. Superhydrophobic surface with hierarchical architecture and bimetallic composition for enhanced antibacterial activity.

    PubMed

    Zhang, Mei; Wang, Ping; Sun, Hongyan; Wang, Zuankai

    2014-12-24

    Developing robust antibacterial materials is of importance for a wide range of applications such as in biomedical engineering, environment, and water treatment. Herein we report the development of a novel superhydrophobic surface featured with hierarchical architecture and bimetallic composition that exhibits enhanced antibacterial activity. The surface is created using a facile galvanic replacement reaction followed by a simple thermal oxidation process. Interestingly, we show that the surface's superhydrophobic property naturally allows for a minimal bacterial adhesion in the dry environment, and also can be deactivated in the wet solution to enable the release of biocidal agents. In particular, we demonstrate that the higher solubility nature of the thermal oxides created in the thermal oxidation process, together with the synergistic cooperation of bimetallic composition and hierarchical architecture, allows for the release of metal ions in a sustained and accelerated manner, leading to enhanced antibacterial performance in the wet condition as well. We envision that the ease of fabrication, the versatile functionalities, and the robustness of our surface will make it appealing for broad applications.

  20. Constrained Broyden Dimer Method with Bias Potential for Exploring Potential Energy Surface of Multistep Reaction Process.

    PubMed

    Shang, Cheng; Liu, Zhi-Pan

    2012-07-10

    To predict the chemical activity of new matter is an ultimate goal in chemistry. The identification of reaction pathways using modern quantum mechanics calculations, however, often requires a high demand in computational power and good chemical intuition on the reaction. Here, a new reaction path searching method is developed by combining our recently developed transition state (TS) location method, namely, the constrained Broyden dimer method, with a basin-filling method via bias potentials, which allows the system to walk out from the energy traps at a given reaction direction. In the new method, the reaction path searching starts from an initial state without the need for preguessing the TS-like or final state structure and can proceed iteratively to the final state by locating all related TSs and intermediates. In each elementary reaction step, a reaction direction, such as a bond breaking, needs to be specified, the information of which is refined and preserved as a normal mode through biased dimer rotation. The method is tested successfully on the Baker reaction system (50 elementary reactions) with good efficiency and stability and is also applied to the potential energy surface exploration of multistep reaction processes in the gas phase and on the surface. The new method can be applied for the computational screening of new catalytic materials with a minimum requirement of chemical intuition.