WorldWideScience

Sample records for surface response function

  1. Development of Biomimetic and Functionally Responsive Surfaces

    Science.gov (United States)

    Anastasiadis, Spiros H.

    2010-03-01

    Controlling the surface morphology of solids and manufacturing of functional surfaces with special responsive properties has been the subject of intense research. We report a methodology for creating multifunctionally responsive surfaces by irradiating silicon wafers with femtosecond laser pulses and subsequently coating them with different types of functional conformal coatings. Such surfaces exhibit controlled dual-scale roughness at the micro- and the nano-scale, which mimics the hierarchical morphology of water repellent natural surfaces. When a simple alkylsilane coating is utilized, highly water repellent surfaces are produced that quantitatively compare to those of the Lotus leaf. When a polymer brush is ``grafted from" these surfaces based on a pH-sensitive polymer, the surfaces can alter their behavior from super-hydrophilic (after immersion in a low pH buffer) to super-hydrophobic and water-repellent (following immersion to a high pH buffer). We quantify the water repellency of such responsive systems by drop elasticity measurements whereas we demonstrate that the water repellent state of such surface requires appropriate hydrophobicity of the functionalizing polymer. When a photo-responsive azobenzene-type polymer is deposited, a dynamic optical control of the wetting properties is obtained and the surface can be switched from super-hydrophilic (following UV irradiation) to hydrophobic (following green irradiation). In all the above cases we show that the principal effect of roughness is to cause amplification of the response to the different external stimuli.

  2. Response functions for crystals and surfaces, with applications to surface scattering

    International Nuclear Information System (INIS)

    Barker, J.A.; Steele, W.A.

    1978-01-01

    A general solution of the equations of forced motion of a harmonic crystal or other vibrating system with arbitrary time-dependent forces acting on the atoms is given. The solution is given in terms of dynamical 'response functions', for which expressions in terms of the normal mode frequencies and eigenvectors (polarization vectors) are given. Numerical calculations of the response functions are described for (111) and (100) surfaces of face-centered cubic crystals interacting with Lennard-Jones 6-12 potentials, and the qualitative features of the surface and bulk response functions are discussed. The use of these functions in problems of atomic scattering from surface is outlined, and convenient parametrized forms for this application are given. (Auth.)

  3. Kinetic response study in chemiresistive gas sensor based on carbon nanotube surface functionalized with substituted phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Anshul Kumar; Saini, Rajan; Bedi, R. K.; Mahajan, Aman, E-mail: dramanmahajan@yahoo.co.in, E-mail: anshulsharma.phy@gmail.com [Material Science Laboratory, Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Kumar, Pankaj [Department of Applied Sciences, I.K. Gujral Punjab Technical University, Kapurthala 144601 (India)

    2016-05-06

    A kind of hybrid material is prepared by functionalizing multi-wall carbon nanotubes (MWCNTs-COOH) with substituted copper phthalocyanine and the formation of CuPcOC{sub 8}/MWCNTs-COOH hybrid is confirmed by scanning electron microscopy and transmission electron microscopy. The results indicated that on the surface of nanotubes substituted CuPcOC{sub 8} derivatives has been successfully anchored through π-π stacking interaction. The gas sensing application of the fabricated hybrid material is tested upon exposure to different hazardous species, specifically NO{sub 2}, NO, Cl{sub 2} and NH{sub 3} at operating temperature of 150°C. It has been demonstrated that for Cl{sub 2} minimum detection limit of CuPcOC{sub 8}/MWCNTs-COOH hybrid is 100 ppb. The response of hybrid sensor is found to be increased with increase in the concentration of Cl{sub 2}.

  4. Kinetic response study in chemiresistive gas sensor based on carbon nanotube surface functionalized with substituted phthalocyanines

    Science.gov (United States)

    Sharma, Anshul Kumar; Kumar, Pankaj; Saini, Rajan; Bedi, R. K.; Mahajan, Aman

    2016-05-01

    A kind of hybrid material is prepared by functionalizing multi-wall carbon nanotubes (MWCNTs-COOH) with substituted copper phthalocyanine and the formation of CuPcOC8/MWCNTs-COOH hybrid is confirmed by scanning electron microscopy and transmission electron microscopy. The results indicated that on the surface of nanotubes substituted CuPcOC8 derivatives has been successfully anchored through π-π stacking interaction. The gas sensing application of the fabricated hybrid material is tested upon exposure to different hazardous species, specifically NO2, NO, Cl2 and NH3 at operating temperature of 150˚C. It has been demonstrated that for Cl2 minimum detection limit of CuPcOC8/MWCNTs-COOH hybrid is 100 ppb. The response of hybrid sensor is found to be increased with increase in the concentration of Cl2.

  5. Optimization of a Functional Cookie Formulation by Using Response Surface Methodology

    International Nuclear Information System (INIS)

    Lee, L.Y.; Tan, K.S.; Liew, S.L.

    2011-01-01

    A functional cookie formulation containing oligo fructose, dietary fibre and lower calorie, fat and sugar contents than conventional cookies was optimized using Response Surface Methodology (RSM). Instant N-Oil II was used as a fat replacer, while Raftilose P95 was used as a sugar substitute with the addition of fructose to enhance sweetness. Selection of the optimal formulation was based on caloric content. An optimized formulation, V1, was obtained from the model Y = 4927.70 - 152.34X 1 - 155.42X 3 + 104.20X 3 2 + 151.71X 3 3 - 95.08X 3 4 , where Instant N-Oil II replaced 30 % of butter and 24.4 %, w/w (30.5 g) fructose replaced 40.0 %, w/w (50.0 g) sucrose. Two additional optimized formulations, S1 and S2, were proposed which contained the same ingredients as V1, but both contained 19.0 %, w/w (23.8 g) Raftilose P95. Also, S2 had a higher fat replacement level (42 %). A reference cookie prepared from a conventional recipe received significantly higher scores (P < 0.05) than the functional cookies V1, S1 and S2 in the sensory evaluation. However, when health benefits of the functional cookies were explained to the panel after the sensory evaluation had concluded, majority of the panelists stated that they would prefer S1, had they known of its health benefits. S1 contained 19.04 % fat, 8.62 % fructose and 0.74 % sucrose, namely, significantly lower fat and sucrose levels and higher fructose content than the conventional cookie. (author)

  6. Microgel-based surface modifying system for stimuli-responsive functional finishing of cotton

    NARCIS (Netherlands)

    Kulkarni, A.N.; Tourrette, A.; Warmoeskerken, Marinus; Jocic, D.

    2010-01-01

    An innovative strategy for functional finishing of textile materials is based on the incorporation of a thin layer of surface modifying systems (SMS) in the form of stimuli-sensitive microgels or hydrogels. Since the copolymerization of poly(N-isopropylacrylamide) with an ionizable polymer, such as

  7. Adsorption of cellulase on cereal brans: a simple functional model from response surface methodology

    Directory of Open Access Journals (Sweden)

    Rui Sergio F. da Silva

    1980-11-01

    Full Text Available A functional model based on Langmuirian adsorption as a limiting mechanism was proposed to explain the effect of cellulase during the enzymatic pretreatment of bran, conducted prior to extraction of proteins, by wet alkaline process from wheat and buckwheat bran materials. The proposed model provides a good fit (r = 0.99 for the data generated thru predictive model taken from the response surface methodology, permitting calculation of a affinity constant (b and capacity constant (k, for wheat bran (b = 0.255 g/IU and k = 17.42% and buckwheat bran (b = 0.066g/IUand k = 78.74%.Modelo funcional baseado na adsorção de Langmuir como mecanismo limitante proposto para explicar o efeito da celulase durante o pré-tratamento enzimático de farelos, visando à extração de proteínas, através do método alcalino-úmido. O referido modelo ajusta se muito bem (r = 0,99 aos dados gerados com base em modelo preditivo obtido da metodologia da superfície de resposta. Pode-se calcular a constante de afinidade (b e a constante de capacidade (k para o farelo de trigo e farelo de trigo mourisco (sarraceno, usando uma equação análoga à isoterma de adsorção de Langmuir. Os resultados indicaram que o farelo de trigo mourisco apresenta uma capacidade mais alta para adsorver celulase e, conseqüentemente,'pode-se esperar uma resposta maior ao pré-tratamento com esta enzima.

  8. Functionalization of graphene and grafting of temperature-responsive surfaces from graphene by ATRP 'on water'

    Energy Technology Data Exchange (ETDEWEB)

    Ren Lulu; Huang Shu; Zhang Chao; Wang Ruiyu [Fudan University, State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science (China); Tjiu, Weng Weei [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR) (Singapore); Liu Tianxi, E-mail: txliu@fudan.edu.cn [Fudan University, State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science (China)

    2012-06-15

    Water-dispersible graphene with temperature-responsive surfaces has successfully been synthesized by grafting poly(N-isopropylacrylamide) (PNIPAM) from graphene via surface-initiated atom transfer radical polymerization (ATRP). First, graphene surfaces are functionalized with aminophenol groups by diazonium reaction on water. Subsequently, bromoisobutyrate groups are covalently attached to the phenol-functionalized graphene (G-OH) surface by esterification of 2-bromoisobutyrate with the hydroxyl groups, forming bromoisobutyrate-functionalized graphene (G-Br). Finally, PNIPAM is then grafted from G-Br via ATRP. Data from Raman spectroscopy, {sup 1}H NMR, and transmission electron microscopy (TEM) confirm that PNIPAM chains grow from graphene by ATRP. Thermogravimetric analysis shows that the amount of PNIPAM grown from the graphene increases with the increase of monomer ratios. TEM images also show that functionalized polymer structures (PNIPAM cluster or agglutination) on graphene sheets can be well tuned by controlled polymerization. The obtained graphene-PNIPAM (G-PNIPAM) composite has PNIPAM surface which is highly sensitive to the temperature change. This temperature-responsive and water-dispersible G-PNIPAM composite may find potential applications in environmental devices as well as controlled release drug delivery.

  9. Response of the Shockley surface state to an external electrical field: A density-functional theory study of Cu(111)

    Science.gov (United States)

    Berland, K.; Einstein, T. L.; Hyldgaard, P.

    2012-01-01

    The response of the Cu(111) Shockley surface state to an external electrical field is characterized by combining a density-functional theory calculation for a slab geometry with an analysis of the Kohn-Sham wave functions. Our analysis is facilitated by a decoupling of the Kohn-Sham states via a rotation in Hilbert space. We find that the surface state displays isotropic dispersion, quadratic until the Fermi wave vector but with a significant quartic contribution beyond. We calculate the shift in energetic position and effective mass of the surface state for an electrical field perpendicular to the Cu(111) surface; the response is linear over a broad range of field strengths. We find that charge transfer occurs beyond the outermost copper atoms and that accumulation of electrons is responsible for a quarter of the screening of the electrical field. This allows us to provide well converged determinations of the field-induced changes in the surface state for a moderate number of layers in the slab geometry.

  10. Response Surface Methodology

    NARCIS (Netherlands)

    Kleijnen, Jack P.C.

    2014-01-01

    Abstract: This chapter first summarizes Response Surface Methodology (RSM), which started with Box and Wilson’s article in 1951 on RSM for real, non-simulated systems. RSM is a stepwise heuristic that uses first-order polynomials to approximate the response surface locally. An estimated polynomial

  11. Functional response of a near-surface soil microbial community to a simulated underground CO2 storage leak.

    Science.gov (United States)

    Morales, Sergio E; Holben, William E

    2013-01-01

    Understanding the impacts of leaks from geologic carbon sequestration, also known as carbon capture and storage, is key to developing effective strategies for carbon dioxide (CO2) emissions management and mitigation of potential negative effects. Here, we provide the first report on the potential effects of leaks from carbon capture and storage sites on microbial functional groups in surface and near-surface soils. Using a simulated subsurface CO2 storage leak scenario, we demonstrate how CO2 flow upward through the soil column altered both the abundance (DNA) and activity (mRNA) of microbial functional groups mediating carbon and nitrogen transformations. These microbial responses were found to be seasonally dependent and correlated to shifts in atmospheric conditions. While both DNA and mRNA levels were affected by elevated CO2, they did not react equally, suggesting two separate mechanisms for soil microbial community response to high CO2 levels. The results did not always agree with previous studies on elevated atmospheric (rather than subsurface) CO2 using FACE (Free-Air CO2 Enrichment) systems, suggesting that microbial community response to CO2 seepage from the subsurface might differ from its response to atmospheric CO2 increases.

  12. Sensitivity of Surface Temperature to Oceanic Forcing via q-Flux Green’s Function Experiments. Part I: Linear Response Function

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fukai; Lu, Jian; Garuba, Oluwayemi A.; Leung, Lai-Yung; Luo, Yiyong; Wan, Xiuquan

    2018-05-01

    This paper explores the use of linear response function (LRF) to relate the mean sea surface temperature (SST) response to prescribed ocean heat convergence (q-flux) forcings. Two methods for constructing the LRF based on the fluctuation-dissipation theorem (FDT) and Green’s function (GRF) are examined. A 900-year preindustrial simulation from the Community Earth System Model with a slab ocean (CESM-SOM) is used to estimate the LRF using FDT. For GRF, 106 pairs of CESM-SOM simulations with warm and cold q-flux patches are performed. FDT is found to have skill in estimating the SST response to a q-flux forcing when the local SST response is strong, but it fails in inverse estimation of the q-flux forcing for a given SST pattern. In contrast, GRF is shown to be reasonably accurate in estimating both SST response and q-flux forcing. Possible degradation in FDT may be attributed to insufficient data sampling, significant departures of the SST data from Gaussian, and the non-normality of the constructed operator. The accurately estimated GRF-based LRF is used to (i) generate a global surface temperature sensitivity map that shows the q-flux forcing in higher latitudes to be three to four times more effective than in low latitudes in producing global surface warming; (ii) identify the most excitable SST mode (neutral vector) resembling Interdecadal Pacific Oscillation; and (iii) estimate a time-invariant q-flux forcing needed for maintaining the GHG-induced SST warming pattern. The GRF experiments will be used to construct LRF for other variables to further explore climate sensitivities and feedbacks.

  13. Response of the Shockley surface state on Cu(111) to an external electrical field: A density-functional theory study

    Science.gov (United States)

    Berland, Kristian; Hyldgaard, Per; Einstein, T. L.

    2011-03-01

    We study the response of the Cu(111) Shockley surface state to an external electrical field E by combining a density-functional theory calculation for a finite slab geometry with an analysis of the Kohn-Sham wavefunctions to obtain a well-converged characterization. We find that the surface state displays isotropic dispersion, quadratic until the Fermi wave vector but with a significant quartic contribution beyond. We find that the shift in band minimum and effective mass depend linearly on E. Most change in electrostatic potential profile, and charge transfer occurs outside the outermost copper atoms, and most of the screening is due to bulk electrons. Our analysis is facilitated by a method used to decouple the Kohn-Sham states due to the finite slab geometry, using a rotation in Hilbert space. We discuss applications to tuning the Fermi wavelength and so the many patterns attributed to metallic surface states. Supported by (KB and PH) Swedish Vetenskapsrådet VR 621-2008-4346 and (TLE) NSF CHE 07-50334 & UMD MRSEC DMR 05-20471.

  14. Responsive acoustic surfaces

    DEFF Research Database (Denmark)

    Peters, Brady; Tamke, Martin; Nielsen, Stig Anton

    2011-01-01

    Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... for the acoustic conditions of these spaces. This paper describes an experimental research project that studied the design processes necessary to design for sound. A responsive acoustic surface was designed, fabricated and tested. This acoustic surface was designed to create specific sonic effects. The design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....

  15. An Improvement in Biodiesel Production from Waste Cooking Oil by Applying Thought Multi-Response Surface Methodology Using Desirability Functions

    Directory of Open Access Journals (Sweden)

    Marina Corral Bobadilla

    2017-01-01

    Full Text Available The exhaustion of natural resources has increased petroleum prices and the environmental impact of oil has stimulated the search for an alternative source of energy such as biodiesel. Waste cooking oil is a potential replacement for vegetable oils in the production of biodiesel. Biodiesel is synthesized by direct transesterification of vegetable oils, which is controlled by several inputs or process variables, including the dosage of catalyst, process temperature, mixing speed, mixing time, humidity and impurities of waste cooking oil that was studied in this case. Yield, turbidity, density, viscosity and higher heating value are considered as outputs. This paper used multi-response surface methodology (MRS with desirability functions to find the best combination of input variables used in the transesterification reactions to improve the production of biodiesel. In this case, several biodiesel optimization scenarios have been proposed. They are based on a desire to improve the biodiesel yield and the higher heating value, while decreasing the viscosity, density and turbidity. The results demonstrated that, although waste cooking oil was collected from various sources, the dosage of catalyst is one of the most important variables in the yield of biodiesel production, whereas the viscosity obtained was similar in all samples of the biodiesel that was studied.

  16. Experimental study of the response functions of direct-reading instruments measuring surface-area concentration of airborne nanostructured particles

    International Nuclear Information System (INIS)

    Bau, Sebastien; Witschger, Olivier; Gensdarmes, Francois; Thomas, Dominique

    2009-01-01

    An increasing number of experimental and theoretical studies focus on airborne nanoparticles (NP) in relation with many aspects of risk assessment to move forward our understanding of the hazards, the actual exposures in the workplace, and the limits of engineering controls and personal protective equipment with regard to NP. As a consequence, generating airborne NP with controlled properties constitutes an important challenge. In parallel, toxicological studies have been carried out, and most of them support the concept that surface-area could be a relevant metric for characterizing exposure to airborne NP. To provide NP surface-area concentration measurements, some direct-reading instruments have been designed, based on attachment rate of unipolar ions to NP by diffusion. However, very few information is available concerning the performances of these instruments and the parameters that could affect their responses. In this context, our work aims at characterizing the actual available instruments providing airborne NP surface-area concentration. The instruments (a- LQ1-DC, Matter Engineering; b-AeroTrak x2122 9000, TSI; c- NSAM, TSI model 3550;) are thought to be relevant for further workplace exposure characterization and monitoring. To achieve our work, an experimental facility (named CAIMAN) was specially designed, built and characterized.

  17. Experimental study of the response functions of direct-reading instruments measuring surface-area concentration of airborne nanostructured particles

    Energy Technology Data Exchange (ETDEWEB)

    Bau, Sebastien; Witschger, Olivier [Institut National de Recherche et de Securite, INRS, Laboratoire de Metrologie des Aerosols, Rue du Morvan, CS 60027, 54519 Vandoeuvre Cedex (France); Gensdarmes, Francois [Institut de Radioprotection et de Surete Nucleaire, IRSN, Laboratoire de Physique et de Metrologie des Aerosols, BP 68, 91192 Gif-sur-Yvette Cedex (France); Thomas, Dominique [Laboratoire des Sciences du Genie Chimique, LSGC/CNRS, Nancy Universite, BP 2041, 54001 Nancy Cedex (France)], E-mail: sebastien.bau@inrs.fr

    2009-05-01

    An increasing number of experimental and theoretical studies focus on airborne nanoparticles (NP) in relation with many aspects of risk assessment to move forward our understanding of the hazards, the actual exposures in the workplace, and the limits of engineering controls and personal protective equipment with regard to NP. As a consequence, generating airborne NP with controlled properties constitutes an important challenge. In parallel, toxicological studies have been carried out, and most of them support the concept that surface-area could be a relevant metric for characterizing exposure to airborne NP. To provide NP surface-area concentration measurements, some direct-reading instruments have been designed, based on attachment rate of unipolar ions to NP by diffusion. However, very few information is available concerning the performances of these instruments and the parameters that could affect their responses. In this context, our work aims at characterizing the actual available instruments providing airborne NP surface-area concentration. The instruments (a- LQ1-DC, Matter Engineering; b-AeroTrak{sup x2122} 9000, TSI; c- NSAM, TSI model 3550;) are thought to be relevant for further workplace exposure characterization and monitoring. To achieve our work, an experimental facility (named CAIMAN) was specially designed, built and characterized.

  18. Characterization of Genotoxic Response to 15 Multiwalled Carbon Nanotubes with Variable Physicochemical Properties Including Surface Functionalizations in the FE1-Muta(TM) Mouse Lung Epithelial Cell Line

    DEFF Research Database (Denmark)

    Jackson, Petra; Kling, Kirsten; Jensen, Keld Alstrup

    2015-01-01

    Carbon nanotubes vary greatly in physicochemical properties. We compared cytotoxic and genotoxic response to 15 multiwalled carbon nanotubes (MWCNT) with varying physicochemical properties to identify drivers of toxic responses. The studied MWCNT included OECD Working Party on Manufactured...... Nanomaterials (WPMN) (NM-401, NM-402, and NM-403), materials (NRCWE-026 and MWCNT-XNRI-7), and three sets of surface-modified MWCNT grouped by physical characteristics (thin, thick, and short I-III, respectively). Each Groups I-III included pristine, hydroxylated and carboxylated MWCNT. Group III also included...... an amino-functionalized MWCNT. The level of surface functionalization of the MWCNT was low. The level and type of elemental impurities of the MWCNT varied by...

  19. Adaptive Response Surface Techniques in Reliability Estimation

    DEFF Research Database (Denmark)

    Enevoldsen, I.; Faber, M. H.; Sørensen, John Dalsgaard

    1993-01-01

    Problems in connection with estimation of the reliability of a component modelled by a limit state function including noise or first order discontinuitics are considered. A gradient free adaptive response surface algorithm is developed. The algorithm applies second order polynomial surfaces...

  20. Response surface use in safety analyses

    International Nuclear Information System (INIS)

    Prosek, A.

    1999-01-01

    When thousands of complex computer code runs related to nuclear safety are needed for statistical analysis, the response surface is used to replace the computer code. The main purpose of the study was to develop and demonstrate a tool called optimal statistical estimator (OSE) intended for response surface generation of complex and non-linear phenomena. The performance of optimal statistical estimator was tested by the results of 59 different RELAP5/MOD3.2 code calculations of the small-break loss-of-coolant accident in a two loop pressurized water reactor. The results showed that OSE adequately predicted the response surface for the peak cladding temperature. Some good characteristic of the OSE like monotonic function between two neighbor points and independence on the number of output parameters suggest that OSE can be used for response surface generation of any safety or system parameter in the thermal-hydraulic safety analyses.(author)

  1. The static friction response of non-glabrous skin as a function of surface energy and environmental conditions

    NARCIS (Netherlands)

    Klaassen, Michel; de Vries, Erik G.; Masen, Marc Arthur

    2017-01-01

    The (local) environmental conditions have a significant effect on the interaction between skin and products. Plasticisation of the stratum corneum occurs at high humidity, causing this layer to soften and change its surface free energy. In this work we study the effects of the micro-climate on the

  2. Dynamic bioactive stimuli-responsive polymeric surfaces

    Science.gov (United States)

    Pearson, Heather Marie

    This dissertation focuses on the design, synthesis, and development of antimicrobial and anticoagulant surfaces of polyethylene (PE), polypropylene (PP), and poly(tetrafluoroethylene) (PTFE) polymers. Aliphatic polymeric surfaces of PE and PP polymers functionalized using click chemistry reactions by the attachment of --COOH groups via microwave plasma reactions followed by functionalization with alkyne moieties. Azide containing ampicillin (AMP) was synthesized and subsequently clicked into the alkyne prepared PE and PP surfaces. Compared to non-functionalized PP and PE surfaces, the AMP clicked surfaces exhibited substantially enhanced antimicrobial activity against Staphylococcus aureus bacteria. To expand the biocompatibility of polymeric surface anticoagulant attributes, PE and PTFE surfaces were functionalized with pH-responsive poly(2-vinyl pyridine) (P2VP) and poly(acrylic acid) (PAA) polyelectrolyte tethers terminated with NH2 and COOH groups. The goal of these studies was to develop switchable stimuli-responsive polymeric surfaces that interact with biological environments and display simultaneous antimicrobial and anticoagulant properties. Antimicrobial AMP was covalently attached to --COOH terminal ends of protected PAA, while anticoagulant heparin (HEP) was attached to terminal --NH2 groups of P2VP. When pH 5.5, they collapse while the PAA segments extend. Such surfaces, when exposed to Staphylococcus aureus, inhibit bacterial growth due to the presence of AMP, as well as are effective anticoagulants due to the presence of covalently attached HEP. Comparison of these "dynamic" pH responsive surfaces with "static" surfaces terminated with AMP entities show significant enhancement of longevity and surface activity against microbial film formation. The last portion of this dissertation focuses on the covalent attachment of living T1 and Φ11 bacteriophages (phages) on PE and PTFE surface. This was accomplished by carbodiimide coupling between --COOH

  3. Effect of extrusion cooking on the functional properties and starch components of lentil/banana blends: Response surface analysis

    OpenAIRE

    Hernández-Nava, R.G.; Bello-Pérez, L.A.; San Martín-Martínez, E.; Hernández-Sánchez, H.; Mora-Escobedo, R.

    2011-01-01

    Banana and lentil flour blends were processed in a sing le screw extruder modifying the flour properties of the blend (20.5-79.5%), at selected range of die temperature (145-175 ºC) and the feeding moisture content (20-24%). Functional characteristics evaluated in the extrudates were water absorption index (WAI), water solubility index (WSI), bulk density (BD), paste viscosity properties, microstructure and resistant starch content. The concentration of lentil/banana blends and temperature we...

  4. Vicinal surfaces for functional nanostructures.

    Science.gov (United States)

    Tegenkamp, Christoph

    2009-01-07

    Vicinal surfaces are currently the focus of research. The regular arrangements of atomic steps on a mesoscopic scale reveal the possibility to functionalize these surfaces for technical applications, e.g. nanowires, catalysts, etc. The steps of the vicinal surface are well-defined defect structures of atomic size for nucleation of low-dimensional nanostructures. The concentration and therefore the coupling between the nanostructures can be tuned over a wide range by simply changing the inclination angle of the substrate. However, the coupling of these nano-objects to the substrate is just as important in controlling their electronic or chemical properties and making a functionality useable. On the basis of stepped insulating films, these aspects are fulfilled and will be considered in the first part of this review. Recent results for the epitaxial growth of wide bandgap insulating films (CaF(2), MgO, NaCl, BaSrO) on metallic and semiconducting vicinal substrates (Si(100), Ge(100), Ag(100)) will be presented. The change of the electronic structure, the adsorption behavior as well as the kinetics and energetics of color centers in the presence of steps is discussed. The successful bridging of the gap between the atomic and mesoscopic world, i.e. the functionalization of vicinal surfaces by nanostructures, is demonstrated in the second part by metal adsorption on semiconducting surfaces. For (sub)monolayer coverage these systems have in common that the surface states do not hybridize with the support, i.e. the semiconducting surfaces are insulating. Here I will focus on the latest results of macroscopic transport measurements on Pb quantum wires grown on vicinal Si(111) showing indeed a one-dimensional transport behavior.

  5. Vicinal surfaces for functional nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tegenkamp, Christoph [Institut fuer Festkoerperphysik, Gottfried Wilhelm Leibniz Universitaet Hannover, Appelstrasse 2, D-30167 Hannover (Germany)], E-mail: tegenkamp@fkp.uni-hannover.de

    2009-01-07

    Vicinal surfaces are currently the focus of research. The regular arrangements of atomic steps on a mesoscopic scale reveal the possibility to functionalize these surfaces for technical applications, e.g. nanowires, catalysts, etc. The steps of the vicinal surface are well-defined defect structures of atomic size for nucleation of low-dimensional nanostructures. The concentration and therefore the coupling between the nanostructures can be tuned over a wide range by simply changing the inclination angle of the substrate. However, the coupling of these nano-objects to the substrate is just as important in controlling their electronic or chemical properties and making a functionality useable. On the basis of stepped insulating films, these aspects are fulfilled and will be considered in the first part of this review. Recent results for the epitaxial growth of wide bandgap insulating films (CaF{sub 2}, MgO, NaCl, BaSrO) on metallic and semiconducting vicinal substrates (Si(100), Ge(100), Ag(100)) will be presented. The change of the electronic structure, the adsorption behavior as well as the kinetics and energetics of color centers in the presence of steps is discussed. The successful bridging of the gap between the atomic and mesoscopic world, i.e. the functionalization of vicinal surfaces by nanostructures, is demonstrated in the second part by metal adsorption on semiconducting surfaces. For (sub)monolayer coverage these systems have in common that the surface states do not hybridize with the support, i.e. the semiconducting surfaces are insulating. Here I will focus on the latest results of macroscopic transport measurements on Pb quantum wires grown on vicinal Si(111) showing indeed a one-dimensional transport behavior. (topical review)

  6. Vicinal surfaces for functional nanostructures

    International Nuclear Information System (INIS)

    Tegenkamp, Christoph

    2009-01-01

    Vicinal surfaces are currently the focus of research. The regular arrangements of atomic steps on a mesoscopic scale reveal the possibility to functionalize these surfaces for technical applications, e.g. nanowires, catalysts, etc. The steps of the vicinal surface are well-defined defect structures of atomic size for nucleation of low-dimensional nanostructures. The concentration and therefore the coupling between the nanostructures can be tuned over a wide range by simply changing the inclination angle of the substrate. However, the coupling of these nano-objects to the substrate is just as important in controlling their electronic or chemical properties and making a functionality useable. On the basis of stepped insulating films, these aspects are fulfilled and will be considered in the first part of this review. Recent results for the epitaxial growth of wide bandgap insulating films (CaF 2 , MgO, NaCl, BaSrO) on metallic and semiconducting vicinal substrates (Si(100), Ge(100), Ag(100)) will be presented. The change of the electronic structure, the adsorption behavior as well as the kinetics and energetics of color centers in the presence of steps is discussed. The successful bridging of the gap between the atomic and mesoscopic world, i.e. the functionalization of vicinal surfaces by nanostructures, is demonstrated in the second part by metal adsorption on semiconducting surfaces. For (sub)monolayer coverage these systems have in common that the surface states do not hybridize with the support, i.e. the semiconducting surfaces are insulating. Here I will focus on the latest results of macroscopic transport measurements on Pb quantum wires grown on vicinal Si(111) showing indeed a one-dimensional transport behavior. (topical review)

  7. Multi-Optimization of Ultrasonic-Assisted Enzymatic Extraction of Atratylodes macrocephala Polysaccharides and Antioxidants Using Response Surface Methodology and Desirability Function Approach.

    Science.gov (United States)

    Pu, Jin-Bao; Xia, Bo-Hou; Hu, Yi-Juan; Zhang, Hong-Jian; Chen, Jing; Zhou, Jie; Liang, Wei-Qing; Xu, Pan

    2015-12-11

    Rhizoma Atractylodes macrocephala polysaccharides (RAMP) have been reported to have a variety of important biological activities. In this study, an ultrasonic-assisted enzymatic extraction (UAEE) was employed to obtain the highest extraction yield and strongest antioxidant activity of RAMP and optimized by a multi-response optimization process. A three-level four-factor Box-Behnken design (BBD) was performed as response surface methodology (RSM) with desirability function (DF) to attain the optimal extraction parameters. The DPPH scavenging percentage was used to represent the antioxidant ability of RAMP. The maximum D value (0.328), along with the maximum yield (59.92%) and DPPH scavenging percentage (13.28%) were achieved at 90.54 min, 57.99 °C, 1.95% cellulase and 225.29 W. These values were further validated and found to be in good agreement with the predicted values. Compared to the other extraction methods, both the yield and scavenging percentage of RAMP obtained by UAEE was favorable and the method appeared to be time-saving and of high efficiency. These results demostrated that UAEE is an appropriate and effective extraction technique. Moreover, RSM with DF approach has been proved to be adequate for the design and optimization of the extraction parameters for RAMP. This work has a wide range of implications for the design and operation of polysaccharide extraction processes.

  8. Surface properties of functional polymer systems

    Science.gov (United States)

    Wong, Derek

    Polymer surface modification typically involves blending with other polymers or chemical modification of the parent polymer. Such strategies inevitably result in polymer systems that are spatially and chemically heterogeneous, and which exhibit the phenomenon of surface segregation. This work investigates the effects of chain architecture on the surface segregation behavior of such functionally modified polymers using a series of end- and center-fluorinated poly(D,L-lactide). Surface segregation of the fluorinated functional groups was observed in both chain architectures via AMPS and water contact angle. Higher surface segregation was noted for functional groups located at the chain end as opposed to those in the middle of the chain. A self-consistent mean-field lattice theory was used to model the composition depth profiles of functional groups and excellent agreement was found between the model predictions and the experimental AMPS data in both chain architectures. Polymer properties are also in general dependent on both time and temperature, and exhibit a range of relaxation times in response to environmental stimuli. This behavior arises from the characteristic frequencies of molecular motions of the polymer chain and the interrelationship between time and temperature has been widely established for polymer bulk properties. There is evidence that surface properties also respond in a manner that is time and temperature dependent and that this dependence may not be the same as that observed for bulk properties. AMPS and water contact angle experiments were used to investigate the surface reorganization behavior of functional groups using a series of anionically synthesized end-fluorinated and end-carboxylated poly(styrene). It was found that both types of functional end-groups reorganized upon a change in the polarity of the surface environment in order to minimize the surface free energy. ADXPS and contact angle results suggest that the reorganization depth was

  9. The nuclear response function

    International Nuclear Information System (INIS)

    Bertsch, G.F.

    1983-01-01

    These lectures present the theory of the nuclear response in the Random Phase Approximation (RPA). In the first lecture, various relations are derived between densities and currents which give rise to the well-known sum rules. Then RPA is derived via the time-dependent Hartree theory. The various formulations of RPA are shown: the configuration space representation, the coordinate space representation, the Landau theory of infinite systems and the RPA for separable interactions constrained by consistency. The remarkable success of RPA in describing the collective density oscillations of closed shell nuclei is illustrated with a few examples. In the final lecture, the σtau response is discussed with the application of simple theoretical considerations to the empirical data. Finally, we point out several problems which remain in the response theory. (author)

  10. Kernel regression with functional response

    OpenAIRE

    Ferraty, Frédéric; Laksaci, Ali; Tadj, Amel; Vieu, Philippe

    2011-01-01

    We consider kernel regression estimate when both the response variable and the explanatory one are functional. The rates of uniform almost complete convergence are stated as function of the small ball probability of the predictor and as function of the entropy of the set on which uniformity is obtained.

  11. Neisserial surface lipoproteins: structure, function and biogenesis.

    Science.gov (United States)

    Hooda, Yogesh; Shin, Hyejin E; Bateman, Thomas J; Moraes, Trevor F

    2017-03-01

    The surface of many Gram-negative bacteria contains lipidated protein molecules referred to as surface lipoproteins or SLPs. SLPs play critical roles in host immune evasion, nutrient acquisition and regulation of the bacterial stress response. The focus of this review is on the SLPs present in Neisseria, a genus of bacteria that colonise the mucosal surfaces of animals. Neisseria contains two pathogens of medical interest, namely Neisseria meningitidis and N. gonorrhoeae. Several SLPs have been identified in Neisseria and their study has elucidated key strategies used by these pathogens to survive inside the human body. Herein, we focus on the identification, structure and function of SLPs that have been identified in Neisseria. We also survey the translocation pathways used by these SLPs to reach the cell surface. Specifically, we elaborate on the strategies used by neisserial SLPs to translocate across the outer membrane with an emphasis on Slam, a novel outer membrane protein that has been implicated in SLP biogenesis. Taken together, the study of SLPs in Neisseria illustrates the widespread roles played by this family of proteins in Gram-negative bacteria. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Bioinspired surface functionalization of metallic biomaterials.

    Science.gov (United States)

    Su, Yingchao; Luo, Cheng; Zhang, Zhihui; Hermawan, Hendra; Zhu, Donghui; Huang, Jubin; Liang, Yunhong; Li, Guangyu; Ren, Luquan

    2018-01-01

    Metallic biomaterials are widely used for clinical applications because of their excellent mechanical properties and good durability. In order to provide essential biofunctionalities, surface functionalization is of particular interest and requirement in the development of high-performance metallic implants. Inspired by the functional surface of natural biological systems, many new designs and conceptions have recently emerged to create multifunctional surfaces with great potential for biomedical applications. This review firstly introduces the metallic biomaterials, important surface properties, and then elaborates some strategies on achieving the bioinspired surface functionalization for metallic biomaterials. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Generalized Response Surface Methodology : A New Metaheuristic

    NARCIS (Netherlands)

    Kleijnen, J.P.C.

    2006-01-01

    Generalized Response Surface Methodology (GRSM) is a novel general-purpose metaheuristic based on Box and Wilson.s Response Surface Methodology (RSM).Both GRSM and RSM estimate local gradients to search for the optimal solution.These gradients use local first-order polynomials.GRSM, however, uses

  14. Bioinspired Functional Surfaces for Technological Applications

    Science.gov (United States)

    Sharma, Vipul; Kumar, Suneel; Reddy, Kumbam Lingeshwar; Bahuguna, Ashish; Krishnan, Venkata

    2016-08-01

    Biological matters have been in continuous encounter with extreme environmental conditions leading to their evolution over millions of years. The fittest have survived through continuous evolution, an ongoing process. Biological surfaces are the important active interfaces between biological matters and the environment, and have been evolving over time to a higher state of intelligent functionality. Bioinspired surfaces with special functionalities have grabbed attention in materials research in the recent times. The microstructures and mechanisms behind these functional biological surfaces with interesting properties have inspired scientists to create artificial materials and surfaces which possess the properties equivalent to their counterparts. In this review, we have described the interplay between unique multiscale (micro- and nano-scale) structures of biological surfaces with intrinsic material properties which have inspired researchers to achieve the desired wettability and functionalities. Inspired by naturally occurring surfaces, researchers have designed and fabricated novel interfacial materials with versatile functionalities and wettability, such as superantiwetting surfaces (superhydrophobic and superoleophobic), omniphobic, switching wettability and water collecting surfaces. These strategies collectively enable functional surfaces to be utilized in different applications such as fog harvesting, surface-enhanced Raman spectroscopy (SERS), catalysis, sensing and biological applications. This paper delivers a critical review of such inspiring biological surfaces and artificial bioinspired surfaces utilized in different applications, where material science and engineering have merged by taking inspiration from the natural systems.

  15. Functionals of finite Riemann surfaces

    CERN Document Server

    Schiffer, Menahem

    1954-01-01

    This advanced monograph on finite Riemann surfaces, based on the authors' 1949-50 lectures at Princeton University, remains a fundamental book for graduate students. The Bulletin of the American Mathematical Society hailed the self-contained treatment as the source of ""a plethora of ideas, each interesting in its own right,"" noting that ""the patient reader will be richly rewarded."" Suitable for graduate-level courses, the text begins with three chapters that offer a development of the classical theory along historical lines, examining geometrical and physical considerations, existence theo

  16. Bio-inspired functional surfaces for advanced applications

    DEFF Research Database (Denmark)

    Malshe, Ajay; Rajurkar, Kamlakar; Samant, Anoop

    2013-01-01

    , are being evolved to a higher state of intelligent functionality. These surfaces became more efficient by using combinations of available materials, along with unique physical and chemical strategies. Noteworthy physical strategies include features such as texturing and structure, and chemical strategies...... such as sensing and actuation. These strategies collectively enable functional surfaces to deliver extraordinary adhesion, hydrophobicity, multispectral response, energy scavenging, thermal regulation, antibiofouling, and other advanced functions. Production industries have been intrigued with such biological...... surface strategies in order to learn clever surface architectures and implement those architectures to impart advanced functionalities into manufactured consumer products. This keynote paper delivers a critical review of such inspiring biological surfaces and their nonbiological product analogs, where...

  17. Functionalization of Block Copolymer Vesicle Surfaces

    Directory of Open Access Journals (Sweden)

    Wolfgang Meier

    2011-01-01

    Full Text Available In dilute aqueous solutions certain amphiphilic block copolymers self-assemble into vesicles that enclose a small pool of water with a membrane. Such polymersomes have promising applications ranging from targeted drug-delivery devices, to biosensors, and nanoreactors. Interactions between block copolymer membranes and their surroundings are important factors that determine their potential biomedical applications. Such interactions are influenced predominantly by the membrane surface. We review methods to functionalize block copolymer vesicle surfaces by chemical means with ligands such as antibodies, adhesion moieties, enzymes, carbohydrates and fluorophores. Furthermore, surface-functionalization can be achieved by self-assembly of polymers that carry ligands at their chain ends or in their hydrophilic blocks. While this review focuses on the strategies to functionalize vesicle surfaces, the applications realized by, and envisioned for, such functional polymersomes are also highlighted.

  18. Response function of a moving contact line

    Science.gov (United States)

    Perrin, H.; Belardinelli, D.; Sbragaglia, M.; Andreotti, B.

    2018-04-01

    The hydrodynamics of a liquid-vapor interface in contact with a heterogeneous surface is largely impacted by the presence of defects at the smaller scales. Such defects introduce morphological disturbances on the contact line and ultimately determine the force exerted on the wedge of liquid in contact with the surface. From the mathematical point of view, defects introduce perturbation modes, whose space-time evolution is governed by the interfacial hydrodynamic equations of the contact line. In this paper we derive the response function of the contact line to such generic perturbations. The contact line response may be used to design simplified one-dimensional time-dependent models accounting for the complexity of interfacial flows coupled to nanoscale defects, yet offering a more tractable mathematical framework to explore contact line motion through a disordered energy landscape.

  19. Functionalized silica nanoparticles as a carrier for Betamethasone Sodium Phosphate: Drug release study and statistical optimization of drug loading by response surface method.

    Science.gov (United States)

    Ghasemnejad, M; Ahmadi, E; Mohamadnia, Z; Doustgani, A; Hashemikia, S

    2015-11-01

    Mesoporous silica nanoparticles with a hexagonal structure (SBA-15) were synthesized and modified with (3-aminopropyl) triethoxysilane (APTES), and their performance as a carrier for drug delivery system was studied. Chemical structure and morphology of the synthesized and modified SBA-15 were characterized by SEM, BET, TEM, FT-IR and CHN technique. Betamethasone Sodium Phosphate (BSP) as a water soluble drug was loaded on the mesoporous silica particle for the first time. The response surface method was employed to obtain the optimum conditions for the drug/silica nanoparticle preparation, by using Design-Expert software. The effect of time, pH of preparative media, and drug/silica ratio on the drug loading efficiency was investigated by the software. The maximum loading (33.69%) was achieved under optimized condition (pH: 1.8, time: 3.54 (h) and drug/silica ratio: 1.7). The in vitro release behavior of drug loaded particles under various pH values was evaluated. Finally, the release kinetic of the drug was investigated using the Higuchi and Korsmeyer-Peppas models. Cell culture and cytotoxicity assays revealed the synthesized product doesn't have any cytotoxicity against human bladder cell line 5637. Accordingly, the produced drug-loaded nanostructures can be applied via different routes, such as implantation and topical or oral administration. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Separation and Determination of Honokiol and Magnolol in Chinese Traditional Medicines by Capillary Electrophoresis with the Application of Response Surface Methodology and Radial Basis Function Neural Network

    Science.gov (United States)

    Han, Ping; Luan, Feng; Yan, Xizu; Gao, Yuan; Liu, Huitao

    2012-01-01

    A method for the separation and determination of honokiol and magnolol in Magnolia officinalis and its medicinal preparation is developed by capillary zone electrophoresis and response surface methodology. The concentration of borate, content of organic modifier, and applied voltage are selected as variables. The optimized conditions (i.e., 16 mmol/L sodium tetraborate at pH 10.0, 11% methanol, applied voltage of 25 kV and UV detection at 210 nm) are obtained and successfully applied to the analysis of honokiol and magnolol in Magnolia officinalis and Huoxiang Zhengqi Liquid. Good separation is achieved within 6 min. The limits of detection are 1.67 µg/mL for honokiol and 0.83 µg/mL for magnolol, respectively. In addition, an artificial neural network with “3-7-1” structure based on the ratio of peak resolution to the migration time of the later component (Rs/t) given by Box-Behnken design is also reported, and the predicted results are in good agreement with the values given by the mathematic software and the experimental results. PMID:22291059

  1. Mechanisms regulating osteoblast response to surface microtopography and vitamin D

    Science.gov (United States)

    Bell, Bryan Frederick, Jr.

    A comprehensive understanding of the interactions between orthopaedic and dental implant surfaces with the surrounding host tissue is essential in the design of advanced biomaterials that better promote bone growth and osseointegration of implants. Dental implants with roughened surfaces and high surface energy are well known to promote osteoblast differentiation in vitro and promote increased bone-to-implant contact in vivo. In addition, increased surface roughness increases osteoblasts response to the vitamin D metabolite 1alpha,25(OH)2D3. However, the exact mechanisms mediating cell response to surface properties and 1alpha,25(OH)2D3 are still being elucidated. The central aim of the thesis is to investigate whether integrin signaling in response to rough surface microtopography enhances osteoblast differentiation and responsiveness to 1alpha,25(OH)2D3. The hypothesis is that the integrin alpha5beta1 plays a role in osteoblast response to surface microtopography and that 1alpha,25(OH) 2D3 acts through VDR-independent pathways involving caveolae to synergistically enhance osteoblast response to surface roughness and 1alpha,25(OH) 2D3. To test this hypothesis the objectives of the studies performed in this thesis were: (1) to determine if alpha5beta 1 signaling is required for osteoblast response to surface microstructure; (2) to determine if increased responsiveness to 1alpha,25(OH)2D 3 requires the vitamin D receptor, (3) to determine if rough titanium surfaces functionalized with the peptides targeting integrins (RGD) and transmembrane proteoglycans (KRSR) will enhance both osteoblast proliferation and differentiation, and (4) to determine whether caveolae, which are associated with integrin and 1alpha,25(OH)2D3 signaling, are required for enhance osteogenic response to surface microstructure and 1alpha,25(OH)2D 3. The results demonstrate that integrins, VDR, and caveolae play important roles in mediating osteoblast response to surface properties and 1alpha,25

  2. Surface plasma functionalization influences macrophage behavior on carbon nanowalls

    Energy Technology Data Exchange (ETDEWEB)

    Ion, Raluca [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Vizireanu, Sorin [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Stancu, Claudia Elena [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Luculescu, Catalin [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Cimpean, Anisoara, E-mail: anisoara.cimpean@bio.unibuc.ro [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Dinescu, Gheorghe [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania)

    2015-03-01

    The surfaces of carbon nanowall samples as scaffolds for tissue engineering applications were treated with oxygen or nitrogen plasma to improve their wettability and to functionalize their surfaces with different functional groups. X-ray photoelectron spectroscopy and water contact angle results illustrated the effective conversion of the carbon nanowall surfaces from hydrophobic to hydrophilic and the incorporation of various amounts of carbon, oxygen and nitrogen functional groups during the treatments. The early inflammatory responses elicited by un-treated and modified carbon nanowall surfaces were investigated by quantifying tumor necrosis factor-alpha and macrophage inflammatory protein-1 alpha released by attached RAW 264.7 macrophage cells. Scanning electron microscopy and fluorescence studies were employed to investigate the changes in macrophage morphology and adhesive properties, while MTT assay was used to quantify cell proliferation. All samples sustained macrophage adhesion and growth. In addition, nitrogen plasma treatment was more beneficial for cell adhesion in comparison with un-modified carbon nanowall surfaces. Instead, oxygen plasma functionalization led to increased macrophage adhesion and spreading suggesting a more activated phenotype, confirmed by elevated cytokine release. Thus, our findings showed that the chemical surface alterations which occur as a result of plasma treatment, independent of surface wettability, affect macrophage response in vitro. - Highlights: • N{sub 2} and O{sub 2} plasma treatments alter the CNW surface chemistry and wettability. • Cells seeded on CNW scaffolds are viable and metabolically active. • Surface functional groups, independent of surface wettability, affect cell response. • O{sub 2} plasma treatment of CNW leads to a more activated macrophage phenotype.

  3. Selective functionalization of patterned glass surfaces

    NARCIS (Netherlands)

    Ploetz, E.; Visser, B.; Slingenbergh, W.; Evers, K.; Martinez-Martinez, D.; Pei, Y. T.; Feringa, B. L.; De Hosson, J. Th. M.; Cordes, T.; van Dorp, W. F.

    2014-01-01

    Tailored writing and specific positioning of molecules on nanostructures is a key step for creating functional materials and nano-optical devices, or interfaces for synthetic machines in various applications. We present a novel approach for the selective functionalization of patterned glass surfaces

  4. Response Surface Methodology: 1966-1986

    Science.gov (United States)

    1986-09-01

    male broilers to examine quantitatively the protein levels in starter and Gnisher rations and the time of ration change to optimize body weight, carcass...1983). ’Akn Investigation of Protein Levels for Broiler Starter and Finisher Rations and the Time of Ration Change by Response Surface Methodology...when Responses Within a Litter are Correlated,’ Biometrics, 37, 153-156. Shek, E., Ghani, M. and Jones, R.E. (1980). "Simplex Search in Optimization

  5. THE KEPLER PIXEL RESPONSE FUNCTION

    International Nuclear Information System (INIS)

    Bryson, Stephen T.; Haas, Michael R.; Dotson, Jessie L.; Koch, David G.; Borucki, William J.; Tenenbaum, Peter; Jenkins, Jon M.; Chandrasekaran, Hema; Caldwell, Douglas A.; Klaus, Todd; Gilliland, Ronald L.

    2010-01-01

    Kepler seeks to detect sequences of transits of Earth-size exoplanets orbiting solar-like stars. Such transit signals are on the order of 100 ppm. The high photometric precision demanded by Kepler requires detailed knowledge of how the Kepler pixels respond to starlight during a nominal observation. This information is provided by the Kepler pixel response function (PRF), defined as the composite of Kepler's optical point-spread function, integrated spacecraft pointing jitter during a nominal cadence and other systematic effects. To provide sub-pixel resolution, the PRF is represented as a piecewise-continuous polynomial on a sub-pixel mesh. This continuous representation allows the prediction of a star's flux value on any pixel given the star's pixel position. The advantages and difficulties of this polynomial representation are discussed, including characterization of spatial variation in the PRF and the smoothing of discontinuities between sub-pixel polynomial patches. On-orbit super-resolution measurements of the PRF across the Kepler field of view are described. Two uses of the PRF are presented: the selection of pixels for each star that maximizes the photometric signal-to-noise ratio for that star, and PRF-fitted centroids which provide robust and accurate stellar positions on the CCD, primarily used for attitude and plate scale tracking. Good knowledge of the PRF has been a critical component for the successful collection of high-precision photometry by Kepler.

  6. Pavement Aging Model by Response Surface Modeling

    Directory of Open Access Journals (Sweden)

    Manzano-Ramírez A.

    2011-10-01

    Full Text Available In this work, surface course aging was modeled by Response Surface Methodology (RSM. The Marshall specimens were placed in a conventional oven for time and temperature conditions established on the basis of the environment factors of the region where the surface course is constructed by AC-20 from the Ing. Antonio M. Amor refinery. Volatilized material (VM, load resistance increment (ΔL and flow resistance increment (ΔF models were developed by the RSM. Cylindrical specimens with real aging were extracted from the surface course pilot to evaluate the error of the models. The VM model was adequate, in contrast (ΔL and (ΔF models were almost adequate with an error of 20 %, that was associated with the other environmental factors, which were not considered at the beginning of the research.

  7. Stem cell responses to plasma surface modified electrospun polyurethane scaffolds.

    Science.gov (United States)

    Zandén, Carl; Hellström Erkenstam, Nina; Padel, Thomas; Wittgenstein, Julia; Liu, Johan; Kuhn, H Georg

    2014-07-01

    The topographical effects from functional materials on stem cell behavior are currently of interest in tissue engineering and regenerative medicine. Here we investigate the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell (hESC) and rat postnatal neural stem cell (NSC) responses. The plasma gases were found to induce three combinations of fiber surface functionalities and roughness textures. On randomly oriented fibers, plasma treatments lead to substantially increased hESC attachment and proliferation as compared to native fibers. Argon plasma was found to induce the most optimal combination of surface functionality and roughness for cell expansion. Contact guided migration of cells and alignment of cell processes were observed on aligned fibers. Neuronal differentiation around 5% was found for all samples and was not significantly affected by the induced variations of surface functional group distribution or individual fiber topography. In this study the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell and rat postnatal neural stem cell (NSC) responses is studied with the goal of clarifying the potential effects of functional materials on stem cell behavior, a topic of substantial interest in tissue engineering and regenerative medicine. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Linear density response function in the projector augmented wave method

    DEFF Research Database (Denmark)

    Yan, Jun; Mortensen, Jens Jørgen; Jacobsen, Karsten Wedel

    2011-01-01

    We present an implementation of the linear density response function within the projector-augmented wave method with applications to the linear optical and dielectric properties of both solids, surfaces, and interfaces. The response function is represented in plane waves while the single...... functions of Si, C, SiC, AlP, and GaAs compare well with previous calculations. While optical properties of semiconductors, in particular excitonic effects, are generally not well described by ALDA, we obtain excellent agreement with experiments for the surface loss function of graphene and the Mg(0001...

  9. Functional dynamics of cell surface membrane proteins.

    Science.gov (United States)

    Nishida, Noritaka; Osawa, Masanori; Takeuchi, Koh; Imai, Shunsuke; Stampoulis, Pavlos; Kofuku, Yutaka; Ueda, Takumi; Shimada, Ichio

    2014-04-01

    Cell surface receptors are integral membrane proteins that receive external stimuli, and transmit signals across plasma membranes. In the conventional view of receptor activation, ligand binding to the extracellular side of the receptor induces conformational changes, which convert the structure of the receptor into an active conformation. However, recent NMR studies of cell surface membrane proteins have revealed that their structures are more dynamic than previously envisioned, and they fluctuate between multiple conformations in an equilibrium on various timescales. In addition, NMR analyses, along with biochemical and cell biological experiments indicated that such dynamical properties are critical for the proper functions of the receptors. In this review, we will describe several NMR studies that revealed direct linkage between the structural dynamics and the functions of the cell surface membrane proteins, such as G-protein coupled receptors (GPCRs), ion channels, membrane transporters, and cell adhesion molecules. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. TOPICAL REVIEW: Vicinal surfaces for functional nanostructures

    Science.gov (United States)

    Tegenkamp, Christoph

    2009-01-01

    Vicinal surfaces are currently the focus of research. The regular arrangements of atomic steps on a mesoscopic scale reveal the possibility to functionalize these surfaces for technical applications, e.g. nanowires, catalysts, etc. The steps of the vicinal surface are well-defined defect structures of atomic size for nucleation of low-dimensional nanostructures. The concentration and therefore the coupling between the nanostructures can be tuned over a wide range by simply changing the inclination angle of the substrate. However, the coupling of these nano-objects to the substrate is just as important in controlling their electronic or chemical properties and making a functionality useable. On the basis of stepped insulating films, these aspects are fulfilled and will be considered in the first part of this review. Recent results for the epitaxial growth of wide bandgap insulating films (CaF2, MgO, NaCl, BaSrO) on metallic and semiconducting vicinal substrates (Si(100), Ge(100), Ag(100)) will be presented. The change of the electronic structure, the adsorption behavior as well as the kinetics and energetics of color centers in the presence of steps is discussed. The successful bridging of the gap between the atomic and mesoscopic world, i.e. the functionalization of vicinal surfaces by nanostructures, is demonstrated in the second part by metal adsorption on semiconducting surfaces. For (sub)monolayer coverage these systems have in common that the surface states do not hybridize with the support, i.e. the semiconducting surfaces are insulating. Here I will focus on the latest results of macroscopic transport measurements on Pb quantum wires grown on vicinal Si(111) showing indeed a one-dimensional transport behavior.

  11. SURFACE TEXTURE ANALYSIS FOR FUNCTIONALITY CONTROL

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Andreasen, Jan Lasson; Tosello, Guido

    This document is used in connection with three exercises of 3 hours duration as a part of the course VISION ONLINE – One week course on Precision & Nanometrology. The exercises concern surface texture analysis for functionality control, in connection with three different case stories. This docume...... contains a short description of each case story, 3-D roughness parameters analysis and relation with the product’s functionality.......This document is used in connection with three exercises of 3 hours duration as a part of the course VISION ONLINE – One week course on Precision & Nanometrology. The exercises concern surface texture analysis for functionality control, in connection with three different case stories. This document...

  12. Dielectric response functions of the (000-1), (10-13) GaN single crystalline and disordered surfaces studied by reflection electron energy loss spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Romanyuk, Olexandr; Jiříček, Petr; Zemek, Josef; Tougaard, S.; Paskova, T.

    2011-01-01

    Roč. 110, č. 4 (2011), 043507/1-043507/7 ISSN 0021-8979 R&D Projects: GA ČR GPP204/10/P028 Grant - others:MDA(US) HQ0147-09-C-0005 Institutional research plan: CEZ:AV0Z10100521 Keywords : GaN * REELS * optical constants * semiconductor surfaces Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.168, year: 2011

  13. Permanent isolation surface barrier: Functional performance

    International Nuclear Information System (INIS)

    Wing, N.R.

    1993-10-01

    This document presents the functional performance parameters for permanent isolation surface barriers. Permanent isolation surface barriers have been proposed for use at the Hanford Site (and elsewhere) to isolate and dispose of certain types of waste in place. Much of the waste that would be disposed of using in-place isolation techniques is located in subsurface structures, such as solid waste burial grounds, tanks, vaults, and cribs. Unless protected in some way, the wastes could be transported to the accessible environment via transport pathways, such as water infiltration, biointrusion, wind and water erosion, human interference, and/or gaseous release

  14. Surface functionalization of dopamine coated iron oxide nanoparticles for various surface functionalities

    Energy Technology Data Exchange (ETDEWEB)

    Sherwood, Jennifer; Xu, Yaolin; Lovas, Kira [Chemical and Biological Engineering, The University of Alabama, Tuscaloosa , AL 35487 (United States); Qin, Ying [Alabama Innovation and Mentoring of Entrepreneurs, The University of Alabama, Tuscaloosa, AL 35487 (United States); Bao, Yuping, E-mail: ybao@eng.ua.edu [Chemical and Biological Engineering, The University of Alabama, Tuscaloosa , AL 35487 (United States)

    2017-04-01

    We present effective conjugation of four small molecules (glutathione, cysteine, lysine, and Tris(hydroxymethyl)aminomethane) onto dopamine-coated iron oxide nanoparticles. Conjugation of these molecules could improve the surface functionality of nanoparticles for more neutral surface charge at physiological pH and potentially reduce non-specific adsorption of proteins to nanoparticles surfaces. The success of conjugation was evaluated with dynamic light scattering by measuring the surface charge changes and Fourier transform infrared spectroscopy for surface chemistry analysis. The stability of dopamine-coated nanoparticles and the ability of conjugated nanoparticles to reduce the formation of protein corona were evaluated by measuring the size and charge of the nanoparticles in biological medium. This facile conjugation method opens up possibilities for attaching various surface functionalities onto iron oxide nanoparticle surfaces for biomedical applications.

  15. Surface functionalization of dopamine coated iron oxide nanoparticles for various surface functionalities

    International Nuclear Information System (INIS)

    Sherwood, Jennifer; Xu, Yaolin; Lovas, Kira; Qin, Ying; Bao, Yuping

    2017-01-01

    We present effective conjugation of four small molecules (glutathione, cysteine, lysine, and Tris(hydroxymethyl)aminomethane) onto dopamine-coated iron oxide nanoparticles. Conjugation of these molecules could improve the surface functionality of nanoparticles for more neutral surface charge at physiological pH and potentially reduce non-specific adsorption of proteins to nanoparticles surfaces. The success of conjugation was evaluated with dynamic light scattering by measuring the surface charge changes and Fourier transform infrared spectroscopy for surface chemistry analysis. The stability of dopamine-coated nanoparticles and the ability of conjugated nanoparticles to reduce the formation of protein corona were evaluated by measuring the size and charge of the nanoparticles in biological medium. This facile conjugation method opens up possibilities for attaching various surface functionalities onto iron oxide nanoparticle surfaces for biomedical applications.

  16. Functionalization and Polymerization on the CNT Surfaces

    KAUST Repository

    Albuerne, Julio

    2013-07-01

    In this review we focus on the current status of using carbon nanotube (CNT) as a filler for polymer nanocomposites. Starting with the historical background of CNT, its distinct properties and the surface functionalization of the nanotube, the three different surface polymerization techniques, namely grafting "from", "to" and "through/in between" were discussed. Wider focus has been given on "grafting from" surface initiated polymerizations, including atom transfer radical polymerization (ATRP), reversible addition fragmentation chain-transfer (RAFT) Polymerization, nitroxide mediated polymerization (NMP), ring opening polymerization (ROP) and other miscellaneous polymerization methods. The grafting "to" and "through / in between" also discussed and compared with grafting from polymerization. The merits and shortcomings of all three grafting methods were discussed and the bottleneck issue in grafting from method has been highlighted. Furthermore the current and potential future industrial applications were deliberated. Finally the toxicity issue of CNTs in the final product has been reviewed with the limited available literature knowledge. © 2013 Bentham Science Publishers.

  17. Autoimmune Response Confers Decreased Cardiac Function in ...

    African Journals Online (AJOL)

    inflammatory response; rather, autoimmune response would keep affecting decreased heart function in. RHD patients who ... untreated children. Nearly 30 - 45 % of the affected children could ..... Technology Department of Anhui Province (PR.

  18. Femtosecond tunneling response of surface plasmon polaritons

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Ha, Taekjip; Jensen, Jacob Riis

    1998-01-01

    We obtain femtosecond (200 fs) time resolution using a scanning tunneling microscope on surface plasmon polaritons (SPPs) generated by two 100 fs laser beams in total internal reflection geometry. The tunneling gap dependence of the signal clearly indicates the tunneling origin of the signal...... and suggests that nanometer spatial resolution can be obtained together with femtosecond temporal resolution. This fast response, in contrast to the picosecond decay time of SPPs revealed by differential reflectivity measurements, can be attributed to a coherent superposition of SPPs rectified at the tunneling...

  19. Preparation, characterization, uranium (VI) biosorption models, and conditions optimization by response surface methodology (RSM) for amidoxime-functionalized marine fungus materials

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xuechun; Gao, Yang; Jiang, Min; He, Dianxiong; Liao, Sen; Hou, Dan; Yan, Xueming; Long, Wei; Wu, Yaxin; Tan, Ni [Univ. of South China, Hengyang (China). School of Chemistry and Chemical Engineering

    2017-08-01

    Amidoxime-functionalized marine fungus Fusarium sp. ZZF51 (ZGDA) was synthesized and studied to adsorb uranium (VI) from the aqueous solution. Different instrumental techniques such as FTIR, SEM, and TGA were employed for the characterization of the manufactured materials, and theirs ability of removal uranium (VI) was optimized using RSM. The experimental results showed the maximum adsorption capacity for the synthesized materials was 230.78 mg g{sup -1} at the following optimization conditions: S-L ratio 150 mg L{sup -1}, pH 5.13, uranium (VI) initial concentration 40 mg L{sup -1}, and equilibrium time 122.40 min. More than 85% of the absorbed uranium (VI) could be desorbed by 0.5 or 1.0 mol L{sup -1} HCl, and the modified mycelium could be reused at least five times. The thermodynamic experimental data of adsorption uranium (VI) could fit better with Langmuir and Freundlich isotherms models, and the pseudo-second-order model was better to interpret the kinetics process. The modified fungus materials exhibited the better sorption capacity for uranium (VI) in comparison with raw biomass should be attributed to the strong chelation of amidoxime to uranium (VI) ions.

  20. Surface structure of polymer Gels and emerging functions

    CERN Document Server

    Kobiki, Y

    1999-01-01

    We report the surface structure of polymer gels on a submicrometer scale during the volume phase transition. Sponge-like domains with a mesoscopic scale were directly observed in water by using at atomic force microscope (AFM). The surface structure characterized by the domains is discussed in terms of the root-mean-square roughness and the auto-correlation function, which were calculated from the AFM images. In order to demonstrate the role of surface structure in determining the macroscopic properties of film-like poly (N-isopropylacrylamide: NIPA) gels. It was found that the temperature dependence, as well as the absolute values of the static contact angle, were strongly dependent on the bulk network inhomogeneities. The relation between the mesoscopic structure and the macroscopic properties is qualitatively discussed in terms of not only the changes in the chemical, but also in the physical, surface properties of the NIPA gels in response to a temperature change.

  1. Electron work function of stepped tungsten surfaces

    International Nuclear Information System (INIS)

    Krahl-Urban, B.

    1976-03-01

    The electron work function of tungsten (110) vicinal faces was measured with the aid of thermionic emission, and its dependence on the crystallographic orientation and the surface structure was investigated. The thermionic measurements were evaluated with the aid of the Richardson plot. The real temperature of the emitting tungsten faces was determined with an accuracy of +- 0.5% in the range between 2,200 and 2,800 K. The vicinal faces under investigation have been prepared with an orientation exactness of +- 15'. In the tungsten (110) vicinal faces under investigation, a strong dependence of the temperature coefficient d PHI/dT of the work function on the crystallographic orientation was found. A strong influence of the edge structure as well as of the step density on the temperature coefficient was observed. (orig./HPOE) [de

  2. ARES: automated response function code. Users manual

    International Nuclear Information System (INIS)

    Maung, T.; Reynolds, G.M.

    1981-06-01

    This ARES user's manual provides detailed instructions for a general understanding of the Automated Response Function Code and gives step by step instructions for using the complete code package on a HP-1000 system. This code is designed to calculate response functions of NaI gamma-ray detectors, with cylindrical or rectangular geometries

  3. Application of Response Surface Methodology for Optimizing Oil ...

    African Journals Online (AJOL)

    Application of Response Surface Methodology for Optimizing Oil Extraction Yield From ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search ... from tropical almond seed by the use of response surface methodology (RSM).

  4. Selection of a design for response surface

    Science.gov (United States)

    Ranade, Shruti Sunil; Thiagarajan, Padma

    2017-11-01

    Box-Behnken, Central-Composite, D and I-optimal designs were compared using statistical tools. Experimental trials for all designs were generated. Random uniform responses were simulated for all models. R-square, Akaike and Bayesian Information Criterion for the fitted models were noted. One-way ANOVA and Tukey’s multiple comparison test were performed on these parameters. These models were evaluated based on the number of experimental trials generated in addition to the results of the statistical analyses. D-optimal design generated 12 trials in its model, which was lesser in comparison to both Central Composite and Box-Behnken designs. The R-square values of the fitted models were found to possess a statistically significant difference (P<0.0001). D-optimal design not only had the highest mean R-square value (0.7231), but also possessed the lowest means for both Akaike and Bayesian Information Criterion. The D-optimal design was recommended for generation of response surfaces, based on the assessment of the above parameters.

  5. Sum rules in the response function method

    International Nuclear Information System (INIS)

    Takayanagi, Kazuo

    1990-01-01

    Sum rules in the response function method are studied in detail. A sum rule can be obtained theoretically by integrating the imaginary part of the response function over the excitation energy with a corresponding energy weight. Generally, the response function is calculated perturbatively in terms of the residual interaction, and the expansion can be described by diagrammatic methods. In this paper, we present a classification of the diagrams so as to clarify which diagram has what contribution to which sum rule. This will allow us to get insight into the contributions to the sum rules of all the processes expressed by Goldstone diagrams. (orig.)

  6. Ellipsometry of functional organic surfaces and films

    CERN Document Server

    Eichhorn, Klaus-Jochen

    2018-01-01

    This new edition provides a state-of-the-art survey of ellipsometric methods used to study organic films and surfaces, from laboratory to synchrotron applications, with a special focus on in-situ use in processing environments and at solid-liquid interfaces. Thanks to the development of functional organic, meta- and hybrid materials for new optical, electronic, sensing and biotechnological devices, the ellipsometric analysis of optical and material properties has made tremendous strides over the past few years. The second edition has been updated to reflect the latest advances in ellipsometric methods. The new content focuses on the study of anisotropic materials, conjugated polymers, polarons, self-assembled monolayers, industrial membranes, adsorption of proteins, enzymes and RGD-peptides, as well as the correlation of ellipsometric spectra to structure and molecular interactions.

  7. Functional anatomy and immunological interactions of ocular surface and adnexa.

    Science.gov (United States)

    Paulsen, Friedrich

    2008-01-01

    This chapter gives an overview about the structures and physiology of the ocular surface and its adnexa and focuses in a second part on the possible meaning of eye-associated lymphoid tissue (EALT) in a context with the development of dry eye. Sections deal with (1) anatomy of the ocular surface, lacrimal gland, eyelid and nasolacrimal ducts. (2) The meaning and importance of the lacrimal functional unit and the function of the mucosal innate immune system are briefly summarized. (3) Finally, the occurrence and the possible function of EALT is discussed with regard to tolerance induction and dry eye. The epithelial surface of the eye and its specialized glandular infoldings produce the components of the tear film, which include water, protective antimicrobials, cytokines, lipids as well as mucins and trefoil factor family (TFF) peptides. Antimicrobials, mucins and TFF peptides perform a number of essential functions which, collectively, provide protection of the ocular surface. Their production changes in cases of dry eye. The development of EALT is a common feature frequently occurring in symptomatically normal conjunctiva and nasolacrimal ducts. The production of antimicrobials, mucins and TFF peptides can be linked with cell signaling, tear film rheology, and antimicrobial defense at the ocular surface. Changes in the production of such peptides and proteins in cases of dry eye support the assumption that these peptides and proteins are involved in the pathophysiological events that occur at the ocular surface and lacrimal apparatus. Whether special types of bacteria, viruses, or other factors, e.g., immune deviation, are responsible for the development of EALT in humans requires further investigation in prospective and experimental studies.

  8. PREFACE Surface Modifications and Functionalization of Materials for Biomedical Applications

    Science.gov (United States)

    Endrino, Jose Luis; Puértolas, Jose A.; Albella, Jose M.

    2010-11-01

    Conference photograph This special issue contains selected papers which were presented as invited and contributed communications at the workshop entitled 'Surface modification and functionalization of materials for biomedical applications' (BIO-COAT 2010) which was held on 24 June 2010 in Zaragoza (Spain). The surface of a material plays a major role in its interaction with the biological medium. Processes related to the mechanical stability of articular devices in contact, osseointegration, thrombogenicity, corrosion and leaching, or the inflammatory response of rejection of a material, are clearly conditioned by the surface properties. Therefore, the modification or functionalization of surfaces can have an important impact on these issues. New techniques for functionalization by thin film deposition or surface treatments help to improve superficial properties, while understanding the interaction of the surface-biological medium is critical for their application in new devices. Jointly organized by the Spanish Materials Research Society, BIO-COAT 2010 provided an open forum to discuss the progress and latest developments in thin film processing and the engineering of biomaterials. Invited lectures were particularly aimed at providing overviews on scientific topics and were given by recognized world-class scientists. Two of them have contributed with a proceedings article to this selected collection (articles 012001 and 012008). The contributed communications were focused on particular cutting-edge aspects of thin film science and functionalization technologies for biomaterials, showing the major scientific push of Spanish research groups in the field. The 2010 BIO-COAT conference was organized along four main topics: (1) functionalization and texture on surfaces, (2) tribology and corrosion, (3) the surface modification of biomaterials, and (4) surface-biological environment interactions. The papers published in this volume were accepted for publication after

  9. A wireless wearable surface functional electrical stimulator

    Science.gov (United States)

    Wang, Hai-Peng; Guo, Ai-Wen; Zhou, Yu-Xuan; Xia, Yang; Huang, Jia; Xu, Chong-Yao; Huang, Zong-Hao; Lü, Xiao-Ying; Wang, Zhi-Gong

    2017-09-01

    In this paper, a wireless wearable functional electrical stimulator controlled by Android phone with real-time-varying stimulation parameters for multichannel surface functional electrical stimulation application has been developed. It can help post-stroke patients using more conveniently. This study focuses on the prototype design, including the specific wristband concept, circuits and stimulation pulse-generation algorithm. A novel stimulator circuit with a driving stage using a complementary current source technique is proposed to achieve a high-voltage compliance, a large output impedance and an accurate linear voltage-to-current conversion. The size of the prototype has been significantly decreased to 17 × 7.5 × 1 cm3. The performance of the prototype has been tested with a loaded resistor and wrist extension/flexion movement of three hemiplegic patients. According to the experiments, the stimulator can generate four-channel charge-balanced biphasic stimulation with a voltage amplitude up to 60 V, and the pulse frequency and width can be adjusted in real time with a range of 100-600 μs and 20-80 Hz, respectively.

  10. Switchable and responsive surfaces and materials for biomedical applications

    CERN Document Server

    Zhang, Johnathan

    2015-01-01

    Surface modification of biomaterials can ultimately determine whether a material is accepted or rejected from the human body, and a responsive surface can further make the material ""smart"" and ""intelligent"". Switchable and Responsive Surfaces and Materials for Biomedical Applications outlines synthetic and biological materials that are responsive under different stimuli, their surface design and modification techniques, and applicability in regenerative medicine/tissue engineering,  drug delivery, medical devices, and biomedical diagnostics. Part one provides a detailed overview of swit

  11. Polyester textile functionalization through incorporation of pH/thermo-responsive microgels. Part II: polyester functionalization and characterization

    NARCIS (Netherlands)

    Glampedaki, P.; Calvimontes, A.; Dutschk, Victoria; Warmoeskerken, Marinus

    2012-01-01

    A new approach to functionalize the surface of polyester textiles is described in this study. Functionalization was achieved by incorporating pH/temperature-responsive polyelectrolyte microgels into the textile surface layer using UV irradiation. The aim of functionalization was to regulate

  12. Coping responses as predictors of psychosocial functioning ...

    African Journals Online (AJOL)

    ... West Haven-Yale Multidimensional Pain Inventory and the Coping Responses Inventory – Adult Form. The prevalence of the use of Avoidance and Approach Coping, and the relationship between these responses and psychosocial functioning (Pain Severity, Interference, Support, Life Control, and Affective Distress) were ...

  13. Effect of surface roughness and surface modification of indium tin oxide electrode on its potential response to tryptophan

    International Nuclear Information System (INIS)

    Khan, Md. Zaved Hossain; Nakanishi, Takuya; Kuroiwa, Shigeki; Hoshi, Yoichi; Osaka, Tetsuya

    2011-01-01

    Highlights: → We examine factors affecting potential response of ITO electrode to tryptophan. → Surface roughness of ITO electrode affects the stability of its rest potential. → Surface modification is effective for ITO electrode with a certain roughness. → Optimum values of work function exist for potential response of ITO to tryptophan. - Abstract: The effect of surface modification of indium tin oxide (ITO) electrode on its potential response to tryptophan was investigated for ITO substrates with different surface roughness. It was found that a small difference in surface roughness, between ∼1 and ∼2 nm of R a evaluated by atomic force microscopy, affects the rest potential of ITO electrode in the electrolyte. A slight difference in In:Sn ratio at the near surface of the ITO substrates, measured by angle-resolved X-ray photoelectron spectrometry and Auger electron spectroscopy is remarkable, and considered to relate with surface roughness. Interestingly, successive modification of the ITO surface with aminopropylsilane and disuccinimidyl suberate, of which essentiality to the potential response to indole compounds we previously reported, improved the stability of the rest potential and enabled the electrodes to respond to tryptophan in case of specimens with R a values ranging between ∼2 and ∼3 nm but not for those with R a of ∼1 nm. It was suggested that there are optimum values of effective work function of ITO for specific potential response to tryptophan, which can be obtained by the successive modification of ITO surface.

  14. AGE STRUCTURE OR FUNCTIONAL RESPONSE? RECONCILING ...

    African Journals Online (AJOL)

    ... surplus production that differ from traditional single-species management models. ... Specifically, while the ECOSIM “Arena” functional response and the von ... as a proxy for age structure rather than as a function of predator/prey behaviour, ...

  15. Chief Business Officers' Functions: Responsibilities and Importance.

    Science.gov (United States)

    Calver, Richard A.; Vogler, Daniel E.

    1985-01-01

    Reports on a survey of 177 chief business officers of public community colleges regarding their responsibilities and the importance they assigned to various role functions. Highlights findings concerning the perceived importance of fiscal/financial duties; endowments as a job function; role in shared planning; and personal attention given to…

  16. Semiclassical theory for the nuclear response function

    International Nuclear Information System (INIS)

    Stroth, U.

    1986-01-01

    In the first part of this thesis it was demonstrated how on a semiclassical base a RPA theory is developed and applied to electron scattering. It was shown in which fields of nuclear physics this semiclassical theory can be applied and how it is to be understood. In this connection we dedicated an extensive discussion to the Fermi gas model. From the free response function we calculated the RPA response with a finite-range residual interaction which we completely antisymmetrize. In the second part of this thesis we studied with our theory (e,e') data for the separated response functions. (orig./HSI) [de

  17. Nonlocal surface plasmons by Poisson Green's function matching

    International Nuclear Information System (INIS)

    Morgenstern Horing, Norman J

    2006-01-01

    The Poisson Green's function for all space is derived for the case in which an interface divides space into two separate semi-infinite media, using the Green's function matching method. Each of the separate semi-infinite constituent parts has its own dynamic, nonlocal polarizability, which is taken to be unaffected by the presence of the interface and is represented by the corresponding bulk response property. While this eliminates Friedel oscillatory phenomenology near the interface with p ∼ 2p F , it is nevertheless quite reasonable and useful for a broad range of lower (nonvanishing) wavenumbers, p F . The resulting full-space Poisson Green's function is dynamic, nonlocal and spatially inhomogeneous, and its frequency pole yields the surface plasmon dispersion relation, replete with dynamic and nonlocal features. It also accommodates an ambient magnetic field

  18. Radiological emergency response - a functional approach

    International Nuclear Information System (INIS)

    Chowdhury, P.

    1998-01-01

    The state of Louisiana's radiological emergency response programme is based on the federal guidance 'Criteria for Preparation and Evaluation of Radiological Emergency Response Plans and Preparedness in Support of Nuclear Power Plants' (NUREG-0654, FEMA-REP-1 Rev. 1). Over the past 14 years, the planning and implementation of response capabilities became more organized and efficient; the training programme has strengthened considerably; co-ordination with all participating agencies has assumed a more co-operative role, and as a result, a fairly well integrated response planning has evolved. Recently, a more 'functional' approach is being adopted to maximize the programme's efficiency not only for nuclear power plant emergency response, but radiological emergency response as a whole. First, several broad-based 'components' are identified; clusters of 'nodes' are generated for each component; these 'nodes' may be divided into 'sub-nodes' which will contain some 'attributes'; 'relational bonds' among the 'attributes' will exist. When executed, the process begins and continues with the 'nodes' assuming a functional and dynamic role based on the nature and characteristics of the 'attributes'. The typical response based on stand-alone elements is thus eliminated, the overlapping of functions is avoided, and a well structured and efficient organization is produced, that is essential for today's complex nature of emergency response. (author)

  19. A simple approach for the sonochemical loading of Au, Ag and Pd nanoparticle on functionalized MWCNT and subsequent dispersion studies for removal of organic dyes: Artificial neural network and response surface methodology studies.

    Science.gov (United States)

    Moghaddari, Mitra; Yousefi, Fakhri; Ghaedi, Mehrorang; Dashtian, Kheibar

    2018-04-01

    In this study, the artificial neural network (ANN) and response surface methodology (RSM) based on central composite design (CCD) were applied for modeling and optimization of the simultaneous ultrasound-assisted removal of quinoline yellow (QY) and eosin B (EB). The MWCNT-NH 2 and its composites were prepared by sonochemistry method and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analysis's. Initial dyes concentrations, adsorbent mass, sonication time and pH contribution on QY and EB removal percentage were investigated by CCD and replication of experiments at conditions suggested by model has results which statistically are close to experimented data. The ultrasound irradiation is associated with raising mass transfer of process so that small amount of the adsorbent (0.025 g) is able to remove high percentage (88.00% and 91.00%) of QY and EB, respectively in short time (6.0 min) at pH = 6. Analysis of experimental data by conventional models is good indication of Langmuir efficiency for fitting and explanation of experimented data. The ANN based on the Levenberg-Marquardt algorithm (LMA) combined of linear transfer function at output layer and tangent sigmoid transfer function at hidden layer with 20 hidden neurons supply best operation conditions for good prediction of adsorption data. Accurate and efficient artificial neural network was obtained by changing the number of neurons in the hidden layer, while data was divided into training, test and validation sets which contained 70, 15 and 15% of data points respectively. The Average absolute deviation (AAD)% of a collection of 128 data points for MWCNT-NH 2 and composites is 0.58%.for EB and 0.55 for YQ. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Response Surface Optimized Extraction of Total Triterpene Acids ...

    African Journals Online (AJOL)

    Tropical Journal of Pharmaceutical Research May 2014; 13 (5): 787-792 ... surface method were used to optimize the extraction process, while antioxidant activity was evaluated in vitro using α ... Response surface methodology is increasingly.

  1. Kramers-Kronig transform for the surface energy loss function

    International Nuclear Information System (INIS)

    Tan, G.L.; DeNoyer, L.K.; French, R.H.; Guittet, M.J.; Gautier-Soyer, M.

    2005-01-01

    A new pair of Kramers-Kronig (KK) dispersion relationships for the transformation of surface energy loss function Im[-1/(ε + 1)] has been proposed. The validity of the new surface KK transform is confirmed, using both a Lorentz oscillator model and the surface energy loss functions determined from the experimental complex dielectric function of SrTiO 3 and tungsten metal. The interband transition strength spectra (J cv ) have been derived either directly from the original complex dielectric function or from the derived dielectric function obtained from the KK transform of the surface energy loss function. The original J cv trace and post-J cv trace overlapped together for the three modes, indicating that the new surface Kramers-Kronig dispersion relationship is valid for the surface energy loss function

  2. Diagnostics for Linear Models With Functional Responses

    OpenAIRE

    Xu, Hongquan; Shen, Qing

    2005-01-01

    Linear models where the response is a function and the predictors are vectors are useful in analyzing data from designed experiments and other situations with functional observations. Residual analysis and diagnostics are considered for such models. Studentized residuals are defined and their properties are studied. Chi-square quantile-quantile plots are proposed to check the assumption of Gaussian error process and outliers. Jackknife residuals and an associated test are proposed to det...

  3. Response of human corneal fibroblasts on silk film surface patterns.

    Science.gov (United States)

    Gil, Eun Seok; Park, Sang-Hyug; Marchant, Jeff; Omenetto, Fiorenzo; Kaplan, David L

    2010-06-11

    Transparent, biodegradable, mechanically robust, and surface-patterned silk films were evaluated for the effect of surface morphology on human corneal fibroblast (hCF) cell proliferation, orientation, and ECM deposition and alignment. A series of dimensionally different surface groove patterns were prepared from optically graded glass substrates followed by casting poly(dimethylsiloxane) (PDMS) replica molds. The features on the patterned silk films showed an array of asymmetric triangles and displayed 37-342 nm depths and 445-3 582 nm widths. hCF DNA content on all patterned films were not significantly different from that on flat silk films after 4 d in culture. However, the depth and width of the grooves influenced cell alignment, while the depth differences affected cell orientation; overall, deeper and narrower grooves induced more hCF orientation. Over 14 d in culture, cell layers and actin filament organization demonstrated that confluent hCFs and their cytoskeletal filaments were oriented along the direction of the silk film patterned groove axis. Collagen type V and proteoglycans (decorin and biglycan), important markers of corneal stromal tissue, were highly expressed with alignment. Understanding corneal stromal fibroblast responses to surface features on a protein-based biomaterial applicable in vivo for corneal repair potential suggests options to improve corneal tissue mimics. Further, the approaches provide fundamental biomaterial designs useful for bioengineering oriented tissue layers, an endemic feature in most biological tissue structures that lead to critical tissue functions.

  4. Interaction between Palladium Nanoparticles and Surface-Modified Carbon Nanotubes: Role of Surface Functionalities

    DEFF Research Database (Denmark)

    Zhang, Bingsen; Shao, Lidong; Zhang, Wei

    2014-01-01

    degrees C. We focus on probing the effects of oxygen and nitrogen-containing functional groups on supported palladium nanoparticles (NPs) in the model catalytic system. The stability of palladium NPs supported on CNTs depends strongly on the surface properties of CNTs. Moreover, the oxygen...... feature, instability, and subtle response of the components upon application of an external field. Herein, we use insitu TEM, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy techniques to record the interaction in palladium on carbon nanotubes (CNTs) from room temperature to 600...

  5. Frequency response functions for nonlinear convergent systems

    NARCIS (Netherlands)

    Pavlov, A.V.; Wouw, van de N.; Nijmeijer, H.

    2007-01-01

    Convergent systems constitute a practically important class of nonlinear systems that extends the class of asymptotically stable linear time-invariant systems. In this note, we extend frequency response functions defined for linear systems to nonlinear convergent systems. Such nonlinear frequency

  6. NaI(Tl) response functions

    International Nuclear Information System (INIS)

    Vega C, H. R.; Ortiz R, J. M.; Benites R, J. L.; De Leon M, H. A.

    2015-09-01

    The response functions of a NaI(Tl) detector have been estimated using Monte Carlo methods. Response functions were calculated for monoenergetic photon sources (0.05 to 3 MeV). Responses were calculated for point-like sources and for sources distributed in Portland cement cylinders. The responses were used to calculate the efficiency functions in term of photon energy. Commonly, sources used for calibration are point-like, and eventually sources to be measured have different features. In order to use the calibrated sources corrections due to solid angle, self-absorption and scattering, must be carried out. However, some of these corrections are not easy to perform. In this work, the calculated responses were used to estimate the detector efficiency of point-like sources, and sources distributed in Portland type cement. Samples of Portland paste were prepared and were exposed to photoneutrons produced by a 15 MV linac. Some of the elements in the cement were activated producing γ-emitting radionuclides that were measured with a NaI(Tl) gamma-ray spectrometer, that was calibrated with point-like sources. In order to determine the specific activity in the induced radioisotopes calculated efficiencies were used to make corrections due to the differences between the solid angle, photon absorption and photon scattering in the point-like calibration sources and the sources distributed in cement. During the interaction between photoneutrons and the cement samples three radioisotopes were induced: 56 Mn, 24 Na, and 28 Al. (Author)

  7. Ellipsometry of functional organic surfaces and films

    CERN Document Server

    Hinrichs, Karsten

    2013-01-01

    Ellipsometry is the method of choice to determin the properties of surfaces and thin films. It provides comprehensive and sensitive characterization in a contactless and non-invasive measurements. This book gives a state-of-the-art survey of ellipsometric investigations of organic films and surfaces, from laboratory to synchrotron applications, with a special focus on in-situ use in processing environments and at solid-liquid interfaces.

  8. Nanoparticle Surface Functionality Dictates Cellular and Systemic Toxicity

    DEFF Research Database (Denmark)

    Saei, Amir Ata; Yazdani, Mahdieh; Lohse, Samuel E.

    2017-01-01

    can greatly enhance subsequent therapeutic effects of NPs while diminishing their adverse side effects. In this review, we will focus on the effect of surface functionality on the cellular uptake and the transport of NPs by various subcellular processes.......Engineered nanoparticles (NPs) have opened new frontiers in therapeutics and diagnostics in recent years. The surface functionality of these nanoparticles often predominates their interactions with various biological components of human body, and proper selection or control of surface functionality...

  9. Radiological emergency response - a functional approach

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Prosanta [Louisiana Radiation Protection Div., Baton Rouge, LA (United States)

    1997-12-31

    The radiological emergency response program in the State of Louisiana is discussed. The improved approach intends to maximize the efficiency for both nuclear power plant and radiological emergency response as a whole. Several broad-based components are identified: cluster of `nodes` are generated for each component; these `nodes` may be divided into `sub-nodes` which will contain some `attributes`; `relational bonds` among the `attributes` will exist. When executed, the process begins and continues with the `nodes` assuming a functional and dynamic role based on the nature and characteristics of the `attributes`. The typical response based on stand-alone elements is eliminated; overlapping of functions is avoided, and is produced a well-structure and efficient organization 1 ref., 6 figs.; e-mail: prosanta at deq.state.la.us

  10. Radiological emergency response - a functional approach

    International Nuclear Information System (INIS)

    Chowdhury, Prosanta

    1997-01-01

    The radiological emergency response program in the State of Louisiana is discussed. The improved approach intends to maximize the efficiency for both nuclear power plant and radiological emergency response as a whole. Several broad-based components are identified: cluster of 'nodes' are generated for each component; these 'nodes' may be divided into 'sub-nodes' which will contain some 'attributes'; 'relational bonds' among the 'attributes' will exist. When executed, the process begins and continues with the 'nodes' assuming a functional and dynamic role based on the nature and characteristics of the 'attributes'. The typical response based on stand-alone elements is eliminated; overlapping of functions is avoided, and is produced a well-structure and efficient organization

  11. Assessment of Wind Turbine Structural Integrity using Response Surface Methodology

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Svenningsen, Lasse; Moser, Wolfgang

    2016-01-01

    Highlights •A new approach to assessment of site specific wind turbine loads is proposed. •The approach can be applied in both fatigue and ultimate limit state. •Two different response surface methodologies have been investigated. •The model uncertainty introduced by the response surfaces...

  12. Biological response to purification and acid functionalization of carbon nanotubes

    Science.gov (United States)

    Figarol, Agathe; Pourchez, Jérémie; Boudard, Delphine; Forest, Valérie; Tulliani, Jean-Marc; Lecompte, Jean-Pierre; Cottier, Michèle; Bernache-Assollant, Didier; Grosseau, Philippe

    2014-07-01

    Acid functionalization has been considered as an easy way to enhance the dispersion and biodegradation of carbon nanotubes (CNT). However, inconsistencies between toxicity studies of acid functionalized CNT remain unexplained. This could be due to a joint effect of the main physicochemical modifications resulting from an acid functionalization: addition of surface acid groups and purification from catalytic metallic impurities. In this study, the impact on CNT biotoxicity of these two physiochemical features was assessed separately. The in vitro biological response of RAW 264.7 macrophages was evaluated after exposure to 15-240 µg mL-1 of two types of multi-walled CNT. For each type of CNT (small: 20 nm diameter, and big: 90 nm diameter), three different surface chemical properties were studied (total of six CNT samples): pristine, acid functionalized and desorbed. Desorbed CNT were purified by the acid functionalization but presented a very low amount of surface acid groups due to a thermal treatment under vacuum. A Janus effect of acid functionalization with two opposite impacts is highlighted. The CNT purification decreased the overall toxicity, while the surface acid groups intensified it when present at a specific threshold. These acid groups especially amplified the pro-inflammatory response. The threshold mechanism which seemed to regulate the impact of acid groups should be further studied to determine its value and potential link to the other physicochemical state of the CNT. The results suggest that, for a safer-design approach, the benefit-risk balance of an acid functionalization has to be considered, depending on the CNT primary state of purification. Further research should be conducted in this direction.

  13. Green's functions potential fields on surfaces

    CERN Document Server

    Melnikov, Yuri A

    2017-01-01

    This book is comprehensive in its classical mathematical physics presentation, providing the reader with detailed instructions for obtaining Green's functions from scratch. Green's functions is an instrument easily accessible to practitioners who are engaged in design and exploitation of machines and structures in modern engineering practice. To date, there are no books available on the market that are devoted to the Green's function formalism for equations covered in this volume. The reader, with an undergraduate background in applied mathematics, can become an active user of the Green's function approach. For the first time, Green's functions are discussed for a specific class of problems dealing with potential fields induced in thin-wall structures and therefore, the reader will have first-hand access to a novel issue. This Work is accessible to researchers in applied mathematics, mechanics, and relevant disciplines such as engineering, as well as to upper level undergraduates and graduate students.

  14. PEGylated graphene oxide elicits strong immunological responses despite surface passivation

    Science.gov (United States)

    Luo, Nana; Weber, Jeffrey K.; Wang, Shuang; Luan, Binquan; Yue, Hua; Xi, Xiaobo; Du, Jing; Yang, Zaixing; Wei, Wei; Zhou, Ruhong; Ma, Guanghui

    2017-02-01

    Engineered nanomaterials promise to transform medicine at the bio-nano interface. However, it is important to elucidate how synthetic nanomaterials interact with critical biological systems before such products can be safely utilized in humans. Past evidence suggests that polyethylene glycol-functionalized (PEGylated) nanomaterials are largely biocompatible and elicit less dramatic immune responses than their pristine counterparts. We here report results that contradict these findings. We find that PEGylated graphene oxide nanosheets (nGO-PEGs) stimulate potent cytokine responses in peritoneal macrophages, despite not being internalized. Atomistic molecular dynamics simulations support a mechanism by which nGO-PEGs preferentially adsorb onto and/or partially insert into cell membranes, thereby amplifying interactions with stimulatory surface receptors. Further experiments demonstrate that nGO-PEG indeed provokes cytokine secretion by enhancing integrin β8-related signalling pathways. The present results inform that surface passivation does not always prevent immunological reactions to 2D nanomaterials but also suggest applications for PEGylated nanomaterials wherein immune stimulation is desired.

  15. Cell Adhesion on Surface-Functionalized Magnesium.

    Science.gov (United States)

    Wagener, Victoria; Schilling, Achim; Mainka, Astrid; Hennig, Diana; Gerum, Richard; Kelch, Marie-Luise; Keim, Simon; Fabry, Ben; Virtanen, Sannakaisa

    2016-05-18

    The biocompatibility of commercially pure magnesium-based (cp Mg) biodegradable implants is compromised of strong hydrogen evolution and surface alkalization due to high initial corrosion rates of cp Mg in the physiological environment. To mitigate this problem, the addition of corrosion-retarding alloying elements or coating of implant surfaces has been suggested. In the following work, we explored the effect of organic coatings on long-term cell growth. cp Mg was coated with aminopropyltriehtoxysilane + vitamin C (AV), carbonyldiimidazole (CDI), or stearic acid (SA). All three coatings have been previously suggested to reduce initial corrosion and to enhance protein adsorption and hence cell adhesion on magnesium surfaces. Endothelial cells (DH1+/+) and osteosarcoma cells (MG63) were cultured on coated samples for up to 20 days. To quantify Mg corrosion, electrochemical impedance spectroscopy (EIS) was measured after 1, 3, and 5 days of cell culture. We also investigated the speed of initial cell spreading after seeding using fluorescently labeled fibroblasts (NIH/3T3). Hydrogen evolution after contact with cell culture medium was markedly decreased on AV- and SA-coated Mg compared to uncoated Mg. These coatings also showed improved cell adhesion and spreading after 24 h of culture comparable to tissue-treated plastic surfaces. On AV-coated cp Mg, a confluent layer of endothelial cells formed after 5 days and remained intact for up to 20 days. Together, these data demonstrate that surface coating with AV is a viable strategy for improving long-term biocompatibility of cp Mg-based implants. EIS measurements confirmed that the presence of a confluent cell layer increased the corrosion resistance.

  16. Surface functionalized hollow silica particles and composites

    KAUST Repository

    Rodionov, Valentin; Khanh, Vu Bao

    2017-01-01

    Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

  17. Surface functionalized hollow silica particles and composites

    KAUST Repository

    Rodionov, Valentin

    2017-05-26

    Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

  18. Versatile Density Functionals for Computational Surface Science

    DEFF Research Database (Denmark)

    Wellendorff, Jess

    Density functional theory (DFT) emerged almost 50 years ago. Since then DFT has established itself as the central electronic structure methodology for simulating atomicscale systems from a few atoms to a few hundred atoms. This success of DFT is due to a very favorable accuracy-to-computational c......Density functional theory (DFT) emerged almost 50 years ago. Since then DFT has established itself as the central electronic structure methodology for simulating atomicscale systems from a few atoms to a few hundred atoms. This success of DFT is due to a very favorable accuracy...... resampling techniques, thereby systematically avoiding problems with overfitting. The first ever density functional presenting both reliable accuracy and convincing error estimation is generated. The methodology is general enough to be applied to more complex functional forms with higher-dimensional fitting...

  19. Diamond surface functionalization with biomimicry – Amine surface tether and thiol moiety for electrochemical sensors

    Energy Technology Data Exchange (ETDEWEB)

    Sund, James B., E-mail: jim@jamessund.com [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States); Causey, Corey P. [Departments of Chemistry and Biochemistry, Duke University, Durham, NC (United States); Wolter, Scott D. [Department of Physics, Elon University, Elon, NC 27244 (United States); Parker, Charles B., E-mail: charles.parker@duke.edu [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States); Stoner, Brian R. [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States); Research Triangle Institute (RTI) International, Research Triangle Park, NC (United States); Toone, Eric J. [Departments of Chemistry and Biochemistry, Duke University, Durham, NC (United States); Glass, Jeffrey T. [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States)

    2014-05-01

    Highlights: • Diamond surfaces were functionalized with organic molecules using a novel approach. • Used biomimicry to select a molecule to bind NO, similar to the human body. • Molecular orbital theory predicted the molecule-analyte oxidation behavior. • A thiol moiety was attached to an amine surface tether on the diamond surface. • XPS analysis verified each surface functionalization step. - Abstract: The surface of conducting diamond was functionalized with a terminal thiol group that is capable of binding and detecting nitrogen–oxygen species. The functionalization process employed multiple steps starting with doped diamond films grown by plasma enhanced chemical vapor deposition followed by hydrogen termination and photochemical attachment of a chemically protected amine alkene. The surface tether was deprotected to reveal the amine functionality, which enabled the tether to be extended with surface chemistry to add a terminal thiol moiety for electrochemical sensing applications. Each step of the process was validated using X-ray photoelectron spectroscopy analysis.

  20. Diamond surface functionalization with biomimicry – Amine surface tether and thiol moiety for electrochemical sensors

    International Nuclear Information System (INIS)

    Sund, James B.; Causey, Corey P.; Wolter, Scott D.; Parker, Charles B.; Stoner, Brian R.; Toone, Eric J.; Glass, Jeffrey T.

    2014-01-01

    Highlights: • Diamond surfaces were functionalized with organic molecules using a novel approach. • Used biomimicry to select a molecule to bind NO, similar to the human body. • Molecular orbital theory predicted the molecule-analyte oxidation behavior. • A thiol moiety was attached to an amine surface tether on the diamond surface. • XPS analysis verified each surface functionalization step. - Abstract: The surface of conducting diamond was functionalized with a terminal thiol group that is capable of binding and detecting nitrogen–oxygen species. The functionalization process employed multiple steps starting with doped diamond films grown by plasma enhanced chemical vapor deposition followed by hydrogen termination and photochemical attachment of a chemically protected amine alkene. The surface tether was deprotected to reveal the amine functionality, which enabled the tether to be extended with surface chemistry to add a terminal thiol moiety for electrochemical sensing applications. Each step of the process was validated using X-ray photoelectron spectroscopy analysis

  1. Response functions of superfluid neutron matter

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Jochen; Sedrakian, Armen [Institut fuer Theoretische Physik, Goethe Universitaet, 60438 Frankfurt/Main (Germany)

    2011-07-01

    We investigate the response of pair-correlated neutron matter under conditions relevant to neutron stars to external weak probes and compute its neutrino emissivity in vector and axialvector channels. To derive the response functions we sum up an infinite chain of particle-hole ladder diagrams within finite-temperature Green's function theory. The polarization tensor of matter is evaluated in the limit of small momentum transfers. The calculated neutrino emission via the weak neutral current processes of pair-breaking and recombination of Cooper-pairs in neutron stars causes a cooling of their baryonic interior, and represents an important mechanism for the thermal evolution of the star within a certain time domain.

  2. Optical response from functionalized atomically thin nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Malic, Ermin; Berghaeuser, Gunnar; Feierabend, Maja [Department of Physics, Chalmers University of Technology, Gothenburg (Sweden); Knorr, Andreas [Institut fuer Theoretische Physik, Technische Universitaet Berlin (Germany)

    2017-10-15

    Chemical functionalization of atomically thin nanostructures presents a promising strategy to create new hybrid nanomaterials with remarkable and externally controllable properties. Here, we review our research in the field of theoretical modeling of carbon nanotubes, graphene, and transition metal dichalcogenides located in molecular dipole fields. In particular, we provide a microscopic view on the change of the optical response of these technologically promising nanomaterials due to the presence of photo-active spiropyran molecules. The feature article presents a review of recent theoretical work providing microscopic view on the optical response of chemically functionalized carbon nanotubes, graphene, and monolayered transition metal dichalcogenides. In particular, we propose a novel sensor mechanism based on the molecule-induced activation of dark excitons. This results in a pronounced additional peak presenting an unambiguous optical fingerprint for the attached molecules. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Handling of micro objects: investigation of mechanical gripper functional surfaces

    DEFF Research Database (Denmark)

    Gegeckaite, Asta; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2007-01-01

    between the micro object and the gripper do not allow simple picking and releasing of the object. This effect can be overcome by modifying the functional surface of the gripper. The functional surface of the gripper was modified by different machining techniques. The results of this investigation...

  4. Characterization of technical surfaces by structure function analysis

    Science.gov (United States)

    Kalms, Michael; Kreis, Thomas; Bergmann, Ralf B.

    2018-03-01

    The structure function is a tool for characterizing technical surfaces that exhibits a number of advantages over Fourierbased analysis methods. So it is optimally suited for analyzing the height distributions of surfaces measured by full-field non-contacting methods. The structure function is thus a useful method to extract global or local criteria like e. g. periodicities, waviness, lay, or roughness to analyze and evaluate technical surfaces. After the definition of line- and area-structure function and offering effective procedures for their calculation this paper presents examples using simulated and measured data of technical surfaces including aircraft parts.

  5. NaI(Tl) response functions

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R.; Ortiz R, J. M. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico); Benites R, J. L. [Centro Estatal de Cancerologia de Nayarit, Calz. de la Cruz 118 Sur, Tepic, Nayarit (Mexico); De Leon M, H. A., E-mail: fermineutron@yahoo.com.mx [Instituto Tecnologico de Aguascalientes, Av. Adolfo Lopez Mateos 1801 Ote., 20155 Aguascalientes, Ags. (Mexico)

    2015-09-15

    The response functions of a NaI(Tl) detector have been estimated using Monte Carlo methods. Response functions were calculated for monoenergetic photon sources (0.05 to 3 MeV). Responses were calculated for point-like sources and for sources distributed in Portland cement cylinders. The responses were used to calculate the efficiency functions in term of photon energy. Commonly, sources used for calibration are point-like, and eventually sources to be measured have different features. In order to use the calibrated sources corrections due to solid angle, self-absorption and scattering, must be carried out. However, some of these corrections are not easy to perform. In this work, the calculated responses were used to estimate the detector efficiency of point-like sources, and sources distributed in Portland type cement. Samples of Portland paste were prepared and were exposed to photoneutrons produced by a 15 MV linac. Some of the elements in the cement were activated producing γ-emitting radionuclides that were measured with a NaI(Tl) gamma-ray spectrometer, that was calibrated with point-like sources. In order to determine the specific activity in the induced radioisotopes calculated efficiencies were used to make corrections due to the differences between the solid angle, photon absorption and photon scattering in the point-like calibration sources and the sources distributed in cement. During the interaction between photoneutrons and the cement samples three radioisotopes were induced: {sup 56}Mn, {sup 24}Na, and {sup 28}Al. (Author)

  6. The functional response of a generalist predator.

    Directory of Open Access Journals (Sweden)

    Sophie Smout

    Full Text Available BACKGROUND: Predators can have profound impacts on the dynamics of their prey that depend on how predator consumption is affected by prey density (the predator's functional response. Consumption by a generalist predator is expected to depend on the densities of all its major prey species (its multispecies functional response, or MSFR, but most studies of generalists have focussed on their functional response to only one prey species. METHODOLOGY AND PRINCIPAL FINDINGS: Using Bayesian methods, we fit an MSFR to field data from an avian predator (the hen harrier Circus cyaneus feeding on three different prey species. We use a simple graphical approach to show that ignoring the effects of alternative prey can give a misleading impression of the predator's effect on the prey of interest. For example, in our system, a "predator pit" for one prey species only occurs when the availability of other prey species is low. CONCLUSIONS AND SIGNIFICANCE: The Bayesian approach is effective in fitting the MSFR model to field data. It allows flexibility in modelling over-dispersion, incorporates additional biological information into the parameter priors, and generates estimates of uncertainty in the model's predictions. These features of robustness and data efficiency make our approach ideal for the study of long-lived predators, for which data may be sparse and management/conservation priorities pressing.

  7. Calculus on Surfaces with General Closest Point Functions

    KAUST Repository

    Mä rz, Thomas; Macdonald, Colin B.

    2012-01-01

    The closest point method for solving partial differential equations (PDEs) posed on surfaces was recently introduced by Ruuth and Merriman [J. Comput. Phys., 227 (2008), pp. 1943- 1961] and successfully applied to a variety of surface PDEs. In this paper we study the theoretical foundations of this method. The main idea is that surface differentials of a surface function can be replaced with Cartesian differentials of its closest point extension, i.e., its composition with a closest point function. We introduce a general class of these closest point functions (a subset of differentiable retractions), show that these are exactly the functions necessary to satisfy the above idea, and give a geometric characterization of this class. Finally, we construct some closest point functions and demonstrate their effectiveness numerically on surface PDEs. © 2012 Society for Industrial and Applied Mathematics.

  8. Surface energy and work function of elemental metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Rosengaard, N. M.

    1992-01-01

    and noble metals, as derived from the surface tension of liquid metals. In addition, they give work functions which agree with the limited experimental data obtained from single crystals to within 15%, and explain the smooth behavior of the experimental work functions of polycrystalline samples......We have performed an ab initio study of the surface energy and the work function for six close-packed surfaces of 40 elemental metals by means of a Green’s-function technique, based on the linear-muffin-tin-orbitals method within the tight-binding and atomic-sphere approximations. The results...... are in excellent agreement with a recent full-potential, all-electron, slab-supercell calculation of surface energies and work functions for the 4d metals. The present calculations explain the trend exhibited by the surface energies of the alkali, alkaline earth, divalent rare-earth, 3d, 4d, and 5d transition...

  9. Eye surface temperature detects stress response in budgerigars (Melopsittacus undulatus).

    Science.gov (United States)

    Ikkatai, Yuko; Watanabe, Shigeru

    2015-08-05

    Previous studies have suggested that stressors not only increase body core temperature but also body surface temperature in many animals. However, it remains unclear whether surface temperature could be used as an alternative to directly measure body core temperature, particularly in birds. We investigated whether surface temperature is perceived as a stress response in budgerigars. Budgerigars have been used as popular animal models to investigate various neural mechanisms such as visual perception, vocal learning, and imitation. Developing a new technique to understand the basic physiological mechanism would help neuroscience researchers. First, we found that cloacal temperature correlated with eye surface temperature. Second, eye surface temperature increased after handling stress. Our findings suggest that eye surface temperature is closely related to cloacal temperature and that the stress response can be measured by eye surface temperature in budgerigars.

  10. Container Surface Evaluation by Function Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Wendelberger, James G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-03

    Container images are analyzed for specific surface features, such as, pits, cracks, and corrosion. The detection of these features is confounded with complicating features. These complication features include: shape/curvature, welds, edges, scratches, foreign objects among others. A method is provided to discriminate between the various features. The method consists of estimating the image background, determining a residual image and post processing to determine the features present. The methodology is not finalized but demonstrates the feasibility of a method to determine the kind and size of the features present.

  11. Reliability Evaluation of Bridges Based on Nonprobabilistic Response Surface Limit Method

    OpenAIRE

    Chen, Xuyong; Chen, Qian; Bian, Xiaoya; Fan, Jianping

    2017-01-01

    Due to many uncertainties in nonprobabilistic reliability assessment of bridges, the limit state function is generally unknown. The traditional nonprobabilistic response surface method is a lengthy and oscillating iteration process and leads to difficultly solving the nonprobabilistic reliability index. This article proposes a nonprobabilistic response surface limit method based on the interval model. The intention of this method is to solve the upper and lower limits of the nonprobabilistic ...

  12. Response of surface buoy moorings in steady and wave flows

    Digital Repository Service at National Institute of Oceanography (India)

    Anand, N.M.; Nayak, B.U.; SanilKumar, V.

    A numerical model has been developed to evaluate the dynamics of surface buoy mooring systems under wave and current loading. System tension response and variation of tension in the mooring line at various depths have been evaluated for deep water...

  13. Statistical optimization of cultural conditions by response surface ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-08-04

    Aug 4, 2009 ... Full Length Research Paper. Statistical optimization of cultural conditions by response surface methodology for phenol degradation by a novel ... Phenol is a hydrocarbon compound that is highly toxic, ... Microorganism.

  14. Macromolecular surface design: photopatterning of functional stable nitrile oxides.

    Science.gov (United States)

    Altintas, Ozcan; Glassner, Mathias; Rodriguez-Emmenegger, Cesar; Welle, Alexander; Trouillet, Vanessa; Barner-Kowollik, Christopher

    2015-05-04

    The efficient trapping of photogenerated thioaldehydes with functional shelf-stable nitrile oxides in a 1,3-dipolar cycloaddition is a novel and versatile photochemical strategy for polymer end-group functionalization and surface modification under mild and equimolar conditions. The modular ligation in solution was followed in detail by electrospray ionization mass spectrometry (ESI-MS). X-ray photoelectron spectroscopy (XPS) was employed to analyze the functionalized surfaces, whereas time-of-flight secondary-ion mass spectrometry (ToF-SIMS) confirmed the spatial control of the surface functionalization using a micropatterned shadow mask. Polymer brushes were grown from the surface in a spatially confined regime by surface-initiated atom transfer radical polymerization (SI-ATRP) as confirmed by TOF-SIMS, XPS as well as ellipsometry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Toward tuning the surface functionalization of small ceria nanoparticles

    International Nuclear Information System (INIS)

    Huang, Xing; Wang, Binghui; Grulke, Eric A.; Beck, Matthew J.

    2014-01-01

    Understanding and controlling the performance of ceria nanoparticle (CNP) catalysts requires knowledge of the detailed structure and property of CNP surfaces and any attached functional groups. Here we report thermogravimetric analysis results showing that hydrothermally synthesized ∼30 nm CNPs are decorated with 12.9 hydroxyl groups per nm 2 of CNP surface. Quantum mechanical calculations of the density and distribution of bound surface groups imply a scaling relationship for surface group density that balances formal charges in the functionalized CNP system. Computational results for CNPs with only hydroxyl surface groups yield a predicted density of bound hydroxyl groups for ∼30 nm CNPs that is ∼33% higher than measured densities. Quantitative agreement between predicted and measured hydroxyl surface densities is achieved when calculations consider CNPs with both –OH and –O x surface groups. For this more general treatment of CNP surface functionalizations, quantum mechanical calculations predict a range of stable surface group configurations that depend on the chemical potentials of O and H, and demonstrate the potential to tune CNP surface functionalizations by varying temperature and/or partial pressures of O 2 and H 2 O

  16. Functional and structural responses to marine urbanisation

    Science.gov (United States)

    Mayer-Pinto, M.; Cole, V. J.; Johnston, E. L.; Bugnot, A.; Hurst, H.; Airoldi, L.; Glasby, T. M.; Dafforn, K. A.

    2018-01-01

    Urban areas have broad ecological footprints with complex impacts on natural systems. In coastal areas, growing populations are advancing their urban footprint into the ocean through the construction of seawalls and other built infrastructure. While we have some understanding of how urbanisation might drive functional change in terrestrial ecosystems, coastal systems have been largely overlooked. This study is one of the first to directly assess how changes in diversity relate to changes in ecosystem properties and functions (e.g. productivity, filtration rates) of artificial and natural habitats in one of the largest urbanised estuaries in the world, Sydney Harbour. We complemented our surveys with an extensive literature search. We found large and important differences in the community structure and function between artificial and natural coastal habitats. However, differences in diversity and abundance of organisms do not necessarily match observed functional changes. The abundance and composition of important functional groups differed among habitats with rocky shores having 40% and 70% more grazers than seawalls or pilings, respectively. In contrast, scavengers were approximately 8 times more abundant on seawalls than on pilings or rocky shores and algae were more diverse on natural rocky shores and seawalls than on pilings. Our results confirm previous findings in the literature. Oysters were more abundant on pilings than on rocky shores, but were also smaller. Interestingly, these differences in oyster populations did not affect in situ filtration rates between habitats. Seawalls were the most invaded habitats while pilings supported greater secondary productivity than other habitats. This study highlights the complexity of the diversity-function relationship and responses to ocean sprawl in coastal systems. Importantly, we showed that functional properties should be considered independently from structural change if we are to design and manage artificial

  17. Osteoblastic response to pectin nanocoating on titanium surfaces

    DEFF Research Database (Denmark)

    Gurzawska, Katarzyna; Svava, Rikke; Yihua, Yu

    2014-01-01

    with respect to surface properties and osteogenic response in osteoblastic cells. Nanocoatings on titanium surfaces were evaluated by scanning electron microscopy, contact angle measurements, atomic force microscopy, and X-ray photoelectron spectroscopy. The effect of coated RG-Is on cell adhesion, cell...

  18. Improving the Performance of Semiconductor Sensor Devices Using Surface Functionalization

    Science.gov (United States)

    Rohrbaugh, Nathaniel W.

    As production and understanding of III-nitride growth has progressed, this class of material has been used for its semiconducting properties in the fields of computer processing, microelectronics, and LEDs. As understanding of materials properties has advanced, devices were fabricated to be sensitive to environmental surroundings such as pH, gas, or ionic concentration. Simultaneously the world of pharmaceuticals and environmental science has come to the age where the use of wearable devices and active environmental sensing can not only help us learn more about our surroundings, but help save lives. At the crossroads of these two fields work has been done in marrying the high stability and electrical properties of the III-nitrides with the needs of a growing sensor field for various environments and stimuli. Device architecture can only get one so far, and thus the need for well understood surface functionalization techniques has arisen in the field of III-nitride environmental sensing. Many existing schemes for functionalization involve chemistries that may be unfriendly to a biological environment, unstable in solution, or expensive to produce. One possible solution to these issues is the work presented here, which highlights a surface modification scheme utilizing phosphonic acid based chemistry and biomolecular attachment. This dissertation presents a set of studies and experiments quantifying and analyzing the response behaviors of AlGaN/GaN field effect transistor (FET) devices via their interfacial electronic properties. Additional investigation was done on the modification of these surfaces, effects of stressful environmental conditions, and the utility of the phosphonic acid surface treatments. Signals of AlGaN/GaN FETs were measured as IDrain values and in the earliest study an average signal increase of 96.43% was observed when surfaces were incubated in a solution of a known recognition peptide sequence (SVSVGMKPSPRP). This work showed that even without

  19. Modification of surface/neuron interfaces for neural cell-type specific responses: a review

    International Nuclear Information System (INIS)

    Chen, Cen; Kong, Xiangdong; Lee, In-Seop

    2016-01-01

    Surface/neuron interfaces have played an important role in neural repair including neural prostheses and tissue engineered scaffolds. This comprehensive literature review covers recent studies on the modification of surface/neuron interfaces. These interfaces are identified in cases both where the surfaces of substrates or scaffolds were in direct contact with cells and where the surfaces were modified to facilitate cell adhesion and controlling cell-type specific responses. Different sources of cells for neural repair are described, such as pheochromocytoma neuronal-like cell, neural stem cell (NSC), embryonic stem cell (ESC), mesenchymal stem cell (MSC) and induced pluripotent stem cell (iPS). Commonly modified methods are discussed including patterned surfaces at micro- or nano-scale, surface modification with conducting coatings, and functionalized surfaces with immobilized bioactive molecules. These approaches to control cell-type specific responses have enormous potential implications in neural repair. (paper)

  20. A Kind of Nanofluid Consisting of Surface-Functionalized Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yang Xuefei

    2010-01-01

    Full Text Available Abstract A method of surface functionalization of silica nanoparticles was used to prepare a kind of stable nanofluid. The functionalization was achieved by grafting silanes directly to the surface of silica nanoparticles in silica solutions (both a commercial solution and a self-made silica solution were used. The functionalized nanoparticles were used to make nanofluids, in which well-dispersed nanoparticles can keep good stability. One of the unique characteristics of the nanofluids is that no deposition layer forms on the heated surface after a pool boiling process. The nanofluids have applicable prospect in thermal engineering fields with the phase-change heat transfer.

  1. Tunnel flexibility effect on the ground surface acceleration response

    Science.gov (United States)

    Baziar, Mohammad Hassan; Moghadam, Masoud Rabeti; Choo, Yun Wook; Kim, Dong-Soo

    2016-09-01

    Flexibility of underground structures relative to the surrounding medium, referred to as the flexibility ratio, is an important factor that influences their dynamic interaction. This study investigates the flexibility effect of a box-shaped subway tunnel, resting directly on bedrock, on the ground surface acceleration response using a numerical model verified against dynamic centrifuge test results. A comparison of the ground surface acceleration response for tunnel models with different flexibility ratios revealed that the tunnels with different flexibility ratios influence the acceleration response at the ground surface in different ways. Tunnels with lower flexibility ratios have higher acceleration responses at short periods, whereas tunnels with higher flexibility ratios have higher acceleration responses at longer periods. The effect of the flexibility ratio on ground surface acceleration is more prominent in the high range of frequencies. Furthermore, as the flexibility ratio of the tunnel system increases, the acceleration response moves away from the free field response and shifts towards the longer periods. Therefore, the flexibility ratio of the underground tunnels influences the peak ground acceleration (PGA) at the ground surface, and may need to be considered in the seismic zonation of urban areas.

  2. Triboelectric Hydrogen Gas Sensor with Pd Functionalized Surface

    Directory of Open Access Journals (Sweden)

    Sung-Ho Shin

    2016-10-01

    Full Text Available Palladium (Pd-based hydrogen (H2 gas sensors have been widely investigated thanks to its fast reaction and high sensitivity to hydrogen. Various sensing mechanisms have been adopted for H2 gas sensors; however, all the sensors must be powered through an external battery. We report here an H2 gas sensor that can detect H2 by measuring the output voltages generated during contact electrification between two friction surfaces. When the H2 sensor, composed of Pd-coated ITO (indium tin oxide and PET (polyethylene Terephthalate film, is exposed to H2, its output voltage is varied in proportion to H2 concentration because the work function (WF of Pd-coated surface changes, altering triboelectric charging behavior. Specifically, the output voltage of the sensor is gradually increased as exposing H2 concentration increases. Reproducible and sensitive sensor response was observed up 1% H2 exposure. The approach introduced here can easily be adopted to development of triboelectric gas sensors detecting other gas species.

  3. Structures and Functions of Pestivirus Glycoproteins: Not Simply Surface Matters

    Directory of Open Access Journals (Sweden)

    Fun-In Wang

    2015-06-01

    Full Text Available Pestiviruses, which include economically important animal pathogens such as bovine viral diarrhea virus and classical swine fever virus, possess three envelope glycoproteins, namely Erns, E1, and E2. This article discusses the structures and functions of these glycoproteins and their effects on viral pathogenicity in cells in culture and in animal hosts. E2 is the most important structural protein as it interacts with cell surface receptors that determine cell tropism and induces neutralizing antibody and cytotoxic T-lymphocyte responses. All three glycoproteins are involved in virus attachment and entry into target cells. E1-E2 heterodimers are essential for viral entry and infectivity. Erns is unique because it possesses intrinsic ribonuclease (RNase activity that can inhibit the production of type I interferons and assist in the development of persistent infections. These glycoproteins are localized to the virion surface; however, variations in amino acids and antigenic structures, disulfide bond formation, glycosylation, and RNase activity can ultimately affect the virulence of pestiviruses in animals. Along with mutations that are driven by selection pressure, antigenic differences in glycoproteins influence the efficacy of vaccines and determine the appropriateness of the vaccines that are currently being used in the field.

  4. Structures and Functions of Pestivirus Glycoproteins: Not Simply Surface Matters.

    Science.gov (United States)

    Wang, Fun-In; Deng, Ming-Chung; Huang, Yu-Liang; Chang, Chia-Yi

    2015-06-29

    Pestiviruses, which include economically important animal pathogens such as bovine viral diarrhea virus and classical swine fever virus, possess three envelope glycoproteins, namely Erns, E1, and E2. This article discusses the structures and functions of these glycoproteins and their effects on viral pathogenicity in cells in culture and in animal hosts. E2 is the most important structural protein as it interacts with cell surface receptors that determine cell tropism and induces neutralizing antibody and cytotoxic T-lymphocyte responses. All three glycoproteins are involved in virus attachment and entry into target cells. E1-E2 heterodimers are essential for viral entry and infectivity. Erns is unique because it possesses intrinsic ribonuclease (RNase) activity that can inhibit the production of type I interferons and assist in the development of persistent infections. These glycoproteins are localized to the virion surface; however, variations in amino acids and antigenic structures, disulfide bond formation, glycosylation, and RNase activity can ultimately affect the virulence of pestiviruses in animals. Along with mutations that are driven by selection pressure, antigenic differences in glycoproteins influence the efficacy of vaccines and determine the appropriateness of the vaccines that are currently being used in the field.

  5. Multi-functional surfaces with controllable wettability and water adhesion

    Science.gov (United States)

    Anastasiadis, Spiros H.; Frysali, Melani A.; Kenanakis, George; Kaklamani, Georgia; Papoutsakis, Lampros

    The design of multifunctional surfaces based on biomimetic structures has gained the interest of the scientific community. Novel multifunctional surfaces have been developed, able to alter their wetting properties in response to temperature and pH as well as light illumination, by combining proper chemistry and surface micro/nano-structuring using ultrafast (femtosecond) laser irradiation. The combination of the hierarchical surface with a ZnO and/or a responsive polymer coating results in efficient photo-active properties as well as reversible superhydrophobic / superhydrophilic surfaces in response to external stimuli. These surfaces can be optimized to exhibit high or zero water adhesion and/or controllable directionality as well. Moreover, they can be seeded with human fibroblasts to examine the cellular response on both surface roughness and surface chemistry. Acknowledgements: This research has been co-financed by the General Secretariat for Research and Technology (''ARISTEIA II'' Action, SMART-SURF) and the European Union (NFFA Europe -Grant agreement No. 654360).

  6. Response Surface Modeling Tool Suite, Version 1.x

    Energy Technology Data Exchange (ETDEWEB)

    2016-07-05

    The Response Surface Modeling (RSM) Tool Suite is a collection of three codes used to generate an empirical interpolation function for a collection of drag coefficient calculations computed with Test Particle Monte Carlo (TPMC) simulations. The first code, "Automated RSM", automates the generation of a drag coefficient RSM for a particular object to a single command. "Automated RSM" first creates a Latin Hypercube Sample (LHS) of 1,000 ensemble members to explore the global parameter space. For each ensemble member, a TPMC simulation is performed and the object drag coefficient is computed. In the next step of the "Automated RSM" code, a Gaussian process is used to fit the TPMC simulations. In the final step, Markov Chain Monte Carlo (MCMC) is used to evaluate the non-analytic probability distribution function from the Gaussian process. The second code, "RSM Area", creates a look-up table for the projected area of the object based on input limits on the minimum and maximum allowed pitch and yaw angles and pitch and yaw angle intervals. The projected area from the look-up table is used to compute the ballistic coefficient of the object based on its pitch and yaw angle. An accurate ballistic coefficient is crucial in accurately computing the drag on an object. The third code, "RSM Cd", uses the RSM generated by the "Automated RSM" code and the projected area look-up table generated by the "RSM Area" code to accurately compute the drag coefficient and ballistic coefficient of the object. The user can modify the object velocity, object surface temperature, the translational temperature of the gas, the species concentrations of the gas, and the pitch and yaw angles of the object. Together, these codes allow for the accurate derivation of an object's drag coefficient and ballistic coefficient under any conditions with only knowledge of the object's geometry and mass.

  7. Electric fields control the orientation of peptides irreversibly immobilized on radical-functionalized surfaces.

    Science.gov (United States)

    Martin, Lewis J; Akhavan, Behnam; Bilek, Marcela M M

    2018-01-24

    Surface functionalization of an implantable device with bioactive molecules can overcome adverse biological responses by promoting specific local tissue integration. Bioactive peptides have advantages over larger protein molecules due to their robustness and sterilizability. Their relatively small size presents opportunities to control the peptide orientation on approach to a surface to achieve favourable presentation of bioactive motifs. Here we demonstrate control of the orientation of surface-bound peptides by tuning electric fields at the surface during immobilization. Guided by computational simulations, a peptide with a linear conformation in solution is designed. Electric fields are used to control the peptide approach towards a radical-functionalized surface. Spontaneous, irreversible immobilization is achieved when the peptide makes contact with the surface. Our findings show that control of both peptide orientation and surface concentration is achieved simply by varying the solution pH or by applying an electric field as delivered by a small battery.

  8. Spontaneous symmetry breaking and response functions

    International Nuclear Information System (INIS)

    Beraudo, A.; De Pace, A.; Martini, M.; Molinari, A.

    2005-01-01

    We study the quantum phase transition occurring in an infinite homogeneous system of spin 1/2 fermions in a non-relativistic context. As an example we consider neutrons interacting through a simple spin-spin Heisenberg force. The two critical values of the coupling strength-signaling the onset into the system of a finite magnetization and of the total magnetization, respectively-are found and their dependence upon the range of the interaction is explored. The spin response function of the system in the region where the spin-rotational symmetry is spontaneously broken is also studied. For a ferromagnetic interaction the spin response along the direction of the spontaneous magnetization occurs in the particle-hole continuum and displays, for not too large momentum transfers, two distinct peaks. The response along the direction orthogonal to the spontaneous magnetization displays instead, beyond a softened and depleted particle-hole continuum, a collective mode to be identified with a Goldstone boson of type II. Notably, the random phase approximation on a Hartree-Fock basis accounts for it, in particular for its quadratic-close to the origin-dispersion relation. It is shown that the Goldstone boson contributes to the saturation of the energy-weighted sum rule for ∼25% when the system becomes fully magnetized (that is in correspondence of the upper critical value of the interaction strength) and continues to grow as the interaction strength increases

  9. An Intelligent Method for Structural Reliability Analysis Based on Response Surface

    Institute of Scientific and Technical Information of China (English)

    桂劲松; 刘红; 康海贵

    2004-01-01

    As water depth increases, the structural safety and reliability of a system become more and more important and challenging. Therefore, the structural reliability method must be applied in ocean engineering design such as offshore platform design. If the performance function is known in structural reliability analysis, the first-order second-moment method is often used. If the performance function could not be definitely expressed, the response surface method is always used because it has a very clear train of thought and simple programming. However, the traditional response surface method fits the response surface of quadratic polynomials where the problem of accuracy could not be solved, because the true limit state surface can be fitted well only in the area near the checking point. In this paper, an intelligent computing method based on the whole response surface is proposed, which can be used for the situation where the performance function could not be definitely expressed in structural reliability analysis. In this method, a response surface of the fuzzy neural network for the whole area should be constructed first, and then the structural reliability can be calculated by the genetic algorithm. In the proposed method, all the sample points for the training network come from the whole area, so the true limit state surface in the whole area can be fitted. Through calculational examples and comparative analysis, it can be known that the proposed method is much better than the traditional response surface method of quadratic polynomials, because, the amount of calculation of finite element analysis is largely reduced, the accuracy of calculation is improved,and the true limit state surface can be fitted very well in the whole area. So, the method proposed in this paper is suitable for engineering application.

  10. Functionalized surfaces and nanostructures for nanotechnological applications

    Science.gov (United States)

    2003-01-01

    CMOS roadmap in sight at around 10 nm, combined with the uncertainly principal's limit of Von Neuman electronics at 2 nm, that merely making things smaller will not help us. Replacing CMOS transistors on a one for one basis with some type of nano device would have the effect of drastically increasing fabrication costs, while offering only a marginal improvement over current technologies. However, nanotechnology offers us a way out of this technological and financial cul-de-sac by building devices from the bottom up. Techniques such as self assembly, perhaps assisted by templates created by nano imprint lithography, a notable European success, combined with our understanding of the workings of polymers and molecules such as Rotoxane at the nanoscale open up a whole new host of possibilities. Whether it is avoiding Moore's second law by switching to plastic electronics, or using molecular electronics, our understanding of the behaviour of materials on the scale of small molecules allows a variety of alternative approaches, to produce smarter, cheaper devices. The new understandings will also allow us to design new architectures, with the end result that functionality will become a more valid measure of performance than transistor density or operations per second. 8. Nanotechnology is new It often comes as a surprise to learn that the Romans and Chinese were using nanoparticles thousands of years ago. Similarly, every time you light a match, fullerenes are produced. Degusssa have been producing carbon black, the substance that makes car tyres black and improves the wear resistance of the rubber, since the 1920s. Of course they were not aware that they were using nanotechnology, and as they had no control over particle size, or even any knowledge of the nanoscale they were not using nanotechnology as currently defined. What is new about nanotechnology is our ability to not only see, and manipulate matter on the nanoscale, but our understanding of atomic scale interactions

  11. Functional, Responsive Materials Assembled from Recombinant Oleosin

    Science.gov (United States)

    Hammer, Daniel

    Biological cells are surrounded by a plasma membrane made primarily of phospholipids that form a bilayer. This membrane is permselective and compartmentalizes the cell. A simple form of artificial cell is the vesicle, in which a phospholipid bilayer membrane surrounds an aqueous solution. However, there is no a priori reason why a membrane needs to be made of phospholipids. It could be made of any surfactant that forms a bilayer. We have assembled membranes and other structures from the recombinant plant protein oleosin. The ability to assemble from a recombinant protein means that every molecule is identical, we have complete control over the sequence, and hence can build in designer functionality with high fidelity, including adhesion and enzymatic activity. Such incorporation is trivial using the tools of molecular biology. We find that while many variants of oleosin make membranes, others make micelles and sheets. We show how the type of supramolecular structure can be altered by the conditions of solvent, such as ionic strength, and the architecture of the surfactant itself. We show that protease cleavable domains can be incorporated within oleosin, and be engineered to protect other functional domains such as adhesive motifs, to make responsive materials whose activity and shape depend on the action of proteases. We will also present the idea of making ``Franken''-oleosins, where large domains of native oleosin are replaced with domains from other functional proteins, to make hybrids conferred by the donor protein. Thus, we can view oleosin as a template upon which a vast array of designer functionalities can be imparted..

  12. Responses of fibroblasts and glial cells to nanostructured platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pennisi, C P; Sevcencu, C; Yoshida, K [Center for Sensory-Motor Interaction (SMI), Aalborg University, Aalborg (Denmark); Dolatshahi-Pirouz, A; Foss, M; Larsen, A Nylandsted; Besenbacher, F [Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus (Denmark); Hansen, J Lundsgaard [Department of Physics and Astronomy, Aarhus University, Aarhus (Denmark); Zachar, V, E-mail: cpennisi@hst.aau.d [Laboratory for Stem Cell Research, Aalborg University (Denmark)

    2009-09-23

    The chronic performance of implantable neural prostheses is affected by the growth of encapsulation tissue onto the stimulation electrodes. Encapsulation is associated with activation of connective tissue cells at the electrode's metallic contacts, usually made of platinum. Since surface nanotopography can modulate the cellular responses to materials, the aim of the present work was to evaluate the 'in vitro' responses of connective tissue cells to platinum strictly by modulating its surface nanoroughness. Using molecular beam epitaxy combined with sputtering, we produced platinum nanostructured substrates consisting of irregularly distributed nanopyramids and investigated their effect on the proliferation, cytoskeletal organization and cellular morphology of primary fibroblasts and transformed glial cells. Cells were cultured on these substrates and their responses to surface roughness were studied. After one day in culture, the fibroblasts were more elongated and their cytoskeleton less mature when cultured on rough substrates. This effect increased as the roughness of the surface increased and was associated with reduced cell proliferation throughout the observation period (4 days). Morphological changes also occurred in glial cells, but they were triggered by a different roughness scale and did not affect cellular proliferation. In conclusion, surface nanotopography modulates the responses of fibroblasts and glial cells to platinum, which may be an important factor in optimizing the tissue response to implanted neural electrodes.

  13. Response predictions using the observed autocorrelation function

    DEFF Research Database (Denmark)

    Nielsen, Ulrik Dam; H. Brodtkorb, Astrid; Jensen, Jørgen Juncher

    2018-01-01

    This article studies a procedure that facilitates short-time, deterministic predictions of the wave-induced motion of a marine vessel, where it is understood that the future motion of the vessel is calculated ahead of time. Such predictions are valuable to assist in the execution of many marine......-induced response in study. Thus, predicted (future) values ahead of time for a given time history recording are computed through a mathematical combination of the sample autocorrelation function and previous measurements recorded just prior to the moment of action. Importantly, the procedure does not need input...... show that predictions can be successfully made in a time horizon corresponding to about 8-9 wave periods ahead of current time (the moment of action)....

  14. Surface Functionalization and Targeting Strategies of Liposomes in Solid Tumor Therapy: A Review

    Science.gov (United States)

    Riaz, Muhammad Kashif; Riaz, Muhammad Adil; Zhang, Xue; Lin, Congcong; Wong, Ka Hong; Chen, Xiaoyu; Lu, Aiping

    2018-01-01

    Surface functionalization of liposomes can play a key role in overcoming the current limitations of nanocarriers to treat solid tumors, i.e., biological barriers and physiological factors. The phospholipid vesicles (liposomes) containing anticancer agents produce fewer side effects than non-liposomal anticancer formulations, and can effectively target the solid tumors. This article reviews information about the strategies for targeting of liposomes to solid tumors along with the possible targets in cancer cells, i.e., extracellular and intracellular targets and targets in tumor microenvironment or vasculature. Targeting ligands for functionalization of liposomes with relevant surface engineering techniques have been described. Stimuli strategies for enhanced delivery of anticancer agents at requisite location using stimuli-responsive functionalized liposomes have been discussed. Recent approaches for enhanced delivery of anticancer agents at tumor site with relevant surface functionalization techniques have been reviewed. Finally, current challenges of functionalized liposomes and future perspective of smart functionalized liposomes have been discussed. PMID:29315231

  15. Surface Functionalization and Targeting Strategies of Liposomes in Solid Tumor Therapy: A Review

    Directory of Open Access Journals (Sweden)

    Muhammad Kashif Riaz

    2018-01-01

    Full Text Available Surface functionalization of liposomes can play a key role in overcoming the current limitations of nanocarriers to treat solid tumors, i.e., biological barriers and physiological factors. The phospholipid vesicles (liposomes containing anticancer agents produce fewer side effects than non-liposomal anticancer formulations, and can effectively target the solid tumors. This article reviews information about the strategies for targeting of liposomes to solid tumors along with the possible targets in cancer cells, i.e., extracellular and intracellular targets and targets in tumor microenvironment or vasculature. Targeting ligands for functionalization of liposomes with relevant surface engineering techniques have been described. Stimuli strategies for enhanced delivery of anticancer agents at requisite location using stimuli-responsive functionalized liposomes have been discussed. Recent approaches for enhanced delivery of anticancer agents at tumor site with relevant surface functionalization techniques have been reviewed. Finally, current challenges of functionalized liposomes and future perspective of smart functionalized liposomes have been discussed.

  16. Resting state functional connectivity predicts neurofeedback response

    Directory of Open Access Journals (Sweden)

    Dustin eScheinost

    2014-09-01

    Full Text Available Tailoring treatments to the specific needs and biology of individual patients – personalized medicine – requires delineation of reliable predictors of response. Unfortunately, these have been slow to emerge, especially in neuropsychiatric disorders. We have recently described a real-time functional magnetic resonance imaging (rt-fMRI neurofeedback protocol that can reduce contamination-related anxiety, a prominent symptom of many cases of obsessive-compulsive disorder (OCD. Individual response to this intervention is variable. Here we used patterns of brain functional connectivity, as measured by baseline resting-state fMRI (rs-fMRI, to predict improvements in contamination anxiety after neurofeedback training. Activity of a region of the orbitofrontal cortex (OFC and anterior prefrontal cortex, Brodmann area (BA 10, associated with contamination anxiety in each subject was measured in real time and presented as a neurofeedback signal, permitting subjects to learn to modulate this target brain region. We have previously reported both enhanced OFC/BA 10 control and improved anxiety in a group of subclinically anxious subjects after neurofeedback. Five individuals with contamination-related OCD who underwent the same protocol also showed improved clinical symptomatology. In both groups, these behavioral improvements were strongly correlated with baseline whole-brain connectivity in the OFC/BA 10, computed from rs-fMRI collected several days prior to neurofeedback training. These pilot data suggest that rs-fMRI can be used to identify individuals likely to benefit from rt-fMRI neurofeedback training to control contamination anxiety.

  17. Diamond surface functionalization with biomimicry - Amine surface tether and thiol moiety for electrochemical sensors

    Science.gov (United States)

    Sund, James B.; Causey, Corey P.; Wolter, Scott D.; Parker, Charles B.; Stoner, Brian R.; Toone, Eric J.; Glass, Jeffrey T.

    2014-05-01

    The surface of conducting diamond was functionalized with a terminal thiol group that is capable of binding and detecting nitrogen-oxygen species. The functionalization process employed multiple steps starting with doped diamond films grown by plasma enhanced chemical vapor deposition followed by hydrogen termination and photochemical attachment of a chemically protected amine alkene. The surface tether was deprotected to reveal the amine functionality, which enabled the tether to be extended with surface chemistry to add a terminal thiol moiety for electrochemical sensing applications. Each step of the process was validated using X-ray photoelectron spectroscopy analysis.

  18. Modeling the microstructure of surface by applying BRDF function

    Science.gov (United States)

    Plachta, Kamil

    2017-06-01

    The paper presents the modeling of surface microstructure using a bidirectional reflectance distribution function. This function contains full information about the reflectance properties of the flat surfaces - it is possible to determine the share of the specular, directional and diffuse components in the reflected luminous stream. The software is based on the authorial algorithm that uses selected elements of this function models, which allows to determine the share of each component. Basing on obtained data, the surface microstructure of each material can be modeled, which allows to determine the properties of this materials. The concentrator directs the reflected solar radiation onto the photovoltaic surface, increasing, at the same time, the value of the incident luminous stream. The paper presents an analysis of selected materials that can be used to construct the solar concentrator system. The use of concentrator increases the power output of the photovoltaic system by up to 17% as compared to the standard solution.

  19. Reliability-based design optimization via high order response surface method

    International Nuclear Information System (INIS)

    Li, Hong Shuang

    2013-01-01

    To reduce the computational effort of reliability-based design optimization (RBDO), the response surface method (RSM) has been widely used to evaluate reliability constraints. We propose an efficient methodology for solving RBDO problems based on an improved high order response surface method (HORSM) that takes advantage of an efficient sampling method, Hermite polynomials and uncertainty contribution concept to construct a high order response surface function with cross terms for reliability analysis. The sampling method generates supporting points from Gauss-Hermite quadrature points, which can be used to approximate response surface function without cross terms, to identify the highest order of each random variable and to determine the significant variables connected with point estimate method. The cross terms between two significant random variables are added to the response surface function to improve the approximation accuracy. Integrating the nested strategy, the improved HORSM is explored in solving RBDO problems. Additionally, a sampling based reliability sensitivity analysis method is employed to reduce the computational effort further when design variables are distributional parameters of input random variables. The proposed methodology is applied on two test problems to validate its accuracy and efficiency. The proposed methodology is more efficient than first order reliability method based RBDO and Monte Carlo simulation based RBDO, and enables the use of RBDO as a practical design tool.

  20. Response Ant Colony Optimization of End Milling Surface Roughness

    Directory of Open Access Journals (Sweden)

    Ahmed N. Abd Alla

    2010-03-01

    Full Text Available Metal cutting processes are important due to increased consumer demands for quality metal cutting related products (more precise tolerances and better product surface roughness that has driven the metal cutting industry to continuously improve quality control of metal cutting processes. This paper presents optimum surface roughness by using milling mould aluminium alloys (AA6061-T6 with Response Ant Colony Optimization (RACO. The approach is based on Response Surface Method (RSM and Ant Colony Optimization (ACO. The main objectives to find the optimized parameters and the most dominant variables (cutting speed, feedrate, axial depth and radial depth. The first order model indicates that the feedrate is the most significant factor affecting surface roughness.

  1. Calculation of the spin-isospin response functions in an extended semi-classical theory

    International Nuclear Information System (INIS)

    Chanfray, G.

    1987-01-01

    We present a semi-classical calculation of the spin isospin response-functions beyond Thomas-Fermi theory. We show that surface-peaked ℎ 2 corrections reduce the collective effects predicted by Thomas-Fermi calculations. These effects, small for a volume response, become important for surface responses probed by hadrons. This yields a considerable improvement of the agreement with the (p, p') Los Alamos data

  2. Osteoblastic response to pectin nanocoating on titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gurzawska, Katarzyna, E-mail: kagu@sund.ku.dk [Research Center for Ageing and Osteoporosis, Departments of Medicine and Diagnostics, Copenhagen University Hospital Glostrup, Ndr. Ringvej 57, 2600 Glostrup (Denmark); Institute of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Nørre Allé 20, 2200 Copenhagen N (Denmark); Svava, Rikke [Department of Plant Environment Sciences, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C (Denmark); Copenhagen Center for Glycomics, Institute for Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N (Denmark); Yihua, Yu; Haugshøj, Kenneth Brian [Microtechnology and Surface Analysis, Danish Technological Institute, Gregersensvej 8, 2630 Taastrup (Denmark); Dirscherl, Kai [Dansk Fundamental Metrologi A/S, Matematiktorvet 307, 2800 Lyngby (Denmark); Levery, Steven B. [Copenhagen Center for Glycomics, Institute for Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N (Denmark); Byg, Inge [Department of Plant Environment Sciences, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C (Denmark); Damager, Iben [Novozymes A/S, Krogshoejvej 36, 2880 Bagsvaerd (Denmark); Nielsen, Martin W. [Department of Systems Biology, Technical University of Denmark, Matematiktorvet, Building 301, Kgs. Lyngby DK-2800 (Denmark); Jørgensen, Bodil [Department of Plant Environment Sciences, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C (Denmark); Jørgensen, Niklas Rye [Research Center for Ageing and Osteoporosis, Departments of Medicine and Diagnostics, Copenhagen University Hospital Glostrup, Ndr. Ringvej 57, 2600 Glostrup (Denmark); and others

    2014-10-01

    Osseointegration of titanium implants can be improved by organic and inorganic nanocoating of the surface. The aim of our study was to evaluate the effect of organic nanocoating of titanium surface with unmodified and modified pectin Rhamnogalacturonan-Is (RG-Is) isolated from potato and apple with respect to surface properties and osteogenic response in osteoblastic cells. Nanocoatings on titanium surfaces were evaluated by scanning electron microscopy, contact angle measurements, atomic force microscopy, and X-ray photoelectron spectroscopy. The effect of coated RG-Is on cell adhesion, cell viability, bone matrix formation and mineralization was tested using SaOS-2 cells. Nanocoating with pectin RG-Is affected surface properties and in consequence changed the environment for cellular response. The cells cultured on surfaces coated with RG-Is from potato with high content of linear 1.4-linked galactose produced higher level of mineralized matrix compared with control surfaces and surfaces coated with RG-I with low content of linear 1.4-linked galactose. The study showed that the pectin RG-Is nanocoating not only changed chemical and physical titanium surface properties, but also specific coating with RG-Is containing high amount of galactan increased mineralized matrix formation of osteoblastic cells in vitro. - Highlights: • Surface nanocoating with plant-derived Rhamnogalacturonan-I (RG-I) is proposed. • Titanium surface became more hydrophilic after RG-Is nanocoating. • RG-Is with high galactose content resulted in high level of mineralized matrix. • RG-I is a new candidate for improvement of bone healing and osseointegration.

  3. Application of response surfaces for reliability analysis of marine structures

    International Nuclear Information System (INIS)

    Leira, Bernt J.; Holmas, Tore; Herfjord, Kjell

    2005-01-01

    Marine structures subjected to multiple environmental loads (i.e. waves, current, wind) are considered. These loads are characterized by a set of corresponding parameters. The structural fatigue damage and long-term response are expressed in terms of these environmental parameters based on application of polynomial response surfaces. For both types of analysis, an integration across the range of variation for all the environmental parameters is required. The location of the intervals which give rise to the dominant contribution for these integrals depends on the relative magnitude of the coefficients defining the polynomials. The required degree of numerical subdivision in order to obtain accurate results is also of interest. These issues are studied on a non-dimensional form. The loss of accuracy which results when applying response surfaces of too low order is also investigated. Response surfaces with cut-off limits at specific lower-bound values for the environmental parameters are further investigated. Having obtained general expressions on non-dimensional form, examples which correspond to specific response quantities for marine structures are considered. Typical values for the polynomial coefficients, and for the statistical distributions representing the environmental parameters, are applied. Convergence studies are subsequently performed for the particular example response quantities in order to make comparison with the general formulation. For the extreme response, the application of 'extreme contours' obtained from the statistical distributions of the environmental parameters is explored

  4. Surface Functionalization of Thin-Film Composite Membranes with Copper Nanoparticles for Antimicrobial Surface Properties

    KAUST Repository

    Ben-Sasson, Moshe

    2014-01-07

    Biofouling is a major operational challenge in reverse osmosis (RO) desalination, motivating a search for improved biofouling control strategies. Copper, long known for its antibacterial activity and relatively low cost, is an attractive potential biocidal agent. In this paper, we present a method for loading copper nanoparticles (Cu-NPs) on the surface of a thin-film composite (TFC) polyamide RO membrane. Cu-NPs were synthesized using polyethyleneimine (PEI) as a capping agent, resulting in particles with an average radius of 34 nm and a copper content between 39 and 49 wt.%. The positive charge of the Cu-NPs imparted by the PEI allowed a simple electrostatic functionalization of the negatively charged RO membrane. We confirmed functionalization and irreversible binding of the Cu-NPs to the membrane surface with SEM and XPS after exposing the membrane to bath sonication. We also demonstrated that Cu-NP functionalization can be repeated after the Cu-NPs dissolve from the membrane surface. The Cu-NP functionalization had minimal impact on the intrinsic membrane transport parameters. Surface hydrophilicity and surface roughness were also maintained, and the membrane surface charge became positive after functionalization. The functionalized membrane exhibited significant antibacterial activity, leading to an 80-95% reduction in the number of attached live bacteria for three different model bacterial strains. Challenges associated with this functionalization method and its implementation in RO desalination are discussed. © 2013 American Chemical Society.

  5. Surface Functionalization of Thin-Film Composite Membranes with Copper Nanoparticles for Antimicrobial Surface Properties

    KAUST Repository

    Ben-Sasson, Moshe; Zodrow, Katherine R.; Genggeng, Qi; Kang, Yan; Giannelis, Emmanuel P.; Elimelech, Menachem

    2014-01-01

    Biofouling is a major operational challenge in reverse osmosis (RO) desalination, motivating a search for improved biofouling control strategies. Copper, long known for its antibacterial activity and relatively low cost, is an attractive potential biocidal agent. In this paper, we present a method for loading copper nanoparticles (Cu-NPs) on the surface of a thin-film composite (TFC) polyamide RO membrane. Cu-NPs were synthesized using polyethyleneimine (PEI) as a capping agent, resulting in particles with an average radius of 34 nm and a copper content between 39 and 49 wt.%. The positive charge of the Cu-NPs imparted by the PEI allowed a simple electrostatic functionalization of the negatively charged RO membrane. We confirmed functionalization and irreversible binding of the Cu-NPs to the membrane surface with SEM and XPS after exposing the membrane to bath sonication. We also demonstrated that Cu-NP functionalization can be repeated after the Cu-NPs dissolve from the membrane surface. The Cu-NP functionalization had minimal impact on the intrinsic membrane transport parameters. Surface hydrophilicity and surface roughness were also maintained, and the membrane surface charge became positive after functionalization. The functionalized membrane exhibited significant antibacterial activity, leading to an 80-95% reduction in the number of attached live bacteria for three different model bacterial strains. Challenges associated with this functionalization method and its implementation in RO desalination are discussed. © 2013 American Chemical Society.

  6. Mechanical response of wall-patterned GaAs surface

    International Nuclear Information System (INIS)

    Le Bourhis, E.; Patriarche, G.

    2005-01-01

    Wall-patterned GaAs surfaces have been elaborated by photolithography and dry etching. Different surfaces were produced in order to change the aspect ratio of the walls formed at the substrate surface. The mechanical behaviour of individual walls was investigated by nanoindentation and the responses were compared to that of a standard bulk reference (flat surface). Deviation from the bulk response is detected in a load range of 1-25 mN depending on the aspect ratio of the walls. A central plastic zone criterion is proposed in view of transmission electron microscopy images of indented walls and allows the prediction of the response deviation of a given wall if its width is known. The mechanical response of the different types of walls is further investigated in terms of stiffness, total penetration of indenter and apparent hardness, and is scanned in relation to the proximity of a wall side. Overall results show that contact stiffness remains almost unaffected by aspect ratio, while penetration drastically increases because of the free sides of the wall as compared to a flat surface (bulk substrate). The application of substrate patterning for optoelectronic devices is discussed in the perspective of eliminating residual dislocations appearing in mismatched structures

  7. Microarray of DNA probes on carboxylate functional beads surface

    Institute of Scientific and Technical Information of China (English)

    黄承志; 李原芳; 黄新华; 范美坤

    2000-01-01

    The microarray of DNA probes with 5’ -NH2 and 5’ -Tex/3’ -NH2 modified terminus on 10 um carboxylate functional beads surface in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) is characterized in the preseni paper. it was found that the microarray capacity of DNA probes on the beads surface depends on the pH of the aqueous solution, the concentra-tion of DNA probe and the total surface area of the beads. On optimal conditions, the minimum distance of 20 mer single-stranded DNA probe microarrayed on beads surface is about 14 nm, while that of 20 mer double-stranded DNA probes is about 27 nm. If the probe length increases from 20 mer to 35 mer, its microarray density decreases correspondingly. Mechanism study shows that the binding mode of DNA probes on the beads surface is nearly parallel to the beads surface.

  8. Microarray of DNA probes on carboxylate functional beads surface

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The microarray of DNA probes with 5′-NH2 and 5′-Tex/3′-NH2 modified terminus on 10 m m carboxylate functional beads surface in the presence of 1-ethyl-3-(3-dimethylaminopropyl)- carbodiimide (EDC) is characterized in the present paper. It was found that the microarray capacity of DNA probes on the beads surface depends on the pH of the aqueous solution, the concentration of DNA probe and the total surface area of the beads. On optimal conditions, the minimum distance of 20 mer single-stranded DNA probe microarrayed on beads surface is about 14 nm, while that of 20 mer double-stranded DNA probes is about 27 nm. If the probe length increases from 20 mer to 35 mer, its microarray density decreases correspondingly. Mechanism study shows that the binding mode of DNA probes on the beads surface is nearly parallel to the beads surface.

  9. Optimization of galacto-oligosacharides synthesis using response surface methodology

    Directory of Open Access Journals (Sweden)

    Carević Milica B.

    2017-01-01

    Full Text Available Galacto-oligosaccharides (GOS are important lactose-derived compounds, considered to be a prebiotics, based on abundant scientific evidence about their unique physical properties and physiological effects. This consequently allows their widespread application as supplement in food and feed industry. They are preferably produced by the enzymatic transgalactosylation action of β-galactosidase. However, this enzyme simultaneously performs its primary biological function of lactose hydrolysis, and it is of crucial importance to gain an insight into the influence of different reaction conditions, and provide favorization of transgalactosylation, particularly GOS synthesis reaction. In this study, the response surface methodology (RSM was applied in terms of individual experimental factors effect estimation, their mutual interaction identification and finally, the determination of optimum conditions for highest GOS yield achievement. Having said that, it can be observed that the temperature and pH have no significant impact on the GOS yield, while on the other hand, the lactose concentration of 400 g/l, enzyme concentration of 13.5 g/l and reaction time of 13 min represent the optimum conditions for achieving the highest GOS yields.

  10. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pruna, R., E-mail: rpruna@el.ub.edu; Palacio, F.; López, M. [SIC, Departament d' Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain); Pérez, J. [Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, E-08028 Barcelona (Spain); Mir, M. [Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, E-08028 Barcelona (Spain); Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Monforte de Lemos 3-5 Pabellón 11, E-28029 Madrid (Spain); Blázquez, O.; Hernández, S.; Garrido, B. [MIND-IN" 2UB, Departament d' Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain)

    2016-08-08

    The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructured ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.

  11. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces

    International Nuclear Information System (INIS)

    Pruna, R.; Palacio, F.; López, M.; Pérez, J.; Mir, M.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Blázquez, O.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Hernández, S.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Garrido, B.

    2016-01-01

    The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructured ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.

  12. Will surface winds weaken in response to global warming?

    Science.gov (United States)

    Ma, Jian; Foltz, Gregory R.; Soden, Brian J.; Huang, Gang; He, Jie; Dong, Changming

    2016-12-01

    The surface Walker and tropical tropospheric circulations have been inferred to slow down from historical observations and model projections, yet analysis of large-scale surface wind predictions is lacking. Satellite measurements of surface wind speed indicate strengthening trends averaged over the global and tropical oceans that are supported by precipitation and evaporation changes. Here we use corrected anemometer-based observations to show that the surface wind speed has not decreased in the averaged tropical oceans, despite its reduction in the region of the Walker circulation. Historical simulations and future projections for climate change also suggest a near-zero wind speed trend averaged in space, regardless of the Walker cell change. In the tropics, the sea surface temperature pattern effect acts against the large-scale circulation slow-down. For higher latitudes, the surface winds shift poleward along with the eddy-driven mid-latitude westerlies, resulting in a very small contribution to the global change in surface wind speed. Despite its importance for surface wind speed change, the influence of the SST pattern change on global-mean rainfall is insignificant since it cannot substantially alter the global energy balance. As a result, the precipitation response to global warming remains ‘muted’ relative to atmospheric moisture increase. Our results therefore show consistency between projections and observations of surface winds and precipitation.

  13. Functionalized polymer film surfaces via surface-initiated atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Hu, Y.; Li, J.S.; Yang, W.T.; Xu, F.J.

    2013-01-01

    The ability to manipulate and control the surface properties of polymer films, without altering the substrate properties, is crucial to their wide-spread applications. In this work, a simple one-step method for the direct immobilization of benzyl chloride groups (as the effective atom transfer radical polymerization (ATRP) initiators) on the polymer films was developed via benzophenone-induced coupling of 4-vinylbenzyl chloride (VBC). Polyethylene (PE) and nylon films were selected as examples of polymer films to illustrate the functionalization of film surfaces via surface-initiated ATRP. Functional polymer brushes of (2-dimethylamino)ethyl methacrylate, sodium 4-styrenesulfonate, 2-hydroxyethyl methacrylate and glycidyl methacrylate, as well as their block copolymer brushes, have been prepared via surface-initiated ATRP from the VBC-coupled PE or nylon film surfaces. With the development of a simple approach to the covalent immobilization of ATRP initiators on polymer film surfaces and the inherent versatility of surface-initiated ATRP, the surface functionality of polymer films can be precisely tailored. - Highlights: ► Atom transfer radical polymerization initiators were simply immobilized. ► Different functional polymer brushes were readily prepared. ► Their block copolymer brushes were also readily prepared

  14. Linear response theory of activated surface diffusion with interacting adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Marti' nez-Casado, R. [Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); Sanz, A.S.; Vega, J.L. [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain); Rojas-Lorenzo, G. [Instituto Superior de Tecnologi' as y Ciencias Aplicadas, Ave. Salvador Allende, esq. Luaces, 10400 La Habana (Cuba); Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain); Miret-Artes, S., E-mail: s.miret@imaff.cfmac.csic.es [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain)

    2010-05-12

    Graphical abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed. - Abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed.

  15. Gelatin Functionalization of Biomaterial Surfaces: Strategies for Immobilization and Visualization

    Directory of Open Access Journals (Sweden)

    Peter Dubruel

    2011-01-01

    Full Text Available In the present work, the immobilization of gelatin as biopolymer on two types of implantable biomaterials, polyimide and titanium, was compared. Both materials are known for their biocompatibility while lacking cell-interactive behavior. For both materials, a pre-functionalization step was required to enable gelatin immobilization. For the polyimide foils, a reactive succinimidyl ester was introduced first on the surface, followed by covalent grafting of gelatin. For the titanium material, methacrylate groups were first introduced on the Ti surface through a silanization reaction. The applied functionalities enabled the subsequent immobilization of methacrylamide modified gelatin. Both surface modified materials were characterized in depth using atomic force microscopy, static contact angle measurements, confocal fluorescence microscopy, attenuated total reflection infrared spectroscopy and X-ray photo-electron spectroscopy. The results indicated that the strategies elaborated for both material classes are suitable to apply stable gelatin coatings. Interestingly, depending on the material class studied, not all surface analysis techniques are applicable.

  16. Recommended values of clean metal surface work functions

    International Nuclear Information System (INIS)

    Derry, Gregory N.; Kern, Megan E.; Worth, Eli H.

    2015-01-01

    A critical review of the experimental literature for measurements of the work functions of clean metal surfaces of single-crystals is presented. The tables presented include all results found for low-index crystal faces except cases that were known to be contaminated surfaces. These results are used to construct a recommended value of the work function for each surface examined, along with an uncertainty estimate for that value. The uncertainties are based in part on the error distribution for all measured work functions in the literature, which is included here. The metals included in this review are silver (Ag), aluminum (Al), gold (Au), copper (Cu), iron (Fe), iridium (Ir), molybdenum (Mo), niobium (Nb), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), tantalum (Ta), and tungsten (W)

  17. Recommended values of clean metal surface work functions

    Energy Technology Data Exchange (ETDEWEB)

    Derry, Gregory N., E-mail: gderry@loyola.edu; Kern, Megan E.; Worth, Eli H. [Department of Physics, Loyola University Maryland, 4501 N. Charles St., Baltimore, Maryland 21210 (United States)

    2015-11-15

    A critical review of the experimental literature for measurements of the work functions of clean metal surfaces of single-crystals is presented. The tables presented include all results found for low-index crystal faces except cases that were known to be contaminated surfaces. These results are used to construct a recommended value of the work function for each surface examined, along with an uncertainty estimate for that value. The uncertainties are based in part on the error distribution for all measured work functions in the literature, which is included here. The metals included in this review are silver (Ag), aluminum (Al), gold (Au), copper (Cu), iron (Fe), iridium (Ir), molybdenum (Mo), niobium (Nb), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), tantalum (Ta), and tungsten (W)

  18. Work functions and surface charges at metallic facet edges

    International Nuclear Information System (INIS)

    Fall, C.J.; Binggeli, N.; Baldereschi, A.

    2002-04-01

    The electronic charge densities and work functions at sharp metallic facet edges are determined from ab initio calculations, combined with macroscopic averaging techniques. In particular, we examine how two different work functions coexist at close range near edges between inequivalent facets. The surface ionic relaxation at facet edges is shown to influence appreciably the local electrostatic potential in the vacuum. Various edges between Al(100) and Al(111) facets are studied, as well as between Na(110) facets. We also develop a model of electronic surface dipoles, which accounts for the surface charge transfer between inequivalent facets, and which allows us to predict the influence of the shape and size of a macroscopic crystal on its work functions. (author)

  19. Meromorphic functions and cohomology on a Riemann surface

    International Nuclear Information System (INIS)

    Gomez-Mont, X.

    1989-01-01

    The objective of this set of notes is to introduce a series of concepts of Complex Analytic Geometry on a Riemann Surface. We motivate the introduction of cohomology groups through the analysis of meromorphic functions. We finish by showing that the set of infinitesimal deformations of a Riemann surface (the tangent space to Teichmueller space) may be computed as a Cohomology group. (author). 6 refs

  20. The utilization of the response surface methodology for the ...

    African Journals Online (AJOL)

    SERVER

    2007-12-03

    Dec 3, 2007 ... Drojdiile ca aliment-medicament. In: Anghel I (ed). Biologia si Tehnologia Drojdiilor, vol 2, Editura Tehnica, Bucharest. Shieh CJ, Liao HF, Lee CC (2003). Optimization of lipase-catalyzed biodiesel by response surface methodology, Bioresour. Technol. 88: 103-106. Smigelschi O, Woinarovschy A (1978).

  1. Response surface method to optimize the low cost medium for ...

    African Journals Online (AJOL)

    A protease producing Bacillus sp. GA CAS10 was isolated from ascidian Phallusia arabica, Tuticorin, Southeast coast of India. Response surface methodology was employed for the optimization of different nutritional and physical factors for the production of protease. Plackett-Burman method was applied to identify ...

  2. Application of response surface methodology optimization for the ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-04-20

    Apr 20, 2009 ... of CQAs in tobacco waste were identified as three isomers containing chlorogenic acid (5-caffecylquinic acid ... Key words: Caffeic acid, caffeoylquinic acids (CQAs), hydrolysis reaction parameter optimization, response surface ..... Rosmarinic acid and caffeic acid produce antidepressive-like effect in.

  3. Response Surface Methodology's Steepest Ascent and Step Size Revisited

    NARCIS (Netherlands)

    Kleijnen, J.P.C.; den Hertog, D.; Angun, M.E.

    2002-01-01

    Response Surface Methodology (RSM) searches for the input combination maximizing the output of a real system or its simulation.RSM is a heuristic that locally fits first-order polynomials, and estimates the corresponding steepest ascent (SA) paths.However, SA is scale-dependent; and its step size is

  4. Surface functionalization of aluminosilicate nanotubes with organic molecules

    Directory of Open Access Journals (Sweden)

    Wei Ma

    2012-02-01

    Full Text Available The surface functionalization of inorganic nanostructures is an effective approach for enriching the potential applications of existing nanomaterials. Inorganic nanotubes attract great research interest due to their one-dimensional structure and reactive surfaces. In this review paper, recent developments in surface functionalization of an aluminosilicate nanotube, “imogolite”, are introduced. The functionalization processes are based on the robust affinity between phosphate groups of organic molecules and the aluminol (AlOH surface of imogolite nanotubes. An aqueous modification process employing a water soluble ammonium salt of alkyl phosphate led to chemisorption of molecules on imogolite at the nanotube level. Polymer-chain-grafted imogolite nanotubes were prepared through surface-initiated polymerization. In addition, the assembly of conjugated molecules, 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-ylethylphosphonic acid (HT3P and 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-ylethylphosphonic acid 1,1-dioxide (HT3OP, on the imogolite nanotube surface was achieved by introducing a phosphonic acid group to the corresponding molecules. The optical and photophysical properties of these conjugated-molecule-decorated imogolite nanotubes were characterized. Moreover, poly(3-hexylthiophene (P3HT chains were further hybridized with HT3P modified imogolite to form a nanofiber hybrid.

  5. Work function modifications of graphite surface via oxygen plasma treatment

    Science.gov (United States)

    Duch, J.; Kubisiak, P.; Adolfsson, K. H.; Hakkarainen, M.; Golda-Cepa, M.; Kotarba, A.

    2017-10-01

    The surface modification of graphite by oxygen plasma was investigated experimentally (X-ray diffraction, nanoparticle tracking analysis, laser desorption ionization mass spectrometry, thermogravimetry, water contact angle) and by molecular modelling (Density Functional Theory). Generation of surface functional groups (mainly sbnd OHsurf) leads to substantial changes in electrodonor properties and wettability gauged by work function and water contact angle, respectively. The invoked modifications were analyzed in terms of Helmholtz model taking into account the theoretically determined surface dipole moment of graphite-OHsurf system (μ = 2.71 D) and experimentally measured work function increase (from 0.75 to 1.02 eV) to determine the sbnd OH surface coverage (from 0.70 to 1.03 × 1014 groups cm-2). Since the plasma treatment was confined to the surface, the high thermal stability of the graphite material was preserved as revealed by the thermogravimetric analysis. The obtained results provide a suitable quantitative background for tuning the key operating parameters of carbon electrodes: electronic properties, interaction with water and thermal stability.

  6. Photo-responsive surface topology in chiral nematic media

    Science.gov (United States)

    Liu, Danqing; Bastiaansen, Cees W. M.; Toonder, Jaap. M. J.; Broer, Dirk J.

    2012-03-01

    We report on the design and fabrication of 'smart surfaces' that exhibit dynamic changes in their surface topology in response to exposure to light. The principle is based on anisotropic geometric changes of a liquid crystal network upon a change of the molecular order parameter. The photomechanical property of the coating is induced by incorporating an azobenzene moiety into the liquid crystal network. The responsive surface topology consists of regions with two different types of molecular order: planar chiral-nematic areas and homeotropic. Under flood exposure with 365 nm light the surfaces deform from flat to one with a surface relief. The height of the relief structures is of the order of 1 um corresponding to strain difference of around 20%. Furthermore, we demonstrate surface reliefs can form either convex or concave structures upon exposure to UV light corresponding to the decrease or increase molecular order parameter, respectively, related to the isomeric state of the azobenzene crosslinker. The reversible deformation to the initial flat state occurs rapidly after removing the light source.

  7. Inverse modeling of cloud-aerosol interactions -- Part 1: Detailed response surface analysis

    NARCIS (Netherlands)

    Partridge, D.G.; Vrugt, J.A.; Tunved, P.; Ekman, A.M.L.; Gorea, D.; Sooroshian, A.

    2011-01-01

    New methodologies are required to probe the sensitivity of parameters describing cloud droplet activation. This paper presents an inverse modeling-based method for exploring cloud-aerosol interactions via response surfaces. The objective function, containing the difference between the measured and

  8. Osteoblast response to oxygen functionalised plasma polymer surfaces

    International Nuclear Information System (INIS)

    Kelly, Jonathan M.

    2001-01-01

    Thin organic films with oxygen-carbon functionalities were deposited from plasmas containing vapour of the small organic compounds: allyI alcohol, methyl vinyl ketone and acrylic acid with octadiene. Characterisation of the deposits was carried out using X-ray photoelectron spectroscopy, in conjunction with chemical derivatisation, and this showed that plasma polymers retained high levels of original monomer functionality when the plasmas were sustained at low power for a given monomer vapour flow rate. High levels of attachment of rat osteosarcoma (ROS 17/2.8) cells were observed on surfaces that had high concentrations of hydroxyl and carbonyl functionalities and intermediate concentrations of carboxyl functionality. Cells did not attach to the octadiene plasma polymer. Cell attachment to carboxyl and methyl functionalised self-assembled monolayers increased with increasing concentration of surface carboxyl groups. Adsorption of the extracellular matrix protein fibronectin to acrylic acid/octadiene plasma copolymers was studied by enzyme linked immunosorbent assays and by I 125 radiolabelling. Fibronectin adsorbed in largest amounts to surfaces with intermediate concentrations of carboxyl functionality. Spreading of ROS cells and rat bone marrow stromal cells (BMSC) was characterised by computer image analysis. Cell spreading in media containing 10% serum, on a surface deposited from a plasma of 5 O/o acrylic acid was much greater than on the octadiene plasma polymer while most extensive cell spreading was observed on these surfaces when preadsorbed with fibronectin. Growth (proliferation) of BMSC was assessed over nine days and was found to be faster on an 50% acrylic acid plasma polymer than on tissue culture polystyrene or a hydrocarbon plasma polymer, though cell growth was fastest on fibronectin precoated substrates. Expression of cellular alkaline phosphatase, collagen and calcium reached similar levels on the 50% acrylic acid plasma polymer, tissue culture

  9. Osteoblast response to oxygen functionalised plasma polymer surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Jonathan M

    2001-07-01

    Thin organic films with oxygen-carbon functionalities were deposited from plasmas containing vapour of the small organic compounds: allyI alcohol, methyl vinyl ketone and acrylic acid with octadiene. Characterisation of the deposits was carried out using X-ray photoelectron spectroscopy, in conjunction with chemical derivatisation, and this showed that plasma polymers retained high levels of original monomer functionality when the plasmas were sustained at low power for a given monomer vapour flow rate. High levels of attachment of rat osteosarcoma (ROS 17/2.8) cells were observed on surfaces that had high concentrations of hydroxyl and carbonyl functionalities and intermediate concentrations of carboxyl functionality. Cells did not attach to the octadiene plasma polymer. Cell attachment to carboxyl and methyl functionalised self-assembled monolayers increased with increasing concentration of surface carboxyl groups. Adsorption of the extracellular matrix protein fibronectin to acrylic acid/octadiene plasma copolymers was studied by enzyme linked immunosorbent assays and by I{sup 125} radiolabelling. Fibronectin adsorbed in largest amounts to surfaces with intermediate concentrations of carboxyl functionality. Spreading of ROS cells and rat bone marrow stromal cells (BMSC) was characterised by computer image analysis. Cell spreading in media containing 10% serum, on a surface deposited from a plasma of 5 O/o acrylic acid was much greater than on the octadiene plasma polymer while most extensive cell spreading was observed on these surfaces when preadsorbed with fibronectin. Growth (proliferation) of BMSC was assessed over nine days and was found to be faster on an 50% acrylic acid plasma polymer than on tissue culture polystyrene or a hydrocarbon plasma polymer, though cell growth was fastest on fibronectin precoated substrates. Expression of cellular alkaline phosphatase, collagen and calcium reached similar levels on the 50% acrylic acid plasma polymer, tissue

  10. The sewing technique and correlation functions on arbitrary Riemann surfaces

    International Nuclear Information System (INIS)

    Di Vecchia, P.

    1989-01-01

    We describe in the case of free bosonic and fermionic theories the sewing procedure, that is a very convenient way for constructing correlation functions of these theories on an arbitrary Riemann surface from their knowledge on the sphere. The fundamental object that results from this construction is the N-point g-loop vertex. It summarizes the information of all correlation functions of the theory on an arbitrary Riemann surface. We then check explicitly the bosonization rules and derive some useful formulas. (orig.)

  11. Kinetic-energy functionals studied by surface calculations

    DEFF Research Database (Denmark)

    Vitos, Levente; Skriver, Hans Lomholt; Kollár, J.

    1998-01-01

    The self-consistent jellium model of metal surfaces is used to study the accuracy of a number of semilocal kinetic-energy functionals for independent particles. It is shown that the poor accuracy exhibited by the gradient expansion approximation and most of the semiempirical functionals in the lo...... density, high gradient limit may be subtantially improved by including locally a von Weizsacker term. Based on this, we propose a simple one-parameter Pade's approximation, which reproduces the exact Kohn-Sham surface kinetic energy over the entire range of metallic densities....

  12. Overview on the Surface Functionalization Mechanism and Determination of Surface Functional Groups of Plasma Treated Carbon Nanotubes.

    Science.gov (United States)

    Saka, Cafer

    2018-01-02

    The use of carbon materials for many applications is due to the unique diversity of structures and properties ranging from chemical bonds between the carbon atoms of the materials to nanostructures, crystallite alignment, and microstructures. Carbon nanotubes and other nanoscale carbonaceous materials draw much attention due to their physical and chemical properties, such as high strength, high resistance to corrosion, electrical and thermal conductivity, stability and a qualified adsorbent. Carbon-based nanomaterials, which have a relatively large specific area and layered structure, can be used as an adsorbent for efficient removal of organic and inorganic contaminants. However, one of the biggest obstacles to the development of carbon-based nanomaterials adsorbents is insolubility and the lack of functional groups on the surface. There are several approaches to introduce functional groups on carbon nanotubes. One of these approaches, plasma applications, now has an important place in the creation of surface functional groups as a flexible, fast, and environmentally friendly method. This review focuses on recent information concerning the surface functionalization and modification of plasma treated carbon nanotube. This review considers the surface properties, advantages, and disadvantages of plasma-applied carbon nanotubes. It also examines the reaction mechanisms involved in the functional groups on the surface.

  13. Response mechanism for surface acoustic wave gas sensors based on surface-adsorption.

    Science.gov (United States)

    Liu, Jiansheng; Lu, Yanyan

    2014-04-16

    A theoretical model is established to describe the response mechanism of surface acoustic wave (SAW) gas sensors based on physical adsorption on the detector surface. Wohljent's method is utilized to describe the relationship of sensor output (frequency shift of SAW oscillator) and the mass loaded on the detector surface. The Brunauer-Emmett-Teller (BET) formula and its improved form are introduced to depict the adsorption behavior of gas on the detector surface. By combining the two methods, we obtain a theoretical model for the response mechanism of SAW gas sensors. By using a commercial SAW gas chromatography (GC) analyzer, an experiment is performed to measure the frequency shifts caused by different concentration of dimethyl methylphosphonate (DMMP). The parameters in the model are given by fitting the experimental results and the theoretical curve agrees well with the experimental data.

  14. Direct quantification of negatively charged functional groups on membrane surfaces

    KAUST Repository

    Tiraferri, Alberto

    2012-02-01

    Surface charge plays an important role in membrane-based separations of particulates, macromolecules, and dissolved ionic species. In this study, we present two experimental methods to determine the concentration of negatively charged functional groups at the surface of dense polymeric membranes. Both techniques consist of associating the membrane surface moieties with chemical probes, followed by quantification of the bound probes. Uranyl acetate and toluidine blue O dye, which interact with the membrane functional groups via complexation and electrostatic interaction, respectively, were used as probes. The amount of associated probes was quantified using liquid scintillation counting for uranium atoms and visible light spectroscopy for the toluidine blue dye. The techniques were validated using self-assembled monolayers of alkanethiols with known amounts of charged moieties. The surface density of negatively charged functional groups of hand-cast thin-film composite polyamide membranes, as well as commercial cellulose triacetate and polyamide membranes, was quantified under various conditions. Using both techniques, we measured a negatively charged functional group density of 20-30nm -2 for the hand-cast thin-film composite membranes. The ionization behavior of the membrane functional groups, determined from measurements with toluidine blue at varying pH, was consistent with published data for thin-film composite polyamide membranes. Similarly, the measured charge densities on commercial membranes were in general agreement with previous investigations. The relative simplicity of the two methods makes them a useful tool for quantifying the surface charge concentration of a variety of surfaces, including separation membranes. © 2011 Elsevier B.V.

  15. Improved density functional calculations for atoms, molecules and surfaces

    International Nuclear Information System (INIS)

    Fricke, B.; Anton, J.; Fritzsche, S.; Sarpe-Tudoran, C.

    2005-01-01

    The non-collinear and collinear descriptions within relativistic density functional theory is described. We present results of both non-collinear and collinear calculations for atoms, diatomic molecules, and some surface simulations. We find that the accuracy of our density functional calculations for the smaller systems is comparable to good quantum chemical calculations, and thus this method provides a sound basis for larger systems where no such comparison is possible. (author)

  16. Surface modification influencing adsorption of red wine constituents: The role of functional groups

    Science.gov (United States)

    Mierczynska-Vasilev, Agnieszka; Smith, Paul A.

    2016-11-01

    The adsorption of wine constituents at solid surfaces is important in applications such as filtration and membrane fouling, binding to tanks and fittings and interactions with processing aids such as bentonite. The interaction of wine constituents with surfaces is mediated through adsorbed wine components, where the type of constituents, amount, orientation, and conformation are of consequence for the surface response. This study examines the effect of surface chemical functionalities on the adsorption of red wine constituents. Plasma-polymerized films rich in amine, carboxyl, hydroxyl, formyl and methyl functional groups were generated on solid substrates whereas, glycidyltrimethylammonium chloride was covalently attached to allylamine plasma-polymer modified surface and poly(sodium styrenesulfonate) was electrostatically adsorbed to an amine plasma-polymerized surface. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy. The ability of different substrates to adsorb red wine constituents was evaluated by quartz crystal microbalance and atomic force microscopy. The results showed that substrates modified with -SO3H and -COOH groups can adsorb more of the wine nitrogen-containing compounds whereas -NH2 and -NR3 groups encourage carbon-containing compounds adsorption. Red wine constituents after filtration were adsorbed in higher extend on -NR3 and -CHO surfaces. The -OH modified surfaces had the lowest ability to absorb wine components.

  17. Response function of a p type - HPGe detector

    International Nuclear Information System (INIS)

    Lopez-Pino, Neivy; Cabral, Fatima Padilla; D'Alessandro, Katia; Maidana, Nora Lia; Vanin, Vito Roberto

    2011-01-01

    The response function of a HPGe detector depends on Ge crystal dimensions and dead layers thicknesses; most of them are not given by the manufacturers or change with detector damage from neutrons or contact with the atmosphere and therefore must be experimentally determined. The response function is obtained by a Monte-Carlo simulation procedure based on the Ge crystal characteristics. In this work, a p-type coaxial HPGe detector with 30% efficiency, manufactured in 1989, was investigated. The crystal radius and length and the inner hole dimensions were obtained scanning the capsule both in the radial and axial directions using 4 mm collimated beams from 137 Cs, 207 Bi point sources placed on a x-y table in steps of 2,00 mm. These dimensions were estimated comparing the experimental peak areas with those obtained by simulation using several hole configurations. In a similar procedure, the frontal dead layer thickness was determined using 2 mm collimated beams of the 59 keV gamma-rays from 241 Am and 81 keV from 133 Ba sources hitting the detector at 90 deg and 45 deg with respect to the capsule surface. The Monte Carlo detector model included, besides the crystal, hole and capsules sizes, the Ge dead-layers. The obtained spectra were folded with a gaussian resolution function to account for electronic noise. The comparison of simulated and experimental response functions for 4 mm collimated beams of 60 Co, 137 Cs, and 207 Bi points sources placed at distances of 7, 11 and 17 cm from the detector end cap showed relative deviations of about 10% in general and below 10% in the peak. The frontal dead layer thickness determined by our procedure was different from that specified by the detector manufacturer. (author)

  18. Protein-surface interactions on stimuli-responsive polymeric biomaterials.

    Science.gov (United States)

    Cross, Michael C; Toomey, Ryan G; Gallant, Nathan D

    2016-03-04

    Responsive surfaces: a review of the dependence of protein adsorption on the reversible volume phase transition in stimuli-responsive polymers. Specifically addressed are a widely studied subset: thermoresponsive polymers. Findings are also generalizable to other materials which undergo a similarly reversible volume phase transition. As of 2015, over 100,000 articles have been published on stimuli-responsive polymers and many more on protein-biomaterial interactions. Significantly, fewer than 100 of these have focused specifically on protein interactions with stimuli-responsive polymers. These report a clear trend of increased protein adsorption in the collapsed state compared to the swollen state. This control over protein interactions makes stimuli-responsive polymers highly useful in biomedical applications such as wound repair scaffolds, on-demand drug delivery, and antifouling surfaces. Outstanding questions are whether the protein adsorption is reversible with the volume phase transition and whether there is a time-dependence. A clear understanding of protein interactions with stimuli-responsive polymers will advance theoretical models, experimental results, and biomedical applications.

  19. Molecular recognition on a cavitand-functionalized silicon surface.

    Science.gov (United States)

    Biavardi, Elisa; Favazza, Maria; Motta, Alessandro; Fragalà, Ignazio L; Massera, Chiara; Prodi, Luca; Montalti, Marco; Melegari, Monica; Condorelli, Guglielmo G; Dalcanale, Enrico

    2009-06-03

    A Si(100) surface featuring molecular recognition properties was obtained by covalent functionalization with a tetraphosphonate cavitand (Tiiii), able to complex positively charged species. Tiiii cavitand was grafted onto the Si by photochemical hydrosilylation together with 1-octene as a spatial spectator. The recognition properties of the Si-Tiiii surface were demonstrated through two independent analytical techniques, namely XPS and fluorescence spectroscopy, during the course of reversible complexation-guest exchange-decomplexation cycles with specifically designed ammonium and pyridinium salts. Control experiments employing a Si(100) surface functionalized with a structurally similar, but complexation inactive, tetrathiophosphonate cavitand (TSiiii) demonstrated no recognition events. This provides evidence for the complexation properties of the Si-Tiiii surface, ruling out the possibility of nonspecific interactions between the substrate and the guests. The residual Si-O(-) terminations on the surface replace the guests' original counterions, thus stabilizing the complex ion pairs. These results represent a further step toward the control of self-assembly of complex supramolecular architectures on surfaces.

  20. Orthogonal functionalization of nanoporous substrates: control of 3D surface functionality.

    Science.gov (United States)

    Lazzara, Thomas D; Kliesch, Torben-Tobias; Janshoff, Andreas; Steinem, Claudia

    2011-04-01

    Anodic aluminum oxide (AAO) membranes with aligned, cylindrical, nonintersecting pores were selectively functionalized in order to create dual-functionality substrates with different pore-rim and pore-interior surface functionalities, using silane chemistry. We used a two-step process involving an evaporated thin gold film to protect the underlying surface functionality of the pore rims. Subsequent treatment with oxygen plasma of the modified AAO membrane removed the unprotected organic functional groups, i.e., the pore-interior surface. After gold removal, the substrate became optically transparent, and displayed two distinct surface functionalities, one at the pore-rim surface and another at the pore-interior surface. We achieved a selective hydrophobic functionalization with dodecyl-trichlorosilane of either the pore rims or the pore interiors. The deposition of planar lipid membranes on the functionalized areas by addition of small unilamellar vesicles occurred in a predetermined fashion. Small unilamellar vesicles only ruptured upon contact with the hydrophobic substrate regions forming solid supported hybrid bilayers. In addition, pore-rim functionalization with dodecyl-trichlorosilane allowed the formation of pore-spanning hybrid lipid membranes as a result of giant unilamellar vesicle rupture. Confocal laser scanning microscopy was employed to identify the selective spatial localization of the adsorbed fluorescently labeled lipids. The corresponding increase in the AAO refractive index due to lipid adsorption on the hydrophobic regions was monitored by optical waveguide spectroscopy. This simple orthogonal functionalization route is a promising method to control the three-dimensional surface functionality of nanoporous films. © 2011 American Chemical Society

  1. Density functional theory in surface science and heterogeneous catalysis

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet; Scheffler, M.; Toulhoat, H.

    2006-01-01

    Solid surfaces are used extensively as catalysts throughout the chemical industry, in the energy sector, and in environmental protection. Recently, density functional theory has started providing new insight into the atomic-scale mechanisms of heterogeneous catalysis, helping to interpret the large...

  2. Membrane mimetic surface functionalization of nanoparticles: Methods and applications

    Science.gov (United States)

    Weingart, Jacob; Vabbilisetty, Pratima; Sun, Xue-Long

    2013-01-01

    Nanoparticles (NPs), due to their size-dependent physical and chemical properties, have shown remarkable potential for a wide range of applications over the past decades. Particularly, the biological compatibilities and functions of NPs have been extensively studied for expanding their potential in areas of biomedical application such as bioimaging, biosensing, and drug delivery. In doing so, surface functionalization of NPs by introducing synthetic ligands and/or natural biomolecules has become a critical component in regards to the overall performance of the NP system for its intended use. Among known examples of surface functionalization, the construction of an artificial cell membrane structure, based on phospholipids, has proven effective in enhancing biocompatibility and has become a viable alternative to more traditional modifications, such as direct polymer conjugation. Furthermore, certain bioactive molecules can be immobilized onto the surface of phospholipid platforms to generate displays more reminiscent of cellular surface components. Thus, NPs with membrane-mimetic displays have found use in a range of bioimaging, biosensing, and drug delivery applications. This review herein describes recent advances in the preparations and characterization of integrated functional NPs covered by artificial cell membrane structures and their use in various biomedical applications. PMID:23688632

  3. Radial Basis Function Based Quadrature over Smooth Surfaces

    Science.gov (United States)

    2016-03-24

    Radial Basis Functions φ(r) Piecewise Smooth (Conditionally Positive Definite) MN Monomial |r|2m+1 TPS thin plate spline |r|2mln|r| Infinitely Smooth...smooth surfaces using polynomial interpolants, while [27] couples Thin - Plate Spline interpolation (see table 1) with Green’s integral formula [29

  4. Designing Pulse Laser Surface Modification of H13 Steel Using Response Surface Method

    Science.gov (United States)

    Aqida, S. N.; Brabazon, D.; Naher, S.

    2011-01-01

    This paper presents a design of experiment (DOE) for laser surface modification process of AISI H13 tool steel in achieving the maximum hardness and minimum surface roughness at a range of modified layer depth. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). The response surface method with Box-Behnken design approach in Design Expert 7 software was used to design the H13 laser surface modification process. Metallographic study and image analysis were done to measure the modified layer depth. The modified surface roughness was measured using two-dimensional surface profilometer. The correlation of the three laser processing parameters and the modified surface properties was specified by plotting three-dimensional graph. The hardness properties were tested at 981 mN force. From metallographic study, the laser modified surface depth was between 37 μm and 150 μm. The average surface roughness recorded from the 2D profilometry was at a minimum value of 1.8 μm. The maximum hardness achieved was between 728 and 905 HV0.1. These findings are significant to modern development of hard coatings for wear resistant applications.

  5. Response surface optimisation for activation of bentonite with microwave irradiation

    Directory of Open Access Journals (Sweden)

    Rožić Ljiljana S.

    2011-01-01

    Full Text Available In this study, the statistical design of the experimental method was applied on the acid activation process of bentonite with microwave irradiation. The influence of activation parameters (time, acid normality and microwave heating power on the selected process response of the activated bentonite samples was studied. The specific surface area was chosen for the process response, because the chemical, surface and structural properties of the activated clay determine and limit its potential applications. The relationship of various process parameters with the specific surface area of bentonite was examined. A mathematical model was developed using a second-order response surface model (RSM with a central composite design incorporating the above mentioned process parameters. The mathematical model developed helped in predicting the variation in specific surface area of activated bentonite with time (5-21 min, acid normality (2-7 N and microwave heating power (63-172 W. The calculated regression models were found to be statistically significant at the required range and presented little variability. Furthermore, high values of R2 (0.957 and R2 (adjusted (0.914 indicate a high dependence and correlation between the observed and the predicted values of the response. These high values also indicate that about 96% of the result of the total variation can be explained by this model. In addition, the model shows that increasing the time and acid normality improves the textural properties of bentonites, resulting in increased specific surface area. This model also can be useful for setting an optimum value of the activation parameters for achieving the maximum specific surface area. An optimum specific surface area of 142 m2g-1 was achieved with an acid normality of 5.2 N, activation time of 7.38 min and microwave power of 117 W. Acid activation of bentonite was found to occur faster with microwave irradiation than with conventional heating. Microwave

  6. Scattering function for a model of interacting surfaces

    International Nuclear Information System (INIS)

    Colangelo, P.; Gonnella, G.; Maritan, A.

    1993-01-01

    The two-point correlation function of an ensemble of interacting closed self-avoiding surfaces on a cubic lattice is analyzed in the disordered phase, which corresponds to the paramagnetic region in a related spin formulation. Mean-field theory and Monte Carlo simulations predict the existence of a disorder line which corresponds to a transition from an exponential decay to an oscillatory damped behavior of the two-point correlation function. The relevance of the results for the description of amphiphilic systems in a microemulsion phase is discussed. The scattering function is also calculated for a bicontinuous phase coexisting with the paramagnetic phase

  7. Surface functionalization of detonation nanodiamonds by phosphonic dichloride derivatives.

    Science.gov (United States)

    Presti, Charlene; Alauzun, Johan G; Laurencin, Danielle; Mutin, P Hubert

    2014-08-05

    A new method for the functionalization of detonation nanodiamonds (DNDs) is proposed, on the basis of surface modification with phosphonic dichloride derivatives. DNDs were first modified by phenylphosphonic dichloride, and the grafting modes and hydrolytic stability under neutral conditions were investigated using (1)H, (13)C, and (31)P solid state NMR spectroscopy, Fourier transform infrared spectroscopy, as well as elemental analysis. Then, in order to illustrate the possibilities offered by this method, DNDs functionalized by mesityl imidazolium groups were obtained by postmodification of DNDs modified by 12-bromododecylphosphonic dichloride. The oxidative thermal stability of the functionalized DNDs was investigated using thermogravimetric analysis.

  8. Evolution of the transfer function characterization of surface scatter phenomena

    Science.gov (United States)

    Harvey, James E.; Pfisterer, Richard N.

    2016-09-01

    Based upon the empirical observation that BRDF measurements of smooth optical surfaces exhibited shift-invariant behavior when plotted versus    o , the original Harvey-Shack (OHS) surface scatter theory was developed as a scalar linear systems formulation in which scattered light behavior was characterized by a surface transfer function (STF) reminiscent of the optical transfer function (OTF) of modern image formation theory (1976). This shift-invariant behavior combined with the inverse power law behavior when plotting log BRDF versus log   o was quickly incorporated into several optical analysis software packages. Although there was no explicit smooth-surface approximation in the OHS theory, there was a limitation on both the incident and scattering angles. In 1988 the modified Harvey-Shack (MHS) theory removed the limitation on the angle of incidence; however, a moderate-angle scattering limitation remained. Clearly for large incident angles the BRDF was no longer shift-invariant as a different STF was now required for each incident angle. In 2011 the generalized Harvey-Shack (GHS) surface scatter theory, characterized by a two-parameter family of STFs, evolved into a practical modeling tool to calculate BRDFs from optical surface metrology data for situations that violate the smooth surface approximation inherent in the Rayleigh-Rice theory and/or the moderate-angle limitation of the Beckmann-Kirchhoff theory. And finally, the STF can be multiplied by the classical OTF to provide a complete linear systems formulation of image quality as degraded by diffraction, geometrical aberrations and surface scatter effects from residual optical fabrication errors.

  9. Response of fuzzy tungsten surfaces to pulsed plasma bombardment

    International Nuclear Information System (INIS)

    Nishijima, D.; Doerner, R.P.; Iwamoto, D.; Kikuchi, Y.; Miyamoto, M.; Nagata, M.; Sakuma, I.; Shoda, K.; Ueda, Y.

    2013-01-01

    Damage of fuzzy tungsten surfaces due to a transient plasma load is characterized in terms of mass loss, surface morphology, and optical properties. A single D pulsed (∼0.1–0.2 ms) plasma shot with surface absorbed energy density of ∼1.1 MJ m −2 leads to a mass loss of ∼80 μg, which cannot be explained by physical sputtering. Thus, macroscopic erosion processes such as droplets and dust release as well as arcing are thought to be responsible for the mass loss. In fact, scanning electron microscopy observations reveal the melting of the tips of fuzz and arc tracks. The optical reflectivity of the damaged (melted) surface is measured to be higher than that of an undamaged fuzzy surface (below ∼0.01%). Spectroscopic ellipsometry shows that the refractive index, n, and extinction coefficient, k, increase from n ≈ 1 and k ≈ 0 for an undamaged fuzzy surface with an increase in the degree of damage of fuzz

  10. Semi-classical calculation of the spin-isospin response functions

    International Nuclear Information System (INIS)

    Chanfray, G.

    1987-03-01

    We present a semi-classical calculation of the nuclear response functions beyond the Thomas-Fermi approximation. We apply our formalism to the spin-isospin responses and show that the surface peaked h/2π corrections considerably decrease the ratio longitudinal/transverse as obtained through hadronic probes

  11. Minimal models on Riemann surfaces: The partition functions

    International Nuclear Information System (INIS)

    Foda, O.

    1990-01-01

    The Coulomb gas representation of the A n series of c=1-6/[m(m+1)], m≥3, minimal models is extended to compact Riemann surfaces of genus g>1. An integral representation of the partition functions, for any m and g is obtained as the difference of two gaussian correlation functions of a background charge, (background charge on sphere) x (1-g), and screening charges integrated over the surface. The coupling constant x (compacitification radius) 2 of the gaussian expressions are, as on the torus, m(m+1), and m/(m+1). The partition functions obtained are modular invariant, have the correct conformal anomaly and - restricting the propagation of states to a single handle - one can verify explicitly the decoupling of the null states. On the other hand, they are given in terms of coupled surface integrals, and it remains to show how they degenerate consistently to those on lower-genus surfaces. In this work, this is clear only at the lattice level, where no screening charges appear. (orig.)

  12. Minimal models on Riemann surfaces: The partition functions

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O. (Katholieke Univ. Nijmegen (Netherlands). Inst. voor Theoretische Fysica)

    1990-06-04

    The Coulomb gas representation of the A{sub n} series of c=1-6/(m(m+1)), m{ge}3, minimal models is extended to compact Riemann surfaces of genus g>1. An integral representation of the partition functions, for any m and g is obtained as the difference of two gaussian correlation functions of a background charge, (background charge on sphere) x (1-g), and screening charges integrated over the surface. The coupling constant x (compacitification radius){sup 2} of the gaussian expressions are, as on the torus, m(m+1), and m/(m+1). The partition functions obtained are modular invariant, have the correct conformal anomaly and - restricting the propagation of states to a single handle - one can verify explicitly the decoupling of the null states. On the other hand, they are given in terms of coupled surface integrals, and it remains to show how they degenerate consistently to those on lower-genus surfaces. In this work, this is clear only at the lattice level, where no screening charges appear. (orig.).

  13. Silver nanoprisms self-assembly on differently functionalized silica surface

    International Nuclear Information System (INIS)

    Pilipavicius, J; Chodosovskaja, A; Beganskiene, A; Kareiva, A

    2015-01-01

    In this work colloidal silica/silver nanoprisms (NPRs) composite coatings were made. Firstly colloidal silica sols were synthesized by sol-gel method and produced coatings on glass by dip-coating technique. Next coatings were silanized by (3-Aminopropyl)triethoxysilane (APTES), N-[3-(Trimethoxysilyl)propyl]ethylenediamine (AEAPTMS), (3- Mercaptopropyl)trimethoxysilane (MPTMS). Silver NPRs where synthesized via seed-mediated method and high yield of 94±15 nm average edge length silver NPRs were obtained with surface plasmon resonance peak at 921 nm. Silica-Silver NPRs composite coatings obtained by selfassembly on silica coated-functionalized surface. In order to find the most appropriate silanization way for Silver NPRs self-assembly, the composite coatings were characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), water contact angle (CA) and surface free energy (SFE) methods. Results have showed that surface functionalization is necessary to achieve self-assembled Ag NPRs layer. MPTMS silanized coatings resulted sparse distribution of Ag NPRs. Most homogeneous, even distribution composite coatings obtained on APTES functionalized silica coatings, while AEAPTMS induced strong aggregation of Silver NPRs

  14. Surface interpolation with radial basis functions for medical imaging

    International Nuclear Information System (INIS)

    Carr, J.C.; Beatson, R.K.; Fright, W.R.

    1997-01-01

    Radial basis functions are presented as a practical solution to the problem of interpolating incomplete surfaces derived from three-dimensional (3-D) medical graphics. The specific application considered is the design of cranial implants for the repair of defects, usually holes, in the skull. Radial basis functions impose few restrictions on the geometry of the interpolation centers and are suited to problems where interpolation centers do not form a regular grid. However, their high computational requirements have previously limited their use to problems where the number of interpolation centers is small (<300). Recently developed fast evaluation techniques have overcome these limitations and made radial basis interpolation a practical approach for larger data sets. In this paper radial basis functions are fitted to depth-maps of the skull's surface, obtained from X-ray computed tomography (CT) data using ray-tracing techniques. They are used to smoothly interpolate the surface of the skull across defect regions. The resulting mathematical description of the skull's surface can be evaluated at any desired resolution to be rendered on a graphics workstation or to generate instructions for operating a computer numerically controlled (CNC) mill

  15. Surface functional groups in capacitive deionization with porous carbon electrodes

    Science.gov (United States)

    Hemmatifar, Ali; Oyarzun, Diego I.; Palko, James W.; Hawks, Steven A.; Stadermann, Michael; Santiago, Juan G.; Stanford Microfluidics Lab Team; Lawrence Livermore National Lab Team

    2017-11-01

    Capacitive deionization (CDI) is a promising technology for removal of toxic ions and salt from water. In CDI, an applied potential of about 1 V to pairs of porous electrodes (e.g. activated carbon) induces ion electromigration and electrostatic adsorption at electrode surfaces. Immobile surface functional groups play a critical role in the type and capacity of ion adsorption, and this can dramatically change desalination performance. We here use models and experiments to study weak electrolyte surface groups which protonate and/or depropotante based on their acid/base dissociation constants and local pore pH. Net chemical surface charge and differential capacitance can thus vary during CDI operation. In this work, we present a CDI model based on weak electrolyte acid/base equilibria theory. Our model incorporates preferential cation (anion) adsorption for activated carbon with acidic (basic) surface groups. We validated our model with experiments on custom built CDI cells with a variety of functionalizations. To this end, we varied electrolyte pH and measured adsorption of individual anionic and cationic ions using inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography (IC) techniques. Our model shows good agreement with experiments and provides a framework useful in the design of CDI control schemes.

  16. Plant surface wax affects parasitoid's response to host footprints

    Science.gov (United States)

    Rostás, Michael; Ruf, Daniel; Zabka, Vanessa; Hildebrandt, Ulrich

    2008-10-01

    The plant surface is the substrate upon which herbivorous insects and natural enemies meet and thus represents the stage for interactions between the three trophic levels. Plant surfaces are covered by an epicuticular wax layer which is highly variable depending on species, cultivar or plant part. Differences in wax chemistry may modulate ecological interactions. We explored whether caterpillars of Spodoptera frugiperda, when walking over a plant surface, leave a chemical trail (kairomones) that can be detected by the parasitoid Cotesia marginiventris. Chemistry and micromorphology of cuticular waxes of two barley eceriferum wax mutants ( cer-za.126, cer-yp.949) and wild-type cv. Bonus (wt) were assessed. The plants were then used to investigate potential surface effects on the detectability of caterpillar kairomones. Here we provide evidence that C. marginiventris responds to chemical footprints of its host. Parasitoids were able to detect the kairomone on wild-type plants and on both cer mutants but the response to cer-yp.949 (reduced wax, high aldehyde fraction) was less pronounced. Experiments with caterpillar-treated wt and mutant leaves offered simultaneously, confirmed this observation: no difference in wasp response was found when wt was tested against cer-za.126 (reduced wax, wt-like chemical composition) but wt was significantly more attractive than cer-yp.949. This demonstrates for the first time that the wax layer can modulate the detectability of host kairomones.

  17. Simulation of ecological processes using response functions method

    International Nuclear Information System (INIS)

    Malkina-Pykh, I.G.; Pykh, Yu. A.

    1998-01-01

    The article describes further development and applications of the already well-known response functions method (MRF). The method is used as a basis for the development of mathematical models of a wide set of ecological processes. The model of radioactive contamination of the ecosystems is chosen as an example. The mathematical model was elaborated for the description of 90 Sr dynamics in the elementary ecosystems of various geographical zones. The model includes the blocks corresponding with the main units of any elementary ecosystem: lower atmosphere, soil, vegetation, surface water. Parameters' evaluation was provided on a wide set of experimental data. A set of computer simulations was done on the model to prove the possibility of the model's use for ecological forecasting

  18. SURFACE SYMMETRY ENERGY OF NUCLEAR ENERGY DENSITY FUNCTIONALS

    Energy Technology Data Exchange (ETDEWEB)

    Nikolov, N; Schunck, N; Nazarewicz, W; Bender, M; Pei, J

    2010-12-20

    We study the bulk deformation properties of the Skyrme nuclear energy density functionals. Following simple arguments based on the leptodermous expansion and liquid drop model, we apply the nuclear density functional theory to assess the role of the surface symmetry energy in nuclei. To this end, we validate the commonly used functional parametrizations against the data on excitation energies of superdeformed band-heads in Hg and Pb isotopes, and fission isomers in actinide nuclei. After subtracting shell effects, the results of our self-consistent calculations are consistent with macroscopic arguments and indicate that experimental data on strongly deformed configurations in neutron-rich nuclei are essential for optimizing future nuclear energy density functionals. The resulting survey provides a useful benchmark for further theoretical improvements. Unlike in nuclei close to the stability valley, whose macroscopic deformability hangs on the balance of surface and Coulomb terms, the deformability of neutron-rich nuclei strongly depends on the surface-symmetry energy; hence, its proper determination is crucial for the stability of deformed phases of the neutron-rich matter and description of fission rates for r-process nucleosynthesis.

  19. Multi-Functional Stimuli-Responsive Materials

    Data.gov (United States)

    National Aeronautics and Space Administration — Supramolecular polymers based on non-covalent interactions can display a wide array of stimuli-responsive attributes. They can be tailored to change shape, actuate...

  20. Aryl Diazonium Chemistry for the Surface Functionalization of Glassy Biosensors

    Directory of Open Access Journals (Sweden)

    Wei Zheng

    2016-03-01

    Full Text Available Nanostring resonator and fiber-optics-based biosensors are of interest as they offer high sensitivity, real-time measurements and the ability to integrate with electronics. However, these devices are somewhat impaired by issues related to surface modification. Both nanostring resonators and photonic sensors employ glassy materials, which are incompatible with electrochemistry. A surface chemistry approach providing strong and stable adhesion to glassy surfaces is thus required. In this work, a diazonium salt induced aryl film grafting process is employed to modify a novel SiCN glassy material. Sandwich rabbit IgG binding assays are performed on the diazonium treated SiCN surfaces. Fluorescently labelled anti-rabbit IgG and anti-rabbit IgG conjugated gold nanoparticles were used as markers to demonstrate the absorption of anti-rabbit IgG and therefore verify the successful grafting of the aryl film. The results of the experiments support the effectiveness of diazonium chemistry for the surface functionalization of SiCN surfaces. This method is applicable to other types of glassy materials and potentially can be expanded to various nanomechanical and optical biosensors.

  1. Aryl Diazonium Chemistry for the Surface Functionalization of Glassy Biosensors.

    Science.gov (United States)

    Zheng, Wei; van den Hurk, Remko; Cao, Yong; Du, Rongbing; Sun, Xuejun; Wang, Yiyu; McDermott, Mark T; Evoy, Stephane

    2016-03-14

    Nanostring resonator and fiber-optics-based biosensors are of interest as they offer high sensitivity, real-time measurements and the ability to integrate with electronics. However, these devices are somewhat impaired by issues related to surface modification. Both nanostring resonators and photonic sensors employ glassy materials, which are incompatible with electrochemistry. A surface chemistry approach providing strong and stable adhesion to glassy surfaces is thus required. In this work, a diazonium salt induced aryl film grafting process is employed to modify a novel SiCN glassy material. Sandwich rabbit IgG binding assays are performed on the diazonium treated SiCN surfaces. Fluorescently labelled anti-rabbit IgG and anti-rabbit IgG conjugated gold nanoparticles were used as markers to demonstrate the absorption of anti-rabbit IgG and therefore verify the successful grafting of the aryl film. The results of the experiments support the effectiveness of diazonium chemistry for the surface functionalization of SiCN surfaces. This method is applicable to other types of glassy materials and potentially can be expanded to various nanomechanical and optical biosensors.

  2. Development of measurement standards for verifying functional performance of surface texture measuring instruments

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, A [Life and Industrial Product Development Department Olympus Corporation, 2951 Ishikawa-machi, Hachiouji-shi, Tokyo (Japan); Suzuki, H [Industrial Marketing and Planning Department Olympus Corporation, Shinjyuku Monolith, 3-1 Nishi-Shinjyuku 2-chome, Tokyo (Japan); Yanagi, K, E-mail: a_fujii@ot.olympus.co.jp [Department of Mechanical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka-machi, Nagaoka-shi, Niigata (Japan)

    2011-08-19

    A new measurement standard is proposed for verifying overall functional performance of surface texture measuring instruments. Its surface is composed of sinusoidal surface waveforms of chirp signals along horizontal cross sections of the material measure. One of the notable features is that the amplitude of each cycle in the chirp signal form is geometrically modulated so that the maximum slope is kept constant. The maximum slope of the chirp-like signal is gradually decreased according to movement in the lateral direction. We fabricated the measurement standard by FIB processing, and it was calibrated by AFM. We tried to evaluate the functional performance of Laser Scanning Microscope by this standard in terms of amplitude response with varying slope angles. As a result, it was concluded that the proposed standard can easily evaluate the performance of surface texture measuring instruments.

  3. Light-responsive smart surface with controllable wettability and excellent stability.

    Science.gov (United States)

    Zhou, Yin-Ning; Li, Jin-Jin; Zhang, Qing; Luo, Zheng-Hong

    2014-10-21

    Novel fluorinated gradient copolymer was designed for smart surface with light-responsive controllable wettability and excellent stability. The switchable mechanism and physicochemical characteristics of the as-prepared surface decorated by designed polymeric material were investigated by ultraviolet-visible (UV-vis) spectrum, scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). Thanks to the functional film and surface roughening, etched silicon surface fabricated by copolymer involving spiropyran (Sp) moieties possesses a fairly large variation range of WCA (28.1°) and achieves the transformation between hydrophilicity (95.2° 109.2°) relative to blank sample (109.2°). The synthetic strategy and developed smart surface offer a promising application in coating with controllable wettability, which bridge the gap between chemical structure and material properties.

  4. Cerebral blood flow response to functional activation

    DEFF Research Database (Denmark)

    Paulson, Olaf B; Hasselbalch, Steen G; Rostrup, Egill

    2010-01-01

    Cerebral blood flow (CBF) and cerebral metabolic rate are normally coupled, that is an increase in metabolic demand will lead to an increase in flow. However, during functional activation, CBF and glucose metabolism remain coupled as they increase in proportion, whereas oxygen metabolism only inc...... the cerebral tissue's increased demand for glucose supply during neural activation with recent evidence supporting a key function for astrocytes in rCBF regulation....

  5. Surface functionalized biocompatible magnetic nanospheres for cancer hyperthermia.

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X.; Novosad, V.; Rozhkova, E. A.; Chen, H.; Yefremenko, V.; Pearson, J.; Torno, M.; Bader, S. D.; Rosengart, A. J.; Univ. Chicago Pritzker School of Medicine

    2007-06-01

    We report a simplified single emulsion (oil-in-water) solvent evaporation protocol to synthesize surface functionalized biocompatible magnetic nanospheres by using highly concentrated hydrophobic magnetite (gel) and a mixture of poly(D,L lactide-co-glycolide) (PLGA) and poly(lactic acid-block-polyethylene glycol-maleimide) (PLA-PEG-maleimide) (10:1 by mass) polymers. The as-synthesized particles are approximately spherical with an average diameter of 360-370 nm with polydispersity index of 0.12-0.18, are surface-functionalized with maleimide groups, and have saturation magnetization values of 25-40 emu/g. The efficiency of the heating induced by 400-kHz oscillating magnetic fields is compared for two samples with different magnetite loadings. Results show that these nanospheres have the potential to provide an efficient cancer-targeted hyperthermia.

  6. Sortase A-mediated functionalization of nanobodies toward surface coupling

    OpenAIRE

    TA, Duy Tien; STEEN REDEKER, Erik; GUEDENS, Wanda; ADRIAENSENS, Peter

    2013-01-01

    The conserved LPETG motif, at which sortase A-catalyzed transpeptidation occurs, is engineered at the C-terminal region of the variable domain of single-domain heavy chain antibody (or nanobody) against Vascular Cell Adhesion Molecule 1 (VCAM1). The recombinant nanobody can then subsequently be ligated, under sortase A catalysis, to a variety of oligoglycine containing targets, including material surfaces, contrast labeling molecules and molecules functionalized for specific chemical coupling...

  7. Functionalization of the hydroxyapatite nanoparticles surface: source of new applications

    International Nuclear Information System (INIS)

    Rojas Sanchez, Leonardo

    2012-01-01

    The surface of the nano-calcium hydroxyapatite, Ca 10 (PO 4 ) 6 (OH) 2 is reacted with stearic acid, succinic anhydride, succinimide and 2 a minoetil dihydrogenphosphate. Introduction of different functional groups is given onto the surface. An ionic interaction is identified by infrared spectroscopy and Raman between the carboxylate groups of the resulting organic molecules and calcium of the hydroxyapatite. The formation of a P-O-P pyrophosphate type bond has been for 2-aminoethyl dihydrogen phosphate with hydroxyapatite groups. Hydroxyapatite phase was remained in all cases after the reaction as demonstrated by diffraction of x-ray in powder. The amount of spiked molecules is quantified by analysis of thermal degradation which together with the determination of the surface area by BET isotherms of nitrogen adsorption. A degree of surface coverage is estimated by the organic molecules. A maximum percentage of 71% is obtained for the functionalization with succinic anhydride, followed by 57% for the reaction with stearic acid. Dilute suspensions of different materials were prepared for which in phosphate buffer solution have presented two populations around 2 and 5 μm in diameter for the modified particles. The ζ-Potential of various materials was determined occurring a variation in the potential of the unmodified hydroxyapatite. The particles with physicochemical properties different of the starting hydroxyapatite were obtained, this has expanded the range of application of the material. (author) [es

  8. Surface modification influencing adsorption of red wine constituents: The role of functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Mierczynska-Vasilev, Agnieszka, E-mail: agnieszka.mierczynska-vasilev@awri.com.au; Smith, Paul A., E-mail: paul.smith@awri.com.au

    2016-11-15

    Highlights: • Chemical surface composition affects behaviour of wine adsorption. • SO{sub 3}H and COOH groups adsorb more of the wine nitrogen-containing compounds. • NH{sub 2} and NR{sub 3} groups encourage carbon-containing compounds adsorption. • Red wine constituents after filtration adsorbed more on NR{sub 3} and CHO surfaces. - Abstract: The adsorption of wine constituents at solid surfaces is important in applications such as filtration and membrane fouling, binding to tanks and fittings and interactions with processing aids such as bentonite. The interaction of wine constituents with surfaces is mediated through adsorbed wine components, where the type of constituents, amount, orientation, and conformation are of consequence for the surface response. This study examines the effect of surface chemical functionalities on the adsorption of red wine constituents. Plasma-polymerized films rich in amine, carboxyl, hydroxyl, formyl and methyl functional groups were generated on solid substrates whereas, glycidyltrimethylammonium chloride was covalently attached to allylamine plasma-polymer modified surface and poly(sodium styrenesulfonate) was electrostatically adsorbed to an amine plasma-polymerized surface. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy. The ability of different substrates to adsorb red wine constituents was evaluated by quartz crystal microbalance and atomic force microscopy. The results showed that substrates modified with −SO{sub 3}H and –COOH groups can adsorb more of the wine nitrogen-containing compounds whereas −NH{sub 2} and −NR{sub 3} groups encourage carbon-containing compounds adsorption. Red wine constituents after filtration were adsorbed in higher extend on −NR{sub 3} and –CHO surfaces. The –OH modified surfaces had the lowest ability to absorb wine components.

  9. Surface modification influencing adsorption of red wine constituents: The role of functional groups

    International Nuclear Information System (INIS)

    Mierczynska-Vasilev, Agnieszka; Smith, Paul A.

    2016-01-01

    Highlights: • Chemical surface composition affects behaviour of wine adsorption. • SO_3H and COOH groups adsorb more of the wine nitrogen-containing compounds. • NH_2 and NR_3 groups encourage carbon-containing compounds adsorption. • Red wine constituents after filtration adsorbed more on NR_3 and CHO surfaces. - Abstract: The adsorption of wine constituents at solid surfaces is important in applications such as filtration and membrane fouling, binding to tanks and fittings and interactions with processing aids such as bentonite. The interaction of wine constituents with surfaces is mediated through adsorbed wine components, where the type of constituents, amount, orientation, and conformation are of consequence for the surface response. This study examines the effect of surface chemical functionalities on the adsorption of red wine constituents. Plasma-polymerized films rich in amine, carboxyl, hydroxyl, formyl and methyl functional groups were generated on solid substrates whereas, glycidyltrimethylammonium chloride was covalently attached to allylamine plasma-polymer modified surface and poly(sodium styrenesulfonate) was electrostatically adsorbed to an amine plasma-polymerized surface. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy. The ability of different substrates to adsorb red wine constituents was evaluated by quartz crystal microbalance and atomic force microscopy. The results showed that substrates modified with −SO_3H and –COOH groups can adsorb more of the wine nitrogen-containing compounds whereas −NH_2 and −NR_3 groups encourage carbon-containing compounds adsorption. Red wine constituents after filtration were adsorbed in higher extend on −NR_3 and –CHO surfaces. The –OH modified surfaces had the lowest ability to absorb wine components.

  10. Photo-induced surface functionalization of carbon surfaces: The role of photoelectron ejection

    International Nuclear Information System (INIS)

    Colavita, Paula E.; Sun Bin; Tse, K.-Y.; Hamers, Robert J.

    2008-01-01

    Carbon-based materials are attractive for a wide range of applications, from biomaterials to fuel cells; however, their effective use often requires controlling the surface chemistry to incorporate recognition moieties or reactive centers. The high stability of carbon also makes it a challenging material to functionalize; recently, the use of ultraviolet light (254 nm) to initiate functionalization of carbon surfaces has emerged as a way to obtain carbon/organic interfaces with tailored properties. The authors have investigated the mechanism of covalent grafting of amorphous carbon surfaces with functional organic molecules using the photochemical reaction of terminal alkenes. Measurements comparing the reactivity of different n-alkenes bearing different terminal groups at the terminus opposite the olefin showed pronounced differences in reactivity. They characterized the rate and final coverage of the resulting organic layers using x-ray photoelectron spectroscopy and infrared reflection-absorption spectroscopy. Ultraviolet photoelectron spectroscopy and photocurrent measurements suggested that the reaction involves photoelectron emission from the carbon surface into the liquid phase. Density functional calculations show a strong correlation between the electron affinity of the alkenes and the observed reactivity. The specific terminal group opposite to the olefin was found to play an important role in the stabilization of excess negative charges on the molecule, thus explaining the strong dependence of reactivity on the particular terminal group. These findings suggest that the reaction involves injection of photoelectrons into the alkene acceptor levels, leading to the formation of radical anions in the liquid phase. Finally, the authors demonstrate that the grafting of marginally reactive alkenes can be enhanced by seeding the surface with a small amount of good electron accepting groups. These results provide fundamental new insights into the role of

  11. Filtering Non-Linear Transfer Functions on Surfaces.

    Science.gov (United States)

    Heitz, Eric; Nowrouzezahrai, Derek; Poulin, Pierre; Neyret, Fabrice

    2014-07-01

    Applying non-linear transfer functions and look-up tables to procedural functions (such as noise), surface attributes, or even surface geometry are common strategies used to enhance visual detail. Their simplicity and ability to mimic a wide range of realistic appearances have led to their adoption in many rendering problems. As with any textured or geometric detail, proper filtering is needed to reduce aliasing when viewed across a range of distances, but accurate and efficient transfer function filtering remains an open problem for several reasons: transfer functions are complex and non-linear, especially when mapped through procedural noise and/or geometry-dependent functions, and the effects of perspective and masking further complicate the filtering over a pixel's footprint. We accurately solve this problem by computing and sampling from specialized filtering distributions on the fly, yielding very fast performance. We investigate the case where the transfer function to filter is a color map applied to (macroscale) surface textures (like noise), as well as color maps applied according to (microscale) geometric details. We introduce a novel representation of a (potentially modulated) color map's distribution over pixel footprints using Gaussian statistics and, in the more complex case of high-resolution color mapped microsurface details, our filtering is view- and light-dependent, and capable of correctly handling masking and occlusion effects. Our approach can be generalized to filter other physical-based rendering quantities. We propose an application to shading with irradiance environment maps over large terrains. Our framework is also compatible with the case of transfer functions used to warp surface geometry, as long as the transformations can be represented with Gaussian statistics, leading to proper view- and light-dependent filtering results. Our results match ground truth and our solution is well suited to real-time applications, requires only a few

  12. Bioactivity evolution of the surface functionalized bioactive glasses.

    Science.gov (United States)

    Magyari, Klára; Baia, Lucian; Vulpoi, Adriana; Simon, Simion; Popescu, Octavian; Simon, Viorica

    2015-02-01

    The formation of a calcium phosphate layer on the surface of the SiO2 -CaO-P2 O5 glasses after immersion in simulated body fluid (SBF) generally demonstrates the bioactivity of these materials. Grafting of the surface by chemical bonding can minimize the structural changes in protein adsorbed on the surface. Therefore, in this study our interest was to evaluate the bioactivity and blood biocompatibility of the SiO2 -CaO-P2 O5 glasses after their surface modification by functionalization with aminopropyl-triethoxysilane and/or by fibrinogen. It is shown that the fibrinogen adsorbed on the glass surfaces induces a growing of the apatite-like layer. It is also evidenced that the protein content from SBF influences the growth of the apatite-like layer. Furthermore, the good blood compatibility of the materials after fibrinogen and bovine serum albumin adsorption is proved from the assessment of the β-sheet-β-turn ratio. © 2014 Wiley Periodicals, Inc.

  13. Damage identification in beams by a response surface based technique

    Directory of Open Access Journals (Sweden)

    Teidj S.

    2014-01-01

    Full Text Available In this work, identification of damage in uniform homogeneous metallic beams was considered through the propagation of non dispersive elastic torsional waves. The proposed damage detection procedure consisted of the following sequence. Giving a localized torque excitation, having the form of a short half-sine pulse, the first step was calculating the transient solution of the resulting torsional wave. This torque could be generated in practice by means of asymmetric laser irradiation of the beam surface. Then, a localized defect assumed to be characterized by an abrupt reduction of beam section area with a given height and extent was placed at a known location of the beam. Next, the response in terms of transverse section rotation rate was obtained for a point situated afterwards the defect, where the sensor was positioned. This last could utilize in practice the concept of laser vibrometry. A parametric study has been conducted after that by using a full factorial design of experiments table and numerical simulations based on a finite difference characteristic scheme. This has enabled the derivation of a response surface model that was shown to represent adequately the response of the system in terms of the following factors: defect extent and severity. The final step was performing the inverse problem solution in order to identify the defect characteristics by using measurement.

  14. Molecular dynamics simulation of potentiometric sensor response: the effect of biomolecules, surface morphology and surface charge.

    Science.gov (United States)

    Lowe, B M; Skylaris, C-K; Green, N G; Shibuta, Y; Sakata, T

    2018-05-10

    The silica-water interface is critical to many modern technologies in chemical engineering and biosensing. One technology used commonly in biosensors, the potentiometric sensor, operates by measuring the changes in electric potential due to changes in the interfacial electric field. Predictive modelling of this response caused by surface binding of biomolecules remains highly challenging. In this work, through the most extensive molecular dynamics simulation of the silica-water interfacial potential and electric field to date, we report a novel prediction and explanation of the effects of nano-morphology on sensor response. Amorphous silica demonstrated a larger potentiometric response than an equivalent crystalline silica model due to increased sodium adsorption, in agreement with experiments showing improved sensor response with nano-texturing. We provide proof-of-concept that molecular dynamics can be used as a complementary tool for potentiometric biosensor response prediction. Effects that are conventionally neglected, such as surface morphology, water polarisation, biomolecule dynamics and finite-size effects, are explicitly modelled.

  15. Plasma functionalized surface of commodity polymers for dopamine detection

    Energy Technology Data Exchange (ETDEWEB)

    Fabregat, Georgina [Departament d’Enginyeria Química, E.T.S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, 08028, Barcelona (Spain); Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C’, C/Pasqual i Vila s/n, Barcelona, E-08028 (Spain); Osorio, Joaquin [Departament d’Enginyeria Química, E.T.S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, 08028, Barcelona (Spain); Castedo, Alejandra [Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C’, C/Pasqual i Vila s/n, Barcelona, E-08028 (Spain); Institut de Tècniques Energètiques, E.T.S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, 08028, Barcelona (Spain); Armelin, Elaine [Departament d’Enginyeria Química, E.T.S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, 08028, Barcelona (Spain); Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C’, C/Pasqual i Vila s/n, Barcelona, E-08028 (Spain); and others

    2017-03-31

    Highlights: • Electrochemically inert polymers become electroactive after plasma functionalization. • Selective dopamine detection has been achieved functionalizing polymers with plasma. • Plasma-functionalized polymers are sensitive dopamine detectors. • XPS analyses reflect the transformation of inert polymers into electrosensors. - Abstract: We have fabricated potentially generalizable sensors based on polymeric-modified electrodes for the electrochemical detection of dopamine. Sensitive and selective sensors have been successfully obtained by applying a cold-plasma treatment during 1–2 min not only to conducting polymers but also to electrochemically inert polymers, such as polyethylene, polypropylene, polyvinylpyrrolidone, polycaprolactone and polystyrene. The effects of the plasma in the electrode surface activation, which is an essential requirement for the dopamine detection when inert polymers are used, have been investigated using X-ray photoelectron spectroscopy. Results indicate that exposure of polymer-modified electrodes to cold-plasma produces the formation of a large variety of reactive species adsorbed on the electrode surface, which catalyse the dopamine oxidation. With this technology, which is based on the application of a very simple physical functionalization, we have defined a paradox-based paradigm for the fabrication of electrochemical sensors by using inert and cheap plastics.

  16. ARES: automated response function code. Users manual. [HPGAM and LSQVM

    Energy Technology Data Exchange (ETDEWEB)

    Maung, T.; Reynolds, G.M.

    1981-06-01

    This ARES user's manual provides detailed instructions for a general understanding of the Automated Response Function Code and gives step by step instructions for using the complete code package on a HP-1000 system. This code is designed to calculate response functions of NaI gamma-ray detectors, with cylindrical or rectangular geometries.

  17. Functionalization of silicon nanowire surfaces with metal-organic frameworks

    KAUST Repository

    Liu, Nian

    2011-12-28

    Metal-organic frameworks (MOFs) and silicon nanowires (SiNWs) have been extensively studied due to their unique properties; MOFs have high porosity and specific surface area with well-defined nanoporous structure, while SiNWs have valuable one-dimensional electronic properties. Integration of the two materials into one composite could synergistically combine the advantages of both materials and lead to new applications. We report the first example of a MOF synthesized on surface-modified SiNWs. The synthesis of polycrystalline MOF-199 (also known as HKUST-1) on SiNWs was performed at room temperature using a step-by-step (SBS) approach, and X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy elemental mapping were used to characterize the material. Matching of the SiNW surface functional groups with the MOF organic linker coordinating groups was found to be critical for the growth. Additionally, the MOF morphology can by tuned by changing the soaking time, synthesis temperature and precursor solution concentration. This SiNW/MOF hybrid structure opens new avenues for rational design of materials with novel functionalities. © 2011 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  18. Longitudinal and transverse quasielastic response functions of light nuclei

    International Nuclear Information System (INIS)

    Carlson, J.; Jourdan, J.; Sick, I.; Schiavilla, R.

    2002-01-01

    The 3 He and 4 He longitudinal and transverse response functions are determined from an analysis of the world data on quasielastic inclusive electron scattering. The corresponding Euclidean response functions are derived and compared to those calculated with Green's function Monte Carlo methods, using realistic interactions and currents. Large contributions associated with two-body currents are found, particularly in the 4 He transverse response, in agreement with data. The contributions of the two-body charge and current operators in the 3 He, 4 He, and 6 Li response functions are also studied via sum-rule techniques. A semiquantitative explanation for the observed systematics in the excess of transverse quasielastic strength, as function of mass number and momentum transfer, is provided. Finally, a number of model studies with simplified interactions, currents, and wave functions are carried out to elucidate the role played, in the full calculation, by tensor interactions and correlations

  19. Adaptive Feeding behavior and functional responses in pelagic copepods

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Saiz, Enrico; Tiselius, Peter

    2018-01-01

    Zooplankton may modify their feeding behavior in response to prey availability and presence of predators with implications to populations of both predators and prey. Optimal foraging theory predicts that such responses result in a type II functional response for passive foragers and a type III re...

  20. Linking microbial diversity and functionality of arctic glacial surface habitats.

    Science.gov (United States)

    Lutz, Stefanie; Anesio, Alexandre M; Edwards, Arwyn; Benning, Liane G

    2017-02-01

    Distinct microbial habitats on glacial surfaces are dominated by snow and ice algae, which are the critical players and the dominant primary colonisers and net producers during the melt season. Here for the first time we have evaluated the role of these algae in association with the full microbial community composition (i.e., algae, bacteria, archaea) in distinct surface habitats and on 12 glaciers and permanent snow fields in Svalbard and Arctic Sweden. We cross-correlated these data with the analyses of specific metabolites such as fatty acids and pigments, and a full suite of potential critical physico-chemical parameters including major and minor nutrients, and trace metals. It has been shown that correlations between single algal species, metabolites, and specific geochemical parameters can be used to unravel mixed metabolic signals in complex communities, further assign them to single species and infer their functionality. The data also clearly show that the production of metabolites in snow and ice algae is driven mainly by nitrogen and less so by phosphorus limitation. This is especially important for the synthesis of secondary carotenoids, which cause a darkening of glacial surfaces leading to a decrease in surface albedo and eventually higher melting rates. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. Effect of nanocoating with rhamnogalacturonan-I on surface properties and osteoblasts response

    DEFF Research Database (Denmark)

    Gurzawska, Katarzyna Aleksandra; Svava, Rikke; Syberg, Susanne

    2012-01-01

    -I) on surface properties and osteoblasts response. Three different RG-Is from apple and lupin pectins were modified and coated on amino-functionalized tissue culture polystyrene plates (aminated TCPS). Surface properties were evaluated by scanning electron microscopy, contact angle measurement, atomic force...... microscopy, and X-ray photoelectron spectroscopy. The effects of nanocoating on proliferation, matrix formation and mineralization, and expression of genes (real-time PCR) related to osteoblast differentiation and activity were tested using human osteoblast-like SaOS-2 cells. It was shown that RG-I coatings...

  2. Orbifold Riemann surfaces: Teichmueller spaces and algebras of geodesic functions

    Energy Technology Data Exchange (ETDEWEB)

    Mazzocco, Marta [Loughborough University, Loughborough (United Kingdom); Chekhov, Leonid O [Institute for Theoretical and Experimental Physics (Russian Federation State Scientific Center), Moscow (Russian Federation)

    2009-12-31

    A fat graph description is given for Teichmueller spaces of Riemann surfaces with holes and with Z{sub 2}- and Z{sub 3}-orbifold points (conical singularities) in the Poincare uniformization. The corresponding mapping class group transformations are presented, geodesic functions are constructed, and the Poisson structure is introduced. The resulting Poisson algebras are then quantized. In the particular cases of surfaces with n Z{sub 2}-orbifold points and with one and two holes, the respective algebras A{sub n} and D{sub n} of geodesic functions (classical and quantum) are obtained. The infinite-dimensional Poisson algebra D{sub n}, which is the semiclassical limit of the twisted q-Yangian algebra Y'{sub q}(o{sub n}) for the orthogonal Lie algebra o{sub n}, is associated with the algebra of geodesic functions on an annulus with n Z{sub 2}-orbifold points, and the braid group action on this algebra is found. From this result the braid group actions are constructed on the finite-dimensional reductions of this algebra: the p-level reduction and the algebra D{sub n}. The central elements for these reductions are found. Also, the algebra D{sub n} is interpreted as the Poisson algebra of monodromy data of a Frobenius manifold in the vicinity of a non-semisimple point. Bibliography: 36 titles.

  3. Swarm formation control utilizing elliptical surfaces and limiting functions.

    Science.gov (United States)

    Barnes, Laura E; Fields, Mary Anne; Valavanis, Kimon P

    2009-12-01

    In this paper, we present a strategy for organizing swarms of unmanned vehicles into a formation by utilizing artificial potential fields that were generated from normal and sigmoid functions. These functions construct the surface on which swarm members travel, controlling the overall swarm geometry and the individual member spacing. Nonlinear limiting functions are defined to provide tighter swarm control by modifying and adjusting a set of control variables that force the swarm to behave according to set constraints, formation, and member spacing. The artificial potential functions and limiting functions are combined to control swarm formation, orientation, and swarm movement as a whole. Parameters are chosen based on desired formation and user-defined constraints. This approach is computationally efficient and scales well to different swarm sizes, to heterogeneous systems, and to both centralized and decentralized swarm models. Simulation results are presented for a swarm of 10 and 40 robots that follow circle, ellipse, and wedge formations. Experimental results are included to demonstrate the applicability of the approach on a swarm of four custom-built unmanned ground vehicles (UGVs).

  4. Functional Elements on SIRPα IgV domain Mediate Cell Surface Binding to CD47

    OpenAIRE

    Liu, Yuan; Tong, Qiao; Zhou, Yubin; Lee, Hsiau-Wei; Yang, Jenny J.; Bühring, Hans-Jörg; Chen, Yi-Tien; Ha, Binh; Chen, Celia X-J.; Zen, Ke

    2006-01-01

    SIRPα and SIRPβ1, the two major isoforms of the signal regulatory protein (SIRP) family, are co-expressed in human leukocytes but mediate distinct extracellular binding interactions and divergent cell signaling responses. Previous studies have demonstrated that binding of SIRPα with CD47, another important cell surface molecule, through the extracellular IgV domain regulates important leukocyte functions including macrophage recognition, leukocyte adhesion and transmigration. Although SIRPβ1 ...

  5. Buckling Response of Thick Functionally Graded Plates

    Directory of Open Access Journals (Sweden)

    BOUAZZA MOKHTAR

    2014-11-01

    Full Text Available In this paper, the buckling of a functionally graded plate is studied by using first order shear deformation theory (FSDT. The material properties of the plate are assumed to be graded continuously in the direction of thickness. The variation of the material properties follows a simple power-law distribution in terms of the volume fractions of constituents. The von Karman strains are used to construct the equilibrium equations of the plates subjected to two types of thermal loading, linear temperature rise and gradient through the thickness are considered. The governing equations are reduced to linear differential equation with boundary conditions yielding a simple solution procedure. In addition, the effects of temperature field, volume fraction distributions, and system geometric parameters are investigated. The results are compared with the results of the no shear deformation theory (classic plate theory, CPT.

  6. Comparison of the bidirectional reflectance distribution function of various surfaces

    International Nuclear Information System (INIS)

    Fernandez, R.; Seasholtz, R.G.; Oberle, L.G.; Kadambi, J.R.

    1989-01-01

    This paper describes the development and use of a system to measure the bidirectional reflectance distribution function (BRDF) of various surfaces. The BRDF measurements are to be used in the analysis and design of optical measurement systems such as laser anemometers. An Ar-ion laser (514 nm) was the light source. Preliminary results are presented for eight samples: two glossy black paints, two flat black paints, black glass, sand-blasted Al, unworked Al, and a white paint. A BaSO4 white reflectance standard was used as the reference sample throughout the tests. 8 refs

  7. Theory of synergistic effects: Hill-type response surfaces as 'null-interaction' models for mixtures.

    Science.gov (United States)

    Schindler, Michael

    2017-08-02

    The classification of effects caused by mixtures of agents as synergistic, antagonistic or additive depends critically on the reference model of 'null interaction'. Two main approaches are currently in use, the Additive Dose (ADM) or concentration addition (CA) and the Multiplicative Survival (MSM) or independent action (IA) models. We compare several response surface models to a newly developed Hill response surface, obtained by solving a logistic partial differential equation (PDE). Assuming that a mixture of chemicals with individual Hill-type dose-response curves can be described by an n-dimensional logistic function, Hill's differential equation for pure agents is replaced by a PDE for mixtures whose solution provides Hill surfaces as 'null-interaction' models and relies neither on Bliss independence or Loewe additivity nor uses Chou's unified general theory. An n-dimensional logistic PDE decribing the Hill-type response of n-component mixtures is solved. Appropriate boundary conditions ensure the correct asymptotic behaviour. Mathematica 11 (Wolfram, Mathematica Version 11.0, 2016) is used for the mathematics and graphics presented in this article. The Hill response surface ansatz can be applied to mixtures of compounds with arbitrary Hill parameters. Restrictions which are required when deriving analytical expressions for response surfaces from other principles, are unnecessary. Many approaches based on Loewe additivity turn out be special cases of the Hill approach whose increased flexibility permits a better description of 'null-effect' responses. Missing sham-compliance of Bliss IA, known as Colby's model in agrochemistry, leads to incompatibility with the Hill surface ansatz. Examples of binary and ternary mixtures illustrate the differences between the approaches. For Hill-slopes close to one and doses below the half-maximum effect doses MSM (Colby, Bliss, Finney, Abbott) predicts synergistic effects where the Hill model indicates 'null

  8. Following the surface response of caffeine cocrystals to controlled humidity storage by atomic force microscopy.

    Science.gov (United States)

    Cassidy, A M C; Gardner, C E; Jones, W

    2009-09-08

    Active pharmaceutical ingredient (API) stability in solid state tablet formulation is frequently a function of the relative humidity (RH) environment in which the drug is stored. Caffeine is one such problematic API. Previously reported caffeine cocrystals, however, were found to offer increased resistance to caffeine hydrate formation. Here we report on the use of atomic force microscopy (AFM) to image the surface of two caffeine cocrystal systems to look for differences between the surface and bulk response of the cocrystal to storage in controlled humidity environments. Bulk responses have previously been assessed by powder X-ray diffraction. With AFM, pinning sites were identified at step edges on caffeine/oxalic acid, with these sites leading to non-uniform step movement on going from ambient to 0% RH. At RH >75%, areas of fresh crystal growth were seen on the cocrystal surface. In the case of caffeine/malonic acid the cocrystals were observed to absorb water anisotropically after storage at 75% RH for 2 days, affecting the surface topography of the cocrystal. These results show that AFM expands on the data gathered by bulk analytical techniques, such as powder X-ray diffraction, by providing localised surface information. This surface information may be important for better predicting API stability in isolation and at a solid state API-excipient interface.

  9. Computational optimization of biodiesel combustion using response surface methodology

    Directory of Open Access Journals (Sweden)

    Ganji Prabhakara Rao

    2017-01-01

    Full Text Available The present work focuses on optimization of biodiesel combustion phenomena through parametric approach using response surface methodology. Physical properties of biodiesel play a vital role for accurate simulations of the fuel spray, atomization, combustion, and emission formation processes. Typically methyl based biodiesel consists of five main types of esters: methyl palmitate, methyl oleate, methyl stearate, methyl linoleate, and methyl linolenate in its composition. Based on the amount of methyl esters present the properties of pongamia bio-diesel and its blends were estimated. CONVERGETM computational fluid dynamics software was used to simulate the fuel spray, turbulence and combustion phenomena. The simulation responses such as indicated specific fuel consumption, NOx, and soot were analyzed using design of experiments. Regression equations were developed for each of these responses. The optimum parameters were found out to be compression ratio – 16.75, start of injection – 21.9° before top dead center, and exhaust gas re-circulation – 10.94%. Results have been compared with baseline case.

  10. Do Aging and Tactile Noise Stimulation Affect Responses to Support Surface Translations in Healthy Adults?

    Directory of Open Access Journals (Sweden)

    Marius Dettmer

    2016-01-01

    Full Text Available Appropriate neuromuscular responses to support surface perturbations are crucial to prevent falls, but aging-related anatomical and physiological changes affect the appropriateness and efficiency of such responses. Low-level noise application to sensory receptors has shown to be effective for postural improvement in a variety of different balance tasks, but it is unknown whether this intervention may have value for improvement of corrective postural responses. Ten healthy younger and ten healthy older adults were exposed to sudden backward translations of the support surface. Low-level noise (mechanical vibration to the foot soles was added during random trials and temporal (response latency and spatial characteristics (maximum center-of-pressure excursion and anterior-posterior path length of postural responses were assessed. Mixed-model ANOVA was applied for analysis of postural response differences based on age and vibration condition. Age affected postural response characteristics, but older adults were well able to maintain balance when exposed to a postural perturbation. Low-level noise application did not affect any postural outcomes. Healthy aging affects some specific measures of postural stability, and in high-functioning older individuals, a low-level noise intervention may not be valuable. More research is needed to investigate if recurring fallers and neuropathy patients could benefit from the intervention in postural perturbation tasks.

  11. Density Functional Theory and Atomic Force Microscopy Study of Oleate Functioned on Siderite Surface

    Directory of Open Access Journals (Sweden)

    Lixia Li

    2018-01-01

    Full Text Available Efficiently discovering the interaction of the collector oleate and siderite is of great significance for understanding the inherent function of siderite weakening hematite reverse flotation. For this purpose, investigation of the adsorption behavior of oleate on siderite surface was performed by density functional theory (DFT calculations associating with atomic force microscopy (AFM imaging. The siderite crystal geometry was computationally optimized via convergence tests. Calculated results of the interaction energy and the Mulliken population verified that the collector oleate adsorbed on siderite surface and the covalent bond was established as a result of electrons transferring from O1 atoms (in oleate molecule to Fe1 atoms (in siderite lattice. Therefore, valence-electrons’ configurations of Fe1 and O1 changed into 3d6.514s0.37 and 2s1.832p4.73 from 3d6.214s0.31 and 2s1.83p4.88 correspondingly. Siderite surfaces with or without oleate functioned were examined with the aid of AFM imaging in PeakForce Tapping mode, and the functioned siderite surface was found to be covered by vesicular membrane matters with the average roughness of 16.4 nm assuring the oleate adsorption. These results contributed to comprehending the interaction of oleate and siderite.

  12. Bovine serum albumin adsorption on functionalized porous silicon surfaces

    Science.gov (United States)

    Tay, Li-Lin; Rowell, Nelson L.; Lockwood, David J.; Boukherroub, Rabah

    2004-10-01

    The large surface area within porous Si (pSi) and its strong room temperature photoluminescence (PL) make it an ideal host for biological sensors. In particular, the development of pSi-based optical sensors for DNA, enzyme and other biochemical molecules have become of great interest. Here, we demonstrate that the in-situ monitoring of the pSi PL behaviour can be used as a positive identification of bovine serum albumin (BSA) protein adsorption inside the porous matrix. Electrochemically prepared pSi films were first functionalized with undecylenic acid to produce an organic monolayer covalently attached to the porous silicon surfaces. The acid terminal group also provided favourable BSA binding sites on the pSi matrix sidewalls. In-situ PL spectra showed a gradual red shift (up to 12 meV) in the PL peak energy due to the protein incorporation into the porous matrix. The PL then exhibited a continuous blue shift after saturation of the protein molecules in the pores. This blue shift of the PL peak frequency and a steady increase in the PL intensity is evidence of surface oxidation. Comparing the specular reflectance obtained by Fourier transform infrared spectroscopy (FTIR) before and after BSA incubation confirmed the adsorption of protein in the pSi matrix.

  13. Modelling and analysis of tool wear and surface roughness in hard turning of AISI D2 steel using response surface methodology

    Directory of Open Access Journals (Sweden)

    M. Junaid Mir

    2018-01-01

    Full Text Available The present work deals with some machinability studies on tool wear and surface roughness, in finish hard turning of AISI D2 steel using PCBN, Mixed ceramic and coated carbide inserts. The machining experiments are conducted based on the response surface methodology (RSM. Combined effects of three cutting parameters viz., cutting speed, cutting time and tool hardness on the two performance outputs (i.e. VB and Ra, are explored employing the analysis of variance (ANOVA.The relationship(s between input variables and the response parameters are determined using a quadratic regression model. The results show that the tool wear was influenced principally by the cutting time and in the second level by the cutting tool hardness. On the other hand, cutting time was the dominant factor affecting workpiece surface roughness followed by cutting speed. Finally, the multiple response optimizations of tool wear and surface roughness were carried out using the desirability function approach (DFA.

  14. Postural Stability Margins as a Function of Support Surface Slopes.

    Directory of Open Access Journals (Sweden)

    Aviroop Dutt-Mazumder

    Full Text Available This investigation examined the effects of slope of the surface of support (35°, 30°, 20°, 10° Facing(Toe Down, 0° Flat and 10°, 20°, 25° Facing (Toe Up and postural orientation on the margins of postural stability in quiet standing of young adults. The findings showed that the center of pressure-CoP (displacement, area and length had least motion at the baseline (0° Flat platform condition that progressively increased as a function of platform angle in both facing up and down directions. The virtual time to collision (VTC dynamics revealed that the spatio-temporal margins to the functional stability boundary were progressively smaller and the VTC time series also more regular (SampEn-Sample Entropy as slope angle increased. Surface slope induces a restricted stability region with lower dimension VTC dynamics that is more constrained when postural orientation is facing down the slope. These findings provide further evidence that VTC acts as a control variable in standing posture that is influenced by the emergent dynamics of the individual-environment-task interaction.

  15. Postural Stability Margins as a Function of Support Surface Slopes.

    Science.gov (United States)

    Dutt-Mazumder, Aviroop; Slobounov, Seymon M; Challis, John Henry; Newell, Karl Maxim

    2016-01-01

    This investigation examined the effects of slope of the surface of support (35°, 30°, 20°, 10° Facing(Toe) Down, 0° Flat and 10°, 20°, 25° Facing (Toe) Up) and postural orientation on the margins of postural stability in quiet standing of young adults. The findings showed that the center of pressure-CoP (displacement, area and length) had least motion at the baseline (0° Flat) platform condition that progressively increased as a function of platform angle in both facing up and down directions. The virtual time to collision (VTC) dynamics revealed that the spatio-temporal margins to the functional stability boundary were progressively smaller and the VTC time series also more regular (SampEn-Sample Entropy) as slope angle increased. Surface slope induces a restricted stability region with lower dimension VTC dynamics that is more constrained when postural orientation is facing down the slope. These findings provide further evidence that VTC acts as a control variable in standing posture that is influenced by the emergent dynamics of the individual-environment-task interaction.

  16. Functional Roles of Syk in Macrophage-Mediated Inflammatory Responses

    Science.gov (United States)

    Yi, Young-Su; Son, Young-Jin; Ryou, Chongsuk; Sung, Gi-Ho; Kim, Jong-Hoon; Cho, Jae Youl

    2014-01-01

    Inflammation is a series of complex biological responses to protect the host from pathogen invasion. Chronic inflammation is considered a major cause of diseases, such as various types of inflammatory/autoimmune diseases and cancers. Spleen tyrosine kinase (Syk) was initially found to be highly expressed in hematopoietic cells and has been known to play crucial roles in adaptive immune responses. However, recent studies have reported that Syk is also involved in other biological functions, especially in innate immune responses. Although Syk has been extensively studied in adaptive immune responses, numerous studies have recently presented evidence that Syk has critical functions in macrophage-mediated inflammatory responses and is closely related to innate immune response. This review describes the characteristics of Syk-mediated signaling pathways, summarizes the recent findings supporting the crucial roles of Syk in macrophage-mediated inflammatory responses and diseases, and discusses Syk-targeted drug development for the therapy of inflammatory diseases. PMID:25045209

  17. Functional Roles of Syk in Macrophage-Mediated Inflammatory Responses

    Directory of Open Access Journals (Sweden)

    Young-Su Yi

    2014-01-01

    Full Text Available Inflammation is a series of complex biological responses to protect the host from pathogen invasion. Chronic inflammation is considered a major cause of diseases, such as various types of inflammatory/autoimmune diseases and cancers. Spleen tyrosine kinase (Syk was initially found to be highly expressed in hematopoietic cells and has been known to play crucial roles in adaptive immune responses. However, recent studies have reported that Syk is also involved in other biological functions, especially in innate immune responses. Although Syk has been extensively studied in adaptive immune responses, numerous studies have recently presented evidence that Syk has critical functions in macrophage-mediated inflammatory responses and is closely related to innate immune response. This review describes the characteristics of Syk-mediated signaling pathways, summarizes the recent findings supporting the crucial roles of Syk in macrophage-mediated inflammatory responses and diseases, and discusses Syk-targeted drug development for the therapy of inflammatory diseases.

  18. Response of Moist Convection to Multi-scale Surface Flux Heterogeneity

    Science.gov (United States)

    Kang, S. L.; Ryu, J. H.

    2015-12-01

    We investigate response of moist convection to multi-scale feature of the spatial variation of surface sensible heat fluxes (SHF) in the afternoon evolution of the convective boundary layer (CBL), utilizing a mesoscale-domain large eddy simulation (LES) model. The multi-scale surface heterogeneity feature is analytically created as a function of the spectral slope in the wavelength range from a few tens of km to a few hundreds of m in the spectrum of surface SHF on a log-log scale. The response of moist convection to the κ-3 - slope (where κ is wavenumber) surface SHF field is compared with that to the κ-2 - slope surface, which has a relatively weak mesoscale feature, and the homogeneous κ0 - slope surface. Given the surface energy balance with a spatially uniform available energy, the prescribed SHF has a 180° phase lag with the latent heat flux (LHF) in a horizontal domain of (several tens of km)2. Thus, warmer (cooler) surface is relatively dry (moist). For all the cases, the same observation-based sounding is prescribed for the initial condition. For all the κ-3 - slope surface heterogeneity cases, early non-precipitating shallow clouds further develop into precipitating deep thunderstorms. But for all the κ-2 - slope cases, only shallow clouds develop. We compare the vertical profiles of domain-averaged fluxes and variances, and the contribution of the mesoscale and turbulence contributions to the fluxes and variances, between the κ-3 versus κ-2 slope cases. Also the cross-scale processes are investigated.

  19. Near surface mechanical properties of optical single crystals and surface response to deterministic microgrinding

    Science.gov (United States)

    Randi, Joseph A., III

    2005-12-01

    This thesis makes use of microindentation, nanoindentation and nanoscratching methods to better understand the mechanical properties of single crystalline silicon, calcium fluoride, and magnesium fluoride. These properties are measured and are used to predict the material's response to material removal, specifically by grinding and polishing, which is a combination of elastic, plastic and fracture processes. The hardness anisotropy during Knoop microindentation, hardness from nanoindentation, and scratch morphology from nanoscratching are reported. This information is related to the surface microroughness from grinding. We show that mechanical property relationships that predict the surface roughness from lapping and deterministic microgrinding of optical glasses are applicable to single crystals. We show the range of hardness from some of the more common crystallographic faces. Magnesium fluoride, having a tetragonal structure, has 2-fold hardness anisotropy. Nanoindentation, as expected provides higher hardness than microindentation, but anisotropy is not observed. Nanoscratching provides the scratch profile during loading, after the load has been removed, and the coefficient of friction during the loading. Ductile and brittle mode scratching is present with brittle mode cracking being orientation specific. Subsurface damage (SSD) measurements are made using a novel process known as the MRF technique. Magnetorheological finishing is used to polish spots into the ground surface where SSD can be viewed. SSD is measured using an optical microscope and knowledge of the spot profile. This technique is calibrated with a previous technique and implemented to accurately measure SSD in single crystals. The data collected are compared to the surface microroughness of the ground surface, resulting in an upper bound relationship. The results indicate that SSD is always less than 1.4 times the peak-to-valley surface microroughness for single crystals regardless of the

  20. Surface Functionalization of Orthopedic Titanium Implants with Bone Sialoprotein.

    Directory of Open Access Journals (Sweden)

    Andreas Baranowski

    Full Text Available Orthopedic implant failure due to aseptic loosening and mechanical instability remains a major problem in total joint replacement. Improving osseointegration at the bone-implant interface may reduce micromotion and loosening. Bone sialoprotein (BSP has been shown to enhance bone formation when coated onto titanium femoral implants and in rat calvarial defect models. However, the most appropriate method of BSP coating, the necessary level of BSP coating, and the effect of BSP coating on cell behavior remain largely unknown. In this study, BSP was covalently coupled to titanium surfaces via an aminosilane linker (APTES, and its properties were compared to BSP applied to titanium via physisorption and untreated titanium. Cell functions were examined using primary human osteoblasts (hOBs and L929 mouse fibroblasts. Gene expression of specific bone turnover markers at the RNA level was detected at different intervals. Cell adhesion to titanium surfaces treated with BSP via physisorption was not significantly different from that of untreated titanium at any time point, whereas BSP application via covalent coupling caused reduced cell adhesion during the first few hours in culture. Cell migration was increased on titanium disks that were treated with higher concentrations of BSP solution, independent of the coating method. During the early phases of hOB proliferation, a suppressive effect of BSP was observed independent of its concentration, particularly when BSP was applied to the titanium surface via physisorption. Although alkaline phosphatase activity was reduced in the BSP-coated titanium groups after 4 days in culture, increased calcium deposition was observed after 21 days. In particular, the gene expression level of RUNX2 was upregulated by BSP. The increase in calcium deposition and the stimulation of cell differentiation induced by BSP highlight its potential as a surface modifier that could enhance the osseointegration of orthopedic implants

  1. Maximization of fructose esters synthesis by response surface methodology.

    Science.gov (United States)

    Neta, Nair Sampaio; Peres, António M; Teixeira, José A; Rodrigues, Ligia R

    2011-07-01

    Enzymatic synthesis of fructose fatty acid ester was performed in organic solvent media, using a purified lipase from Candida antartica B immobilized in acrylic resin. Response surface methodology with a central composite rotatable design based on five levels was implemented to optimize three experimental operating conditions (temperature, agitation and reaction time). A statistical significant cubic model was established. Temperature and reaction time were found to be the most significant parameters. The optimum operational conditions for maximizing the synthesis of fructose esters were 57.1°C, 100 rpm and 37.8 h. The model was validated in the identified optimal conditions to check its adequacy and accuracy, and an experimental esterification percentage of 88.4% (±0.3%) was obtained. These results showed that an improvement of the enzymatic synthesis of fructose esters was obtained under the optimized conditions. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Multiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, Peter [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Gillespie, Andrew [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Stalla, David [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Dohnke, Elmar [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics

    2017-02-20

    The purpose of the project “Multiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage” is the development of materials that store hydrogen (H2) by adsorption in quantities and at conditions that outperform current compressed-gas H2 storage systems for electric power generation from hydrogen fuel cells (HFCs). Prominent areas of interest for HFCs are light-duty vehicles (“hydrogen cars”) and replacement of batteries with HFC systems in a wide spectrum of applications, ranging from forklifts to unmanned areal vehicles to portable power sources. State-of-the-art compressed H2 tanks operate at pressures between 350 and 700 bar at ambient temperature and store 3-4 percent of H2 by weight (wt%) and less than 25 grams of H2 per liter (g/L) of tank volume. Thus, the purpose of the project is to engineer adsorbents that achieve storage capacities better than compressed H2 at pressures less than 350 bar. Adsorption holds H2 molecules as a high-density film on the surface of a solid at low pressure, by virtue of attractive surface-gas interactions. At a given pressure, the density of the adsorbed film is the higher the stronger the binding of the molecules to the surface is (high binding energies). Thus, critical for high storage capacities are high surface areas, high binding energies, and low void fractions (high void fractions, such as in interstitial space between adsorbent particles, “waste” storage volume by holding hydrogen as non-adsorbed gas). Coexistence of high surface area and low void fraction makes the ideal adsorbent a nanoporous monolith, with pores wide enough to hold high-density hydrogen films, narrow enough to minimize storage as non-adsorbed gas, and thin walls between pores to minimize the volume occupied by solid instead of hydrogen. A monolith can be machined to fit into a rectangular tank (low pressure, conformable tank), cylindrical tank

  3. Understanding the biological responses of nanostructured metals and surfaces

    Science.gov (United States)

    Lowe, Terry C.; Reiss, Rebecca A.

    2014-08-01

    Metals produced by Severe Plastic Deformation (SPD) offer distinct advantages for medical applications such as orthopedic devices, in part because of their nanostructured surfaces. We examine the current theoretical foundations and state of knowledge for nanostructured biomaterials surface optimization within the contexts that apply to bulk nanostructured metals, differentiating how their microstructures impact osteogenesis, in particular, for Ultrafine Grained (UFG) titanium. Then we identify key gaps in the research to date, pointing out areas which merit additional focus within the scientific community. For example, we highlight the potential of next-generation DNA sequencing techniques (NGS) to reveal gene and non-coding RNA (ncRNA) expression changes induced by nanostructured metals. While our understanding of bio-nano interactions is in its infancy, nanostructured metals are already being marketed or developed for medical devices such as dental implants, spinal devices, and coronary stents. Our ability to characterize and optimize the biological response of cells to SPD metals will have synergistic effects on advances in materials, biological, and medical science.

  4. Understanding the biological responses of nanostructured metals and surfaces

    International Nuclear Information System (INIS)

    Lowe, Terry C; A Reiss, Rebecca

    2014-01-01

    Metals produced by Severe Plastic Deformation (SPD) offer distinct advantages for medical applications such as orthopedic devices, in part because of their nanostructured surfaces. We examine the current theoretical foundations and state of knowledge for nanostructured biomaterials surface optimization within the contexts that apply to bulk nanostructured metals, differentiating how their microstructures impact osteogenesis, in particular, for Ultrafine Grained (UFG) titanium. Then we identify key gaps in the research to date, pointing out areas which merit additional focus within the scientific community. For example, we highlight the potential of next-generation DNA sequencing techniques (NGS) to reveal gene and non-coding RNA (ncRNA) expression changes induced by nanostructured metals. While our understanding of bio-nano interactions is in its infancy, nanostructured metals are already being marketed or developed for medical devices such as dental implants, spinal devices, and coronary stents. Our ability to characterize and optimize the biological response of cells to SPD metals will have synergistic effects on advances in materials, biological, and medical science

  5. Response functions of free mass gravitational wave antennas

    Science.gov (United States)

    Estabrook, F. B.

    1985-01-01

    The work of Gursel, Linsay, Spero, Saulson, Whitcomb and Weiss (1984) on the response of a free-mass interferometric antenna is extended. Starting from first principles, the earlier work derived the response of a 2-arm gravitational wave antenna to plane polarized gravitational waves. Equivalent formulas (generalized slightly to allow for arbitrary elliptical polarization) are obtained by a simple differencing of the '3-pulse' Doppler response functions of two 1-arm antennas. A '4-pulse' response function is found, with quite complicated angular dependences for arbitrary incident polarization. The differencing method can as readily be used to write exact response functions ('3n+1 pulse') for antennas having multiple passes or more arms.

  6. Optimum Design of a Helicopter Rotor for Low Vibration Using Aeroelastic Analysis and Response Surface Methods

    Science.gov (United States)

    Ganguli, R.

    2002-11-01

    An aeroelastic analysis based on finite elements in space and time is used to model the helicopter rotor in forward flight. The rotor blade is represented as an elastic cantilever beam undergoing flap and lag bending, elastic torsion and axial deformations. The objective of the improved design is to reduce vibratory loads at the rotor hub that are the main source of helicopter vibration. Constraints are imposed on aeroelastic stability, and move limits are imposed on the blade elastic stiffness design variables. Using the aeroelastic analysis, response surface approximations are constructed for the objective function (vibratory hub loads). It is found that second order polynomial response surfaces constructed using the central composite design of the theory of design of experiments adequately represents the aeroelastic model in the vicinity of the baseline design. Optimization results show a reduction in the objective function of about 30 per cent. A key accomplishment of this paper is the decoupling of the analysis problem and the optimization problems using response surface methods, which should encourage the use of optimization methods by the helicopter industry.

  7. Evaluation of the detector response function digital conventional radiology

    International Nuclear Information System (INIS)

    Arino Gil, A.; Hernandez Rodriguez, J.; Mateos Salvador, P.; Rodriguez Lopez, B.; Font Gelabert, J. C.

    2013-01-01

    The objective of this work is to obtain the response function that relates the air kerma at the entrance of the detector and pixel value, for a series of digital detectors of conventional Radiology model Optimus DigitalDiagnost Philips () and 6000 Definium General Electric. From the set of measurements is obtained a response function for each reference type of detector, and compared with those published in the literature for these teams. (Author)

  8. A photometric function of planetary surfaces for gourmets

    Science.gov (United States)

    Shkuratov, Yuriy; Korokhin, Viktor; Shevchenko, Vasilij; Mikhalchenko, Olga; Belskaya, Irina; Kaydash, Vadym; Videen, Gorden; Zubko, Evgenij; Velikodsky, Yuriy

    2018-03-01

    A new photometric model with small number of parameters is presented. The model is based on an assumption that there exist such surfaces for which spatial brightness variations caused by small topography undulations can be reproduced exactly by corresponding spatial variations of albedo. This indistinguishability results in a differential equation suggesting a new photometric function that generalizes, in particular, the Akimov disk-function. Our model provides excellent fits in a wide phase-angle range for integral observations of asteroids of different albedos. We also carried out fitting to integral observations of the Moon and Mercury, confirming difficulties in describing Mercury's phase function at large phase angles, which were also found for the Hapke model. Comparisons of global latitude and longitude trends with our model calculations have shown good coincidence for the Moon. To retrieve the lunar trends, we use the phase-ratio technique, applying it to our telescope observations. Mapping the model parameters using LROC WAC data were carried out for a region comprising the Reiner Gamma formation. This mapping allows us to calculate phase-ratio images of the region, showing at large phase angles systematically steeper phase curves of young craters and smaller steepness for the very Reiner Gamma formation.

  9. Functionalized Surface Geometries Induce: “Bone: Formation by Autoinduction”

    Directory of Open Access Journals (Sweden)

    Ugo Ripamonti

    2018-02-01

    Full Text Available The induction of tissue formation, and the allied disciplines of tissue engineering and regenerative medicine, have flooded the twenty-first century tissue biology scenario and morphed into high expectations of a fulfilling regenerative dream of molecularly generated tissues and organs in assembling human tissue factories. The grand conceptualization of deploying soluble molecular signals, first defined by Turing as forms generating substances, or morphogens, stemmed from classic last century studies that hypothesized the presence of morphogens in several mineralized and non-mineralized mammalian matrices. The realization of morphogens within mammalian matrices devised dissociative extractions and chromatographic procedures to isolate, purify, and finally reconstitute the cloned morphogens, found to be members of the transforming growth factor-β (TGF-β supergene family, with insoluble signals or substrata to induce de novo tissue induction and morphogenesis. Can we however construct macroporous bioreactors per se capable of inducing bone formation even without the exogenous applications of the osteogenic soluble molecular signals of the TGF-β supergene family? This review describes original research on coral-derived calcium phosphate-based macroporous constructs showing that the formation of bone is independent of the exogenous application of the osteogenic soluble signals of the TGF-β supergene family. Such signals are the molecular bases of the induction of bone formation. The aim of this review is to primarily describe today's hottest topic of biomaterials' science, i.e., to construct and define osteogenetic biomaterials' surfaces that per se, in its own right, do initiate the induction of bone formation. Biomaterials are often used to reconstruct osseous defects particularly in the craniofacial skeleton. Edentulism did spring titanium implants as tooth replacement strategies. No were else that titanium surfaces require functionalized

  10. Optimization of sustained release aceclofenac microspheres using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Deshmukh, Rameshwar K.; Naik, Jitendra B., E-mail: jitunaik@gmail.com

    2015-03-01

    Polymeric microspheres containing aceclofenac were prepared by single emulsion (oil-in-water) solvent evaporation method using response surface methodology (RSM). Microspheres were prepared by changing formulation variables such as the amount of Eudragit® RS100 and the amount of polyvinyl alcohol (PVA) by statistical experimental design in order to enhance the encapsulation efficiency (E.E.) of the microspheres. The resultant microspheres were evaluated for their size, morphology, E.E., and in vitro drug release. The amount of Eudragit® RS100 and the amount of PVA were found to be significant factors respectively for determining the E.E. of the microspheres. A linear mathematical model equation fitted to the data was used to predict the E.E. in the optimal region. Optimized formulation of microspheres was prepared using optimal process variables setting in order to evaluate the optimization capability of the models generated according to IV-optimal design. The microspheres showed high E.E. (74.14 ± 0.015% to 85.34 ± 0.011%) and suitably sustained drug release (minimum; 40% to 60%; maximum) over a period of 12 h. The optimized microspheres formulation showed E.E. of 84.87 ± 0.005 with small error value (1.39). The low magnitudes of error and the significant value of R{sup 2} in the present investigation prove the high prognostic ability of the design. The absence of interactions between drug and polymers was confirmed by Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRPD) revealed the dispersion of drug within microspheres formulation. The microspheres were found to be discrete, spherical with smooth surface. The results demonstrate that these microspheres could be promising delivery system to sustain the drug release and improve the E.E. thus prolong drug action and achieve the highest healing effect with minimal gastrointestinal side effects. - Highlights: • Aceclofenac microspheres

  11. Water response to ganglioside GM1 surface remodelling.

    Science.gov (United States)

    Brocca, P; Rondelli, V; Mallamace, F; Di Bari, M T; Deriu, A; Lohstroh, W; Del Favero, E; Corti, M; Cantu', L

    2017-01-01

    Gangliosides are biological glycolipids participating in rafts, structural and functional domains of cell membranes. Their headgroups are able to assume different conformations when packed on the surface of an aggregate, more lying or standing. Switching between different conformations is possible, and is a collective event. Switching can be induced, in model systems, by concentration or temperature increase, then possibly involving ganglioside-water interaction. In the present paper, the effect of GM1 ganglioside headgroup conformation on the water structuring and interactions is addressed. Depolarized Rayleigh Scattering, Raman Scattering, Quasielastic Neutron Scattering and NMR measurements were performed on GM1 ganglioside solutions, focusing on solvent properties. All used techniques agree in evidencing differences in the structure and dynamics of solvent water on different time-and-length scales in the presence of either GM1 headgroup conformations. In general, all results indicate that both the structural properties of solvent water and its interactions with the sugar headgroups of GM1 respond to surface remodelling. The extent of this modification is much higher than expected and, interestingly, ganglioside headgroups seem to turn from cosmotropes to chaotropes upon collective rearrangement from the standing- to the lying-conformation. In a biological perspective, water structure modulation could be one of the physico-chemical elements contributing to the raft strategy, both for rafts formation and persistence and for their functional aspects. In particular, the interaction with approaching bodies could be favoured or inhibited or triggered by complex-sugar-sequence conformational switch. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Response surface reconciliation method of bolted joints structure

    Directory of Open Access Journals (Sweden)

    Yunus Mohd Azmi

    2017-01-01

    Full Text Available Structural joining methods such as bolted joints are commonly used for the assembly of structural components due to their simplicity and easy maintenance. Understandably, the dynamic characteristic of bolted joined structure is mainly influenced by the properties of their joints such as preload on the bolts and joints stiffness which alter the measured dynamics response of the structure. Therefore, the need to include the local effect of the bolted joints into the numerical model of the bolted joined structure is vitally important in order to represent the model accurately. In this paper, a few types of connector elements that can be used to represent the bolted joints such as CBAR, CBEAM and CELAS have been investigated numerically and experimentally. The initial numerical results of these element connectors are compared with the experimental results in term of natural frequencies and mode shapes. The comparative evaluation of numerical and the experimental data are performed in order to provide some insights of inaccuracies in the numerical model due to invalid assumption in the numerical modelling such as geometry, material properties, and boundary conditions. The discrepancies between both results (numerical and experimental data are then corrected using the response surface reconciliation method (RSRM through which the finite element model is altered in order to provide closer agreement with the measured data so that it can be used for subsequence analysis.

  13. Highly sensitive BTX detection using surface functionalized QCM sensor

    Energy Technology Data Exchange (ETDEWEB)

    Bozkurt, Asuman Aşıkoğlu; Özdemir, Okan; Altındal, Ahmet, E-mail: altindal@yildiz.edu.tr [Department of Physics, Yildiz Technical University, Davutpasa, 34210 Istanbul (Turkey)

    2016-03-25

    A novel organic compound was designed and successfully synthesized for the fabrication of QCM based sensors to detect the low concentrations of BTX gases in indoor air. The effect of the long-range electron orbital delocalization on the BTX vapour sensing properties of azo-bridged Pcs based chemiresistor-type sensors have also been investigated in this work. The sensing behaviour of the film for the online detection of volatile organic solvent vapors was investigated by utilizing an AT-cut quartz crystal resonator. It was observed that the adsorption of the target molecules on the coating surface cause a reversible negative frequency shift of the resonator. Thus, a variety of solvent vapors can be detected by using the phthalocyanine film as sensitive coating, with sensitivity in the ppm range and response times in the order of several seconds depending on the molecular structure of the organic solvent.

  14. The response of electrostatic probes via the λ-function

    DEFF Research Database (Denmark)

    Rerup, T.O.; Crichton, George C; McAllister, Iain Wilson

    1994-01-01

    The response of an electrostatic probe is examined with reference to a planar spacer. The study involves the numerical calculation of the probe λ-function, from which response-related characteristic parameters can be derived. These parameters enable the probe detection sensitivity and spatial...

  15. Zinc surface complexes on birnessite: A density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Kideok D.; Refson, Keith; Sposito, Garrison

    2009-01-05

    Biogeochemical cycling of zinc is strongly influenced by sorption on birnessite minerals (layer-type MnO2), which are found in diverse terrestrial and aquatic environments. Zinc has been observed to form both tetrahedral (Zn{sup IV}) and octahedral (Zn{sup VI}) triple-corner-sharing surface complexes (TCS) at Mn(IV) vacancy sites in hexagonal birnessite. The octahedral complex is expected to be similar to that of Zn in the Mn oxide mineral, chalcophanite (ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O), but the reason for the occurrence of the four-coordinate Zn surface species remains unclear. We address this issue computationally using spin-polarized Density Functional Theory (DFT) to examine the Zn{sub IV}-TCS and Zn{sup VI}-TCS species. Structural parameters obtained by DFT geometry optimization were in excellent agreement with available experimental data on Zn-birnessites. Total energy, magnetic moments, and electron-overlap populations obtained by DFT for isolated Zn{sup IV}-TCS revealed that this species is stable in birnessite without a need for Mn(III) substitution in the octahedral sheet and that it is more effective in reducing undersaturation of surface O at a Mn vacancy than is Zn{sub VI}-TCS. Comparison between geometry-optimized ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O (chalcophanite) and the hypothetical monohydrate mineral, ZnMn{sub 3}O{sub 7} {center_dot} H{sub 2}O, which contains only tetrahedral Zn, showed that the hydration state of Zn significantly affects birnessite structural stability. Finally, our study also revealed that, relative to their positions in an ideal vacancy-free MnO{sub 2}, Mn nearest to Zn in a TCS surface complex move toward the vacancy by 0.08-0.11 {angstrom}, while surface O bordering the vacancy move away from it by 0.16-0.21 {angstrom}, in agreement with recent X-ray absorption spectroscopic analyses.

  16. Salinity-Dependent Adhesion Response Properties of Aluminosilicate (K-Feldspar) Surfaces

    DEFF Research Database (Denmark)

    Lorenz, Bärbel; Ceccato, Marcel; Andersson, Martin Peter

    2017-01-01

    is composed predominantly of quartz with some clay, but feldspar grains are often also present. While the wettability of quartz and clay surfaces has been thoroughly investigated, little is known about the adhesion properties of feldspar. We explored the interaction of model oil compounds, molecules...... in well sorted sandstone. Adhesion forces, measured with the chemical force mapping (CFM) mode of atomic force microscopy (AFM), showed a low salinity effect on the fresh feldspar surfaces. Adhesion force, measured with -COO(H)-functionalized tips, was 60% lower in artificial low salinity seawater (LS......, ∼1500 ppm total dissolved solids) than in the high salinity solution, artificial seawater (HS, ASW, ∼35 600 ppm). Adhesion with the -CH3 tips was as much as 30% lower in LS than in HS. Density functional theory calculations indicated that the low salinity response resulted from expansion of the electric...

  17. 32 CFR 352a.4 - Responsibilities and functions.

    Science.gov (United States)

    2010-07-01

    ...) ORGANIZATIONAL CHARTERS DEFENSE FINANCE AND ACCOUNTING SERVICE (DFAS) § 352a.4 Responsibilities and functions. (a) The Director, Defense Finance and Accounting Service (DFAS), is the principal DoD executive for finance and accounting requirements, systems, and functions identified in DoD Directive 5118.3, 1 and...

  18. Dynamic response function and large-amplitude dissipative collective motion

    International Nuclear Information System (INIS)

    Wu Xizhen; Zhuo Yizhong; Li Zhuxia; Sakata, Fumihiko.

    1993-05-01

    Aiming at exploring microscopic dynamics responsible for the dissipative large-amplitude collective motion, the dynamic response and correlation functions are introduced within the general theory of nuclear coupled-master equations. The theory is based on the microscopic theory of nuclear collective dynamics which has been developed within the time-dependent Hartree-Fock (TDHF) theory for disclosing complex structure of the TDHF-manifold. A systematic numerical method for calculating the dynamic response and correlation functions is proposed. By performing numerical calculation for a simple model Hamiltonian, it is pointed out that the dynamic response function gives an important information in understanding the large-amplitude dissipative collective motion which is described by an ensemble of trajectories within the TDHF-manifold. (author)

  19. Proteomic Response of Pseudomonas aeruginosa PAO1 Adhering to Solid Surfaces

    Directory of Open Access Journals (Sweden)

    Morgan Guilbaud

    2017-08-01

    Full Text Available Pseudomonas aeruginosa is a pathogenic micro-organism responsible for many hospital-acquired infections. It is able to adhere to solid surfaces and develop an immobilized community or so-called biofilm. Many studies have been focusing on the use of specific materials to prevent the formation of these biofilms, but the reactivity of the bacteria in contact to surfaces remains unknown. The aim of this study was to evaluate the impact of the abiotic surface on the physiology of adherent bacteria. Three different materials, stainless steel (SS, glass (G, and polystyrene (PS that were relevant to industrial or medical environments were characterized at the physicochemical level in terms of their hydrophobicity and roughness. We showed that SS was moderately hydrophilic and rough, potentially containing crevices, G was hydrophilic and smooth while PS was hydrophobic and smooth. We further showed that P. aeruginosa cells were more likely able to adhere to SS and G rather than PS surfaces under our experimental conditions. The physiological response of P. aeruginosa when adhering to each of these materials was then evaluated by global proteomic analysis. The abundance of 70 proteins was shown to differ between the materials suggesting that their abundance was modified as a function of the material to which bacteria adhered. Our data lead to enabling the identification of abundance patterns that appeared to be specific to a given surface. Taken together, our data showed that P. aeruginosa is capable of sensing and responding to a surface probably via specific programmes to adapt its physiological response accordingly.

  20. Silicon Drift Detector response function for PIXE spectra fitting

    Science.gov (United States)

    Calzolai, G.; Tapinassi, S.; Chiari, M.; Giannoni, M.; Nava, S.; Pazzi, G.; Lucarelli, F.

    2018-02-01

    The correct determination of the X-ray peak areas in PIXE spectra by fitting with a computer program depends crucially on accurate parameterization of the detector peak response function. In the Guelph PIXE software package, GUPIXWin, one of the most used PIXE spectra analysis code, the response of a semiconductor detector to monochromatic X-ray radiation is described by a linear combination of several analytical functions: a Gaussian profile for the X-ray line itself, and additional tail contributions (exponential tails and step functions) on the low-energy side of the X-ray line to describe incomplete charge collection effects. The literature on the spectral response of silicon X-ray detectors for PIXE applications is rather scarce, in particular data for Silicon Drift Detectors (SDD) and for a large range of X-ray energies are missing. Using a set of analytical functions, the SDD response functions were satisfactorily reproduced for the X-ray energy range 1-15 keV. The behaviour of the parameters involved in the SDD tailing functions with X-ray energy is described by simple polynomial functions, which permit an easy implementation in PIXE spectra fitting codes.

  1. Surface functionalization of epitaxial graphene on SiC by ion irradiation for gas sensing application

    International Nuclear Information System (INIS)

    Kaushik, Priya Darshni; Ivanov, Ivan G.; Lin, Pin-Cheng; Kaur, Gurpreet; Eriksson, Jens; Lakshmi, G.B.V.S.; Avasthi, D.K.; Gupta, Vinay; Aziz, Anver; Siddiqui, Azher M.; Syväjärvi, Mikael; Yazdi, G. Reza

    2017-01-01

    Highlights: • For the first time the gas sensing application of SHI irradiated epitaxial graphene on SiC is explored. • Surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles. • Existence of an optimal fluence which maximize the gas sensing response towards NO_2 and NH_3 gases. - Abstract: In this work, surface functionalization of epitaxial graphene grown on silicon carbide was performed by ion irradiation to investigate their gas sensing capabilities. Swift heavy ion irradiation using 100 MeV silver ions at four varying fluences was implemented on epitaxial graphene to investigate morphological and structural changes and their effects on the gas sensing capabilities of graphene. Sensing devices are expected as one of the first electronic applications using graphene and most of them use functionalized surfaces to tailor a certain function. In our case, we have studied irradiation as a tool to achieve functionalization. Morphological and structural changes on epitaxial graphene layers were investigated by atomic force microscopy, Raman spectroscopy, Raman mapping and reflectance mapping. The surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles at highest fluence (2 × 10"1"3 ions/cm"2). Raman spectra analysis shows that the graphene defect density is increased with increasing fluence, while Raman mapping and reflectance mapping show that there is also a reduction of monolayer graphene coverage. The samples were investigated for ammonia and nitrogen dioxide gas sensing applications. Sensors fabricated on pristine and irradiated samples showed highest gas sensing response at an optimal fluence. Our work provides new pathways for introducing defects in controlled manner in epitaxial graphene, which can be used not only for gas sensing application but also for other applications, such as electrochemical, biosensing, magnetosensing and spintronic

  2. Surface functionalization of epitaxial graphene on SiC by ion irradiation for gas sensing application

    Energy Technology Data Exchange (ETDEWEB)

    Kaushik, Priya Darshni, E-mail: kaushik.priyadarshni@gmail.com [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Department of Physics, Jamia Millia Islamia, New Delhi, 110025 (India); Ivanov, Ivan G.; Lin, Pin-Cheng [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Kaur, Gurpreet [Department of Physics and Astrophysics, University of Delhi, Delhi, 110007 (India); Eriksson, Jens [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Lakshmi, G.B.V.S. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi, 110067 (India); Avasthi, D.K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi, 110067 (India); Amity Institute of Nanotechnology, Noida 201313 (India); Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi, 110007 (India); Aziz, Anver; Siddiqui, Azher M. [Department of Physics, Jamia Millia Islamia, New Delhi, 110025 (India); Syväjärvi, Mikael [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Yazdi, G. Reza, E-mail: yazdi@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden)

    2017-05-01

    Highlights: • For the first time the gas sensing application of SHI irradiated epitaxial graphene on SiC is explored. • Surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles. • Existence of an optimal fluence which maximize the gas sensing response towards NO{sub 2} and NH{sub 3} gases. - Abstract: In this work, surface functionalization of epitaxial graphene grown on silicon carbide was performed by ion irradiation to investigate their gas sensing capabilities. Swift heavy ion irradiation using 100 MeV silver ions at four varying fluences was implemented on epitaxial graphene to investigate morphological and structural changes and their effects on the gas sensing capabilities of graphene. Sensing devices are expected as one of the first electronic applications using graphene and most of them use functionalized surfaces to tailor a certain function. In our case, we have studied irradiation as a tool to achieve functionalization. Morphological and structural changes on epitaxial graphene layers were investigated by atomic force microscopy, Raman spectroscopy, Raman mapping and reflectance mapping. The surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles at highest fluence (2 × 10{sup 13} ions/cm{sup 2}). Raman spectra analysis shows that the graphene defect density is increased with increasing fluence, while Raman mapping and reflectance mapping show that there is also a reduction of monolayer graphene coverage. The samples were investigated for ammonia and nitrogen dioxide gas sensing applications. Sensors fabricated on pristine and irradiated samples showed highest gas sensing response at an optimal fluence. Our work provides new pathways for introducing defects in controlled manner in epitaxial graphene, which can be used not only for gas sensing application but also for other applications, such as electrochemical, biosensing, magnetosensing and

  3. Investigation of Tooling for Anisotropic Optical Functional Surfaces

    DEFF Research Database (Denmark)

    Li, Dongya; Regi, Francesco; Zhang, Yang

    This paper studied steel inserts with anisotropic surfaces for injection moulding. The inserts surfaces were machined by a five-axis micro-milling machine and the surface structures will be replicated by injection moulding. The aim of the surface structuring is to maximize visible contrast betwee...

  4. Science in Emergency Response at CDC: Structure and Functions.

    Science.gov (United States)

    Iskander, John; Rose, Dale A; Ghiya, Neelam D

    2017-09-01

    Recent high-profile activations of the US Centers for Disease Control and Prevention (CDC) Emergency Operations Center (EOC) include responses to the West African Ebola and Zika virus epidemics. Within the EOC, emergency responses are organized according to the Incident Management System, which provides a standardized structure and chain of command, regardless of whether the EOC activation occurs in response to an outbreak, natural disaster, or other type of public health emergency. By embedding key scientific roles, such as the associate director for science, and functions within a Scientific Response Section, the current CDC emergency response structure ensures that both urgent and important science issues receive needed attention. Key functions during emergency responses include internal coordination of scientific work, data management, information dissemination, and scientific publication. We describe a case example involving the ongoing Zika virus response that demonstrates how the scientific response structure can be used to rapidly produce high-quality science needed to answer urgent public health questions and guide policy. Within the context of emergency response, longer-term priorities at CDC include both streamlining administrative requirements and funding mechanisms for scientific research.

  5. Response surface analysis to improve dispersed crude oil biodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Zahed, Mohammad A.; Aziz, Hamidi A.; Mohajeri, Leila [School of Civil Engineering, Universiti Sains Malaysia, Nibong Tebal, Penang (Malaysia); Isa, Mohamed H. [Civil Engineering Department, Universiti Teknologi PETRONAS, Tronoh, Perak (Malaysia)

    2012-03-15

    In this research, the bioremediation of dispersed crude oil, based on the amount of nitrogen and phosphorus supplementation in the closed system, was optimized by the application of response surface methodology and central composite design. Correlation analysis of the mathematical-regression model demonstrated that a quadratic polynomial model could be used to optimize the hydrocarbon bioremediation (R{sup 2} = 0.9256). Statistical significance was checked by analysis of variance and residual analysis. Natural attenuation was removed by 22.1% of crude oil in 28 days. The highest removal on un-optimized condition of 68.1% were observed by using nitrogen of 20.00 mg/L and phosphorus of 2.00 mg/L in 28 days while optimization process exhibited a crude oil removal of 69.5% via nitrogen of 16.05 mg/L and phosphorus 1.34 mg/L in 27 days therefore optimization can improve biodegradation in shorter time with less nutrient consumption. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Optimization of composite flour biscuits by mixture response surface methodology.

    Science.gov (United States)

    Okpala, Laura C; Okoli, Eric C

    2013-08-01

    Biscuits were produced from blends of pigeon pea, sorghum and cocoyam flours. The study was carried out using mixture response surface methodology as the optimization technique. Using the simplex centroid design, 10 formulations were obtained. Protein and sensory quality of the biscuits were analyzed. The sensory attributes studied were appearance, taste, texture, crispness and general acceptability, while the protein quality indices were biological value and net protein utilization. The results showed that while the addition of pigeon pea improved the protein quality, its addition resulted in reduced sensory ratings for all the sensory attributes with the exception of appearance. Some of the biscuits had sensory ratings, which were not significantly different (p > 0.05) from biscuits made with wheat. Rat feeding experiments indicated that the biological value and net protein utilization values obtained for most of the biscuits were above minimum recommended values. Optimization suggested biscuits containing 75.30% sorghum, 0% pigeon pea and 24.70% cocoyam flours as the best proportion of these components. This sample received good scores for the sensory attributes.

  7. Optimization of vibratory welding process parameters using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Pravin Kumar; Kumar, S. Deepak; Patel, D.; Prasad, S. B. [National Institute of Technology Jamshedpur, Jharkhand (India)

    2017-05-15

    The current investigation was carried out to study the effect of vibratory welding technique on mechanical properties of 6 mm thick butt welded mild steel plates. A new concept of vibratory welding technique has been designed and developed which is capable to transfer vibrations, having resonance frequency of 300 Hz, into the molten weld pool before it solidifies during the Shielded metal arc welding (SMAW) process. The important process parameters of vibratory welding technique namely welding current, welding speed and frequency of the vibrations induced in molten weld pool were optimized using Taguchi’s analysis and Response surface methodology (RSM). The effect of process parameters on tensile strength and hardness were evaluated using optimization techniques. Applying RSM, the effect of vibratory welding parameters on tensile strength and hardness were obtained through two separate regression equations. Results showed that, the most influencing factor for the desired tensile strength and hardness is frequency at its resonance value, i.e. 300 Hz. The micro-hardness and microstructures of the vibratory welded joints were studied in detail and compared with those of conventional SMAW joints. Comparatively, uniform and fine grain structure has been found in vibratory welded joints.

  8. Mitochondrial respiration controls lysosomal function during inflammatory T cell responses

    Science.gov (United States)

    Baixauli, Francesc; Acín-Pérez, Rebeca; Villarroya-Beltrí, Carolina; Mazzeo, Carla; Nuñez-Andrade, Norman; Gabandé-Rodriguez, Enrique; Dolores Ledesma, Maria; Blázquez, Alberto; Martin, Miguel Angel; Falcón-Pérez, Juan Manuel; Redondo, Juan Miguel; Enríquez, Jose Antonio; Mittelbrunn, Maria

    2016-01-01

    Summary The endolysosomal system is critical for the maintenance of cellular homeostasis. However, how endolysosomal compartment is regulated by mitochondrial function is largely unknown. We have generated a mouse model with defective mitochondrial function in CD4+ T lymphocytes by genetic deletion of the mitochondrial transcription factor A (Tfam). Mitochondrial respiration-deficiency impairs lysosome function, promotes p62 and sphingomyelin accumulation and disrupts endolysosomal trafficking pathways and autophagy, thus linking a primary mitochondrial dysfunction to a lysosomal storage disorder. The impaired lysosome function in Tfam-deficient cells subverts T cell differentiation toward pro-inflammatory subsets and exacerbates the in vivo inflammatory response. Restoration of NAD+ levels improves lysosome function and corrects the inflammatory defects in Tfam-deficient T cells. Our results uncover a mechanism by which mitochondria regulate lysosome function to preserve T cell differentiation and effector functions, and identify novel strategies for intervention in mitochondrial-related diseases. PMID:26299452

  9. Local and linear chemical reactivity response functions at finite temperature in density functional theory

    International Nuclear Information System (INIS)

    Franco-Pérez, Marco; Ayers, Paul W.; Gázquez, José L.; Vela, Alberto

    2015-01-01

    We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model

  10. Reliability Evaluation of Bridges Based on Nonprobabilistic Response Surface Limit Method

    Directory of Open Access Journals (Sweden)

    Xuyong Chen

    2017-01-01

    Full Text Available Due to many uncertainties in nonprobabilistic reliability assessment of bridges, the limit state function is generally unknown. The traditional nonprobabilistic response surface method is a lengthy and oscillating iteration process and leads to difficultly solving the nonprobabilistic reliability index. This article proposes a nonprobabilistic response surface limit method based on the interval model. The intention of this method is to solve the upper and lower limits of the nonprobabilistic reliability index and to narrow the range of the nonprobabilistic reliability index. If the range of the reliability index reduces to an acceptable accuracy, the solution will be considered convergent, and the nonprobabilistic reliability index will be obtained. The case study indicates that using the proposed method can avoid oscillating iteration process, make iteration process stable and convergent, reduce iteration steps significantly, and improve computational efficiency and precision significantly compared with the traditional nonprobabilistic response surface method. Finally, the nonprobabilistic reliability evaluation process of bridge will be built through evaluating the reliability of one PC continuous rigid frame bridge with three spans using the proposed method, which appears to be more simple and reliable when lack of samples and parameters in the bridge nonprobabilistic reliability evaluation is present.

  11. Artificial Intelligence Mechanisms on Interactive Modified Simplex Method with Desirability Function for Optimising Surface Lapping Process

    Directory of Open Access Journals (Sweden)

    Pongchanun Luangpaiboon

    2014-01-01

    Full Text Available A study has been made to optimise the influential parameters of surface lapping process. Lapping time, lapping speed, downward pressure, and charging pressure were chosen from the preliminary studies as parameters to determine process performances in terms of material removal, lap width, and clamp force. The desirability functions of the-nominal-the-best were used to compromise multiple responses into the overall desirability function level or D response. The conventional modified simplex or Nelder-Mead simplex method and the interactive desirability function are performed to optimise online the parameter levels in order to maximise the D response. In order to determine the lapping process parameters effectively, this research then applies two powerful artificial intelligence optimisation mechanisms from harmony search and firefly algorithms. The recommended condition of (lapping time, lapping speed, downward pressure, and charging pressure at (33, 35, 6.0, and 5.0 has been verified by performing confirmation experiments. It showed that the D response level increased to 0.96. When compared with the current operating condition, there is a decrease of the material removal and lap width with the improved process performance indices of 2.01 and 1.14, respectively. Similarly, there is an increase of the clamp force with the improved process performance index of 1.58.

  12. Functional neural networks underlying response inhibition in adolescents and adults.

    Science.gov (United States)

    Stevens, Michael C; Kiehl, Kent A; Pearlson, Godfrey D; Calhoun, Vince D

    2007-07-19

    This study provides the first description of neural network dynamics associated with response inhibition in healthy adolescents and adults. Functional and effective connectivity analyses of whole brain hemodynamic activity elicited during performance of a Go/No-Go task were used to identify functionally integrated neural networks and characterize their causal interactions. Three response inhibition circuits formed a hierarchical, inter-dependent system wherein thalamic modulation of input to premotor cortex by fronto-striatal regions led to response suppression. Adolescents differed from adults in the degree of network engagement, regional fronto-striatal-thalamic connectivity, and network dynamics. We identify and characterize several age-related differences in the function of neural circuits that are associated with behavioral performance changes across adolescent development.

  13. Response variance in functional maps: neural darwinism revisited.

    Directory of Open Access Journals (Sweden)

    Hirokazu Takahashi

    Full Text Available The mechanisms by which functional maps and map plasticity contribute to cortical computation remain controversial. Recent studies have revisited the theory of neural Darwinism to interpret the learning-induced map plasticity and neuronal heterogeneity observed in the cortex. Here, we hypothesize that the Darwinian principle provides a substrate to explain the relationship between neuron heterogeneity and cortical functional maps. We demonstrate in the rat auditory cortex that the degree of response variance is closely correlated with the size of its representational area. Further, we show that the response variance within a given population is altered through training. These results suggest that larger representational areas may help to accommodate heterogeneous populations of neurons. Thus, functional maps and map plasticity are likely to play essential roles in Darwinian computation, serving as effective, but not absolutely necessary, structures to generate diverse response properties within a neural population.

  14. Response variance in functional maps: neural darwinism revisited.

    Science.gov (United States)

    Takahashi, Hirokazu; Yokota, Ryo; Kanzaki, Ryohei

    2013-01-01

    The mechanisms by which functional maps and map plasticity contribute to cortical computation remain controversial. Recent studies have revisited the theory of neural Darwinism to interpret the learning-induced map plasticity and neuronal heterogeneity observed in the cortex. Here, we hypothesize that the Darwinian principle provides a substrate to explain the relationship between neuron heterogeneity and cortical functional maps. We demonstrate in the rat auditory cortex that the degree of response variance is closely correlated with the size of its representational area. Further, we show that the response variance within a given population is altered through training. These results suggest that larger representational areas may help to accommodate heterogeneous populations of neurons. Thus, functional maps and map plasticity are likely to play essential roles in Darwinian computation, serving as effective, but not absolutely necessary, structures to generate diverse response properties within a neural population.

  15. Dual-responsive surfaces modified with phenylboronic acid-containing polymer brush to reversibly capture and release cancer cells.

    Science.gov (United States)

    Liu, Hongliang; Li, Yingying; Sun, Kang; Fan, Junbing; Zhang, Pengchao; Meng, Jingxin; Wang, Shutao; Jiang, Lei

    2013-05-22

    Artificial stimuli-responsive surfaces that can mimic the dynamic function of living systems have attracted much attention. However, there exist few artificial systems capable of responding to dual- or multistimulation as the natural system does. Herein, we synthesize a pH and glucose dual-responsive surface by grafting poly(acrylamidophenylboronic acid) (polyAAPBA) brush from aligned silicon nanowire (SiNW) array. The as-prepared surface can reversibly capture and release targeted cancer cells by precisely controlling pH and glucose concentration, exhibiting dual-responsive AND logic. In the presence of 70 mM glucose, the surface is pH responsive, which can vary from a cell-adhesive state to a cell-repulsive state by changing the pH from 6.8 to 7.8. While keeping the pH at 7.8, the surface becomes glucose responsive--capturing cells in the absence of glucose and releasing cells by adding 70 mM glucose. Through simultaneously changing the pH and glucose concentration from pH 6.8/0 mM glucose to pH 7.8/70 mM glucose, the surface is dual responsive with the capability to switch between cell capture and release for at least 5 cycles. The cell capture and release process on this dual-responsive surface is noninvasive with cell viability higher than 95%. Moreover, topographical interaction between the aligned SiNW array and cell protrusions greatly amplifies the responsiveness and accelerates the response rate of the dual-responsive surface between cell capture and release. The responsive mechanism of the dual-responsive surface is systematically studied using a quartz crystal microbalance, which shows that the competitive binding between polyAAPBA/sialic acid and polyAAPBA/glucose contributes to the dual response. Such dual-responsive surface can significantly impact biomedical and biological applications including cell-based diagnostics, in vivo drug delivery, etc.

  16. Functionally unidimensional item response models for multivariate binary data

    DEFF Research Database (Denmark)

    Ip, Edward; Molenberghs, Geert; Chen, Shyh-Huei

    2013-01-01

    The problem of fitting unidimensional item response models to potentially multidimensional data has been extensively studied. The focus of this article is on response data that have a strong dimension but also contain minor nuisance dimensions. Fitting a unidimensional model to such multidimensio......The problem of fitting unidimensional item response models to potentially multidimensional data has been extensively studied. The focus of this article is on response data that have a strong dimension but also contain minor nuisance dimensions. Fitting a unidimensional model...... to such multidimensional data is believed to result in ability estimates that represent a combination of the major and minor dimensions. We conjecture that the underlying dimension for the fitted unidimensional model, which we call the functional dimension, represents a nonlinear projection. In this article we investigate...... tool. An example regarding a construct of desire for physical competency is used to illustrate the functional unidimensional approach....

  17. Using the Geminids to Characterize the Surface Response of an Airless Body to Meteoroid Bombardment

    Science.gov (United States)

    Szalay, J.; Pokorny, P.; Jenniskens, P. M. M.; Horanyi, M.

    2017-12-01

    All airless bodies in the solar system are exposed to the continual bombardment by interplanetary meteoroids. These impacts can eject orders of magnitude more mass than the primary impactors, sustaining bound and/or unbound ejecta clouds that vary both spatially and temporally from changes in impactor fluxes. The dust environment in the vicinity of an airless body provides both a scientific resource and a hazard for exploration. Characterizing the spatial and temporal variability of the dust environment of airless planetary bodies provides a novel way to understand their meteoroid environment by effectively using these objects as large surface area meteoroid detectors. Additionally, were a dust detector with chemical sensing capability to be flown near such a body, it would be able to directly measure the composition of the body without requiring the mission design complexity involved in landing and sampling surface material. Paramount to understanding the current and future impact ejecta measurements is a sufficient understanding of the impact ejecta processes at the surface. In this presentation, we focus on data taken by the Lunar Dust Experiment (LDEX), an impact ionization dust detector onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission, designed to measure impact ejecta around the Moon. We use the Geminids meteoroid shower as a well constrained input function, and via comparison to existing ground-based measurements of this shower, to "calibrate" the response of the lunar surface to meteoroid bombardment. Understanding the response of the lunar surface to meteoroid bombardment can by extension allow us to better understand the ejecta response at other regolith airless bodies in the solar system. Future missions equipped with dust detectors sent to the Moon, large Near Earth Asteroids, the Martian moons Phobos and Deimos, or many other airless bodies in the solar system would greatly improve our knowledge of their local meteoroid

  18. Direct quantification of negatively charged functional groups on membrane surfaces

    KAUST Repository

    Tiraferri, Alberto; Elimelech, Menachem

    2012-01-01

    groups at the surface of dense polymeric membranes. Both techniques consist of associating the membrane surface moieties with chemical probes, followed by quantification of the bound probes. Uranyl acetate and toluidine blue O dye, which interact

  19. Testing of newly developed functional surfaces under pure sliding conditions

    DEFF Research Database (Denmark)

    Godi, Alessandro; Mohaghegh, Kamran; Grønbæk, J.

    2013-01-01

    the surfaces in an industrial context. In this paper, a number of experimental tests were performed using a novel test rig, called axial sliding test, simulating the contact of surfaces under pure sliding conditions. The aim of the experiments is to evaluate the frictional behavior of a new typology...... of textured surfaces, the so-called multifunctional surfaces, characterized by a plateau area able to bear loads and a deterministic pattern of lubricant pockets. Six surface typologies, namely three multifunctional and three machined using classical processes, were chosen to slide against a mirror....... The results comparison showed clearly how employing multifunctional surfaces can reduce friction forces up to 50 % at high normal loads compared to regularly ground or turned surfaces. Friction coefficients approximately equal to 0.12 were found for classically machined surfaces, whereas the values were 0...

  20. MACK/MACKLIB system for nuclear response functions

    International Nuclear Information System (INIS)

    Abdou, M.A.; Gohar, Y.

    1978-01-01

    The MACK computer program calculates energy pointwise and multigroup nuclear response functions from basic nuclear data in ENDF/B format. The new version of the program, MACK-IV, incorporates major developments and improvements aimed at maximizing the utilization of available nuclear data and ensuring energy conservation in nuclear heating calculations. A new library, MACKLIB-IV, of nuclear response functions was generated in the CTR energy group structure of 171 neutron groups and 36 gamma groups. The library was prepared using MACK-IV, and ENDF/B-IV, and is suitable for fusion, fusion--fission hybrids, and fission applications. 3 figures, 4 tables

  1. MACK/MACKLIB system for nuclear response functions

    International Nuclear Information System (INIS)

    Abdou, M.A.; Gohar, Y.M.

    1978-01-01

    The MACK computer program calculates energy pointwise and multigroup nuclear response functions from basic nuclear data in ENDF/B format. The new version of the program MACK-IV, incorporates major developments and improvements aimed at maximizing the utilization of available nuclear data and ensuring energy conservation in nuclear heating calculations. A new library, MACKLIB-IV, of nuclear response functions was generated in the CTR energy group structure of 171 neutron groups and 36 gamma groups. The library was prepared using MACK-IV and ENDF/B-IV and is suitable for fusion, fusion-fission hydrids, and fission applications

  2. Computations of nuclear response functions with MACK-IV

    International Nuclear Information System (INIS)

    Abdou, M.A.; Gohar, Y.

    1978-01-01

    The MACK computer program calculates energy pointwise and multigroup nuclear response functions from basic nuclear data in ENDF/B format. The new version of the program, MACK-IV, incorporates major developments and improvements aimed at maximizing the utilization of available nuclear data and ensuring energy conservation in nuclear heating calculations. A new library, MACKLIB-IV, of nuclear response functions was generated in the CTR energy group structure of 171 neutron groups and 36 gamma groups. The library was prepared using MACK-IV and ENDF/B-IV and is suitable for fusion, fusion-fission hybrids, and fission applications

  3. Computations of nuclear response functions with MACK-IV

    Energy Technology Data Exchange (ETDEWEB)

    Abdou, M A; Gohar, Y

    1978-01-01

    The MACK computer program calculates energy pointwise and multigroup nuclear response functions from basic nuclear data in ENDF/B format. The new version of the program, MACK-IV, incorporates major developments and improvements aimed at maximizing the utilization of available nuclear data and ensuring energy conservation in nuclear heating calculations. A new library, MACKLIB-IV, of nuclear response functions was generated in the CTR energy group structure of 171 neutron groups and 36 gamma groups. The library was prepared using MACK-IV and ENDF/B-IV and is suitable for fusion, fusion-fission hybrids, and fission applications.

  4. MACK/MACKLIB system for nuclear response functions

    Energy Technology Data Exchange (ETDEWEB)

    Abdou, M.A.; Gohar, Y.M.

    1978-03-15

    The MACK computer program calculates energy pointwise and multigroup nuclear response functions from basic nuclear data in ENDF/B format. The new version of the program MACK-IV, incorporates major developments and improvements aimed at maximizing the utilization of available nuclear data and ensuring energy conservation in nuclear heating calculations. A new library, MACKLIB-IV, of nuclear response functions was generated in the CTR energy group structure of 171 neutron groups and 36 gamma groups. The library was prepared using MACK-IV and ENDF/B-IV and is suitable for fusion, fusion-fission hydrids, and fission applications.

  5. Functional criteria for emergency response facilities. Technical report (final)

    International Nuclear Information System (INIS)

    1981-02-01

    This report describes the facilities and systems to be used by nuclear power plant licensees to improve responses to emergency situations. The facilities include the Technical Support Center (TSC), Onsite Operational Support Center (OSC), and Nearsite Emergency Operations Facility (EOF), as well as a brief discussion of the emergency response function of the control room. The data systems described are the Safety Parameter Display System (SPDS) and Nuclear Data Link (NDL). Together, these facilities and systems make up the total Emergency Response Facilities (ERFs). Licensees should follow the guidance provided both in this report and in NUREG-0654 (FEMA-REP-1), Revision 1, for design and implementation of the ERFs

  6. Interpolation of magnetic surface functions for an axi-symmetric plasma

    International Nuclear Information System (INIS)

    Yamaguchi, Taiki; Maeyama, Mitsuaki

    2000-01-01

    Informations of the magnetic surface functions of magnetically confined plasma are indispensable for equilibrium, stability and transport analyses. In this paper, in order to identify a realistic surface functions and compare those with ones which are introduced from Taylor's relaxation theory, we propose a code to interpolate these surface functions for an axi-symmetric plasma from experimentally measured data. To confirm our code, we used the date which were analyzed from known functions given as a measured data. As a result, we have developed a code which can derive surface functions I and P. Effects of measurement error on those functions are also examined. (author)

  7. Synthesis of Environmentally Responsive Polymers by Atom Transfer Radical Polymerization: Generation of Reversible Hydrophilic and Hydrophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Vikas Mittal

    2010-05-01

    Full Text Available Environmentally responsive poly(N-isopropylacrylamide brushes were grafted from the surface of polymer particles or flat surfaces in order to generate reversible hydrophilic and hydrophobic surfaces. The use of atom transfer radical polymerization was demonstrated for the grafting of polymer brushes as it allows efficient control on the amount of grafted polymer. The polymer particles were generated with or without surfactant in the emulsion polymerization and their surface could be modified with the atom transfer radical polymerization (ATRP initiator. The uniform functionalization of the surface with ATRP initiator was responsible for the uniform grafting of polymer brushes. The grafted brushes responded reversibly with changes in temperature indicating that the reversible responsive behavior could be translated to the particle surfaces. The particles were observed to adsorb and desorb protein and virus molecules by changing the temperatures below or higher than 32 °C. The initiator functionalized particles could also be adsorbed on the flat surfaces. The adsorption process also required optimization of the heat treatment conditions to form a uniform layer of the particles on the substrate. The grafted polymer brushes also responded to the changes in temperatures similar to the spherical particles studied through water droplets placed on the flat substrates.

  8. Improved low frequency room responses by considering finiteness of room boundary surfaces

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2013-01-01

    surface impedance values that are assigned to all the boundary surfaces, the suggested reflection coefficient is found to improve low frequency responses compared to the infinite panel theory; larger improvements are found for a more disproportionate room, more absorptive surfaces, and surfaces having...

  9. Frequency response in surface-potential driven electrohydrodynamics

    DEFF Research Database (Denmark)

    Ejsing, Louise Wellendorph; Smistrup, Kristian; Pedersen, Christian Møller

    2006-01-01

    Using a Fourier approach we offer a general solution to calculations of slip velocity within the circuit description of the electrohydrodynamics in a binary electrolyte confined by a plane surface with a modulated surface potential. We consider the case with a spatially constant intrinsic surface...... capacitance where the net flow rate is, in general, zero while harmonic rolls as well as time-averaged vortexlike components may exist depending on the spatial symmetry and extension of the surface potential. In general, the system displays a resonance behavior at a frequency corresponding to the inverse RC...

  10. Functional MRI of food-induced brain responses

    NARCIS (Netherlands)

    Smeets, P.A.M.

    2006-01-01

    The ultimate goal of this research was to find central biomarkers of satiety, i.e., physiological measures in the brain that relate to subjectively rated appetite, actual food intake, or both. This thesis describes the changes in brain activity in response to food stimuli as measured by functional

  11. Semiparametric Item Response Functions in the Context of Guessing

    Science.gov (United States)

    Falk, Carl F.; Cai, Li

    2016-01-01

    We present a logistic function of a monotonic polynomial with a lower asymptote, allowing additional flexibility beyond the three-parameter logistic model. We develop a maximum marginal likelihood-based approach to estimate the item parameters. The new item response model is demonstrated on math assessment data from a state, and a computationally…

  12. Fitting of transfer functions to frequency response measurements

    International Nuclear Information System (INIS)

    Moret, J.M.

    1994-12-01

    An algorithm for approximating a given complex frequency response with a rational function of two polynomials with real coefficients is presented, together with its extension to distributed parameter systems, the corresponding error analysis and its application to a real case. (author) 5 figs., 4 refs

  13. Functionalized mesoporous silica nanoparticles for stimuli-responsive and targeted

    Energy Technology Data Exchange (ETDEWEB)

    Knezevic, Nikola [Iowa State Univ., Ames, IA (United States)

    2009-12-15

    Construction of functional supramolecular nanoassemblies has attracted great deal of attention in recent years for their wide spectrum of practical applications. Mesoporous silica nanoparticles (MSN) in particular were shown to be effective scaffolds for the construction of drug carriers, sensors and catalysts. Herein, we describe the synthesis and characterization of stimuli-responsive, controlled release MSN-based assemblies for drug delivery.

  14. Response efficiency during functional communication training: effects of effort on response allocation.

    OpenAIRE

    Richman, D M; Wacker, D P; Winborn, L

    2001-01-01

    An analogue functional analysis revealed that the problem behavior of a young child with developmental delays was maintained by positive reinforcement. A concurrent-schedule procedure was then used to vary the amount of effort required to emit mands. Results suggested that response effort can be an important variable when developing effective functional communication training programs.

  15. A Smart Superwetting Surface with Responsivity in Both Surface Chemistry and Microstructure.

    Science.gov (United States)

    Zhang, Dongjie; Cheng, Zhongjun; Kang, Hongjun; Yu, Jianxin; Liu, Yuyan; Jiang, Lei

    2018-03-26

    Recently, smart surfaces with switchable wettability have aroused much attention. However, only single surface chemistry or the microstructure can be changed on these surfaces, which significantly limits their wetting performances, controllability, and applications. A new surface with both tunable surface microstructure and chemistry was prepared by grafting poly(N-isopropylacrylamide) onto the pillar-structured shape memory polymer on which multiple wetting states from superhydrophilicity to superhydrophobicity can be reversibly and precisely controlled by synergistically regulating the surface microstructure and chemistry. Meanwhile, based on the excellent controllability, we also showed the application of the surface as a rewritable platform, and various gradient wettings can be obtained. This work presents for the first time a surface with controllability in both surface chemistry and microstructure, which starts some new ideas for the design of novel superwetting materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. OPTIMIZATION OF SURFACE RESISTIVITY AND RELATIVE PERMITTIVITY OF SILICONE RUBBER FOR HIGH VOLTAGE APPLICATION USING RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    N.N. Ali

    2017-06-01

    Full Text Available Silicone Rubber (SiR is considered as one of the most established insulator in High Voltage (HV industry. SiR possess a great function ability such as its lighter weight, great heat resistance and substantial electrical insulation properties. Dynamic research were performed all around the world in order to explore the unique insulating behavior of SiR but very little are done on the optimization of SiR in term of their processing parameters and formulation. In this work, four materials and processing factors were introduced; A: Alumina Trihydrate (ATH, B: Dicumyl-Peroxide (DCP, C: mixing speed and D: mixing time in order to analyze its contribution towards improving the surface resistivity and relative permittivity of SIR rubber. The factors range were set based on prior screening and are defined as; ATH (10 – 50 pphr, Dicumyl Peroxide (0.50 -1.50 pphr, speed of mixer (40 – 70 rpm and mixing period (5 – 10 mins which were then varied accordingly to produce an overall 19 samples of SiR blends. The testing results were analyzed using statistical Design of Experiment (DOE by applying two level full factorial from Design Expert Software (v10 to discover the inter-correlation between the factors studied and benefaction of each factor in improving both surface resistivity and relative permittivity responses of produced SiR blends. The model analysis on surface resistivity shows the coefficient of determination R2 value of 88.72% while the one for relative permittivity shows R2 value of 82.34 %. Combination of both dependent variables had yielded an optimization suggestion for SiR formulation and processing strategy of ATH: 50 pphr, DCP: 0.50 pphr, mixing speed: 70 rpm and mixing period: 10 mins with the desirability level of 0.835. The optimized formulation had resulted in the production of SiR blend with the characteristic of surface resistivity of 1.02039x10^14 Ω/sq and relative permittivity of 4.0231, respectively. In conclusion, it can be

  17. Conceptual DFT: the chemical relevance of higher response functions.

    Science.gov (United States)

    Geerlings, P; De Proft, F

    2008-06-07

    In recent years conceptual density functional theory offered a perspective for the interpretation/prediction of experimental/theoretical reactivity data on the basis of a series of response functions to perturbations in the number of electrons and/or external potential. This approach has enabled the sharp definition and computation, from first principles, of a series of well-known but sometimes vaguely defined chemical concepts such as electronegativity and hardness. In this contribution, a short overview of the shortcomings of the simplest, first order response functions is illustrated leading to a description of chemical bonding in a covalent interaction in terms of interacting atoms or groups, governed by electrostatics with the tendency to polarize bonds on the basis of electronegativity differences. The second order approach, well known until now, introduces the hardness/softness and Fukui function concepts related to polarizability and frontier MO theory, respectively. The introduction of polarizability/softness is also considered in a historical perspective in which polarizability was, with some exceptions, mainly put forward in non covalent interactions. A particular series of response functions, arising when the changes in the external potential are solely provoked by changes in nuclear configurations (the "R-analogues") are also systematically considered. The main part of the contribution is devoted to third order response functions which, at first sight, may be expected not to yield chemically significant information, as turns out to be for the hyperhardness. A counterexample is the dual descriptor and its R analogue, the initial hardness response, which turns out to yield a firm basis to regain the Woodward-Hoffmann rules for pericyclic reactions based on a density-only basis, i.e. without involving the phase, sign, symmetry of the wavefunction. Even the second order nonlinear response functions are shown possibly to bear interesting information, e

  18. Response functions for infinite fermion systems with velocity dependent interactions

    International Nuclear Information System (INIS)

    Garcia-Recio, C.; Salcedo, L.L.; Navarro, J.; Nguyen Van Giai

    1991-01-01

    Response functions of infinite Fermi systems are studied in the framework of the self-consistent Random Phase Approximation. Starting from an effective interaction with velocity and density dependence, or equivalently from a local energy density functional, algebraic expressions for the RPA response function are derived. Simple formulae for the energy-weighted and polarizability sum rules are obtained. The method is illustrated by applications to nuclear matter and liquid 3 He. In nuclear matter, it is shown that existing Skyrme interactions give spin-isospin response functions close to those calculated with finite range interactions. The different renormalization of longitudinal and transverse Coulomb sum rules in nuclear matter is discussed. In 3 He, the low-lying collective spin oscillation can be well described in a wide range of momenta with a Skyrme-type interaction if the relevant Landau parameters are fitted. For the high-lying density oscillation, the introduction of a finite range term in the energy functional improves considerably the agreement with the data. (author) 54 refs., 19 figs., 4 tabs

  19. Optimal hemodynamic response model for functional near-infrared spectroscopy

    Directory of Open Access Journals (Sweden)

    Muhammad Ahmad Kamran

    2015-06-01

    Full Text Available Functional near-infrared spectroscopy (fNIRS is an emerging non-invasive brain imaging technique and measures brain activities by means of near-infrared light of 650-950 nm wavelengths. The cortical hemodynamic response (HR differs in attributes at different brain regions and on repetition of trials, even if the experimental paradigm is kept exactly the same. Therefore, an HR model that can estimate such variations in the response is the objective of this research. The canonical hemodynamic response function (cHRF is modeled by using two Gamma functions with six unknown parameters. The HRF model is supposed to be linear combination of HRF, baseline and physiological noises (amplitudes and frequencies of physiological noises are supposed to be unknown. An objective function is developed as a square of the residuals with constraints on twelve free parameters. The formulated problem is solved by using an iterative optimization algorithm to estimate the unknown parameters in the model. Inter-subject variations in HRF and physiological noises have been estimated for better cortical functional maps. The accuracy of the algorithm has been verified using ten real and fifteen simulated data sets. Ten healthy subjects participated in the experiment and their HRF for finger-tapping tasks have been estimated and analyzed. The statistical significance of the estimated activity strength parameters has been verified by employing statistical analysis, i.e., (t-value >tcritical and p-value < 0.05.

  20. Magneto-optical response of Cu/NiFe/Cu nanostructure under surface plasmon resonance

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoodi, S. [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, 87317 (Iran, Islamic Republic of); Moradi, M., E-mail: m.moradi@kashanu.ac.ir [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, 87317 (Iran, Islamic Republic of); Mohseni, S.M. [Department of Physics, Shahid Beheshti University, Evin, Tehran, 19839 (Iran, Islamic Republic of)

    2016-12-15

    In this paper, we present theoretical and experimental studies about the surface plasmon resonance effects on the magneto-optical activity of Cu/NiFe/Cu nanostructures as a function of layers thickness and light incident angle. Device fabrication was done by an oblique deposition technique with RF magnetron sputtering to carefully cover fine step thickness variation of all constituted layers. Angular dependent transverse Kerr response of samples was measured in the Kretschmann configuration at a fixed wavelength of 632 nm. At an optimum layer thickness and incident angle, significant amplification of the transverse Kerr effect was observed. Enhancement in the transverse Kerr effect can be realized by hybridization of surface plasmon excitation and cavity resonance in the plasmonic nanostructure. Experimental results were in qualitative agreement with modeling based on the 4×4 transfer matrix formalism. - Highlights: • Large magneto-optical response in Cu/NiFe/Cu multilayer nanostructure is achieved. • Layer thickness and sequence are studied to find large transverse Kerr signal. • Hybridization of surface plasmon excitation and cavity resonance were done.

  1. Selective adsorption of oppositely charged PNIPAAM on halloysite surfaces: a route to thermo-responsive nanocarriers.

    Science.gov (United States)

    Cavallaro, Giuseppe; Lazzara, Giuseppe; Lisuzzo, Lorenzo; Milioto, Stefana; Parisi, Filippo

    2018-05-17

    Halloysite nanotubes were functionalized with stimuli-responsive macromolecules to generate smart nanohybrids. Poly(N-isopropylacrylamide)-co-methacrylic acid (PNIPAAM-co-MA) was selectively adsorbed into halloysite lumen by exploiting electrostatic interactions. Amine-terminated PNIPAAM polymer was also investigated that selectively interacts with the outer surface of the nanotubes. The adsorption site has a profound effect on the thermodynamic behavior and therefore temperature responsive features of the hybrid material. The drug release kinetics was investigated by using Diclofenac as a non-steroidal anti-inflammatory drug model. The release kinetics depends on the nanoarchitecture of the PNIPAAM/Halloysite based material. In particular, diclofenac release was slowed down above the LCST for PNIPAAM-co-MA/Halloysite. Opposite trends occurred for Halloysite functionalized with PNIPAAM at the outer surface. This work represents a further step toward the opportunity to extend and control the delivery conditions of active species, which represent a key point in technological applications. © 2018 IOP Publishing Ltd.

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

    Science.gov (United States)

    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.

  3. Stimulus-response functions of single avian olfactory bulb neurones.

    Science.gov (United States)

    McKeegan, Dorothy E F; Demmers, Theodorus G M; Wathes, Christopher M; Jones, R Bryan; Gentle, Michael J

    2002-10-25

    This study investigated olfactory processing in a functional context by examining the responses of single avian olfactory bulb neurones to two biologically important gases over relevant concentration ranges. Recordings of extracellular spike activity were made from 80 single units in the left olfactory bulb of 11 anaesthetised, freely breathing adult hens (Gallus domesticus). The units were spontaneously active, exhibiting widely variable firing rates (0.07-47.28 spikes/s) and variable temporal firing patterns. Single units were tested for their response to an ascending concentration series of either ammonia (2.5-100 ppm) or hydrogen sulphide (1-50 ppm), delivered directly to the olfactory epithelium. Stimulation with a calibrated gas delivery system resulted in modification of spontaneous activity causing either inhibition (47% of units) or excitation (53%) of firing. For ammonia, 20 of the 35 units tested exhibited a response, while for hydrogen sulphide, 25 of the 45 units tested were responsive. Approximate response thresholds for ammonia (median threshold 3.75 ppm (range 2.5-60 ppm, n=20)) and hydrogen sulphide (median threshold 1 ppm (range 1-10 ppm, n=25)) were determined with most units exhibiting thresholds near the lower end of these ranges. Stimulus response curves were constructed for 23 units; 16 (the most complete) were subjected to a linear regression analysis to determine whether they were best fitted by a linear, log or power function. No single function provided the best fit for all the curves (seven were linear, eight were log, one was power). These findings show that avian units respond to changes in stimulus concentration in a manner generally consistent with reported responses in mammalian olfactory bulb neurones. However, this study illustrates a level of fine-tuning to small step changes in concentration (<5 ppm) not previously demonstrated in vertebrate single olfactory bulb neurones.

  4. Determination of Critical Conditions for Puncturing Almonds Using Coupled Response Surface Methodology and Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Mahmood Mahmoodi-Eshkaftaki

    2013-01-01

    Full Text Available In this study, the effect of seed moisture content, probe diameter and loading velocity (puncture conditions on some mechanical properties of almond kernel and peeled almond kernel is considered to model a relationship between the puncture conditions and rupture energy. Furthermore, distribution of the mechanical properties is determined. The main objective is to determine the critical values of mechanical properties significant for peeling machines. The response surface methodology was used to find the relationship between the input parameters and the output responses, and the fitness function was applied to measure the optimal values using the genetic algorithm. Two-parameter Weibull function was used to describe the distribution of mechanical properties. Based on the Weibull parameter values, i.e. shape parameter (β and scale parameter (η calculated for each property, the mechanical distribution variations were completely described and it was confirmed that the mechanical properties are rule governed, which makes the Weibull function suitable for estimating their distributions. The energy model estimated using response surface methodology shows that the mechanical properties relate exponentially to the moisture, and polynomially to the loading velocity and probe diameter, which enabled successful estimation of the rupture energy (R²=0.94. The genetic algorithm calculated the critical values of seed moisture, probe diameter, and loading velocity to be 18.11 % on dry mass basis, 0.79 mm, and 0.15 mm/min, respectively, and optimum rupture energy of 1.97·10-³ J. These conditions were used for comparison with new samples, where the rupture energy was experimentally measured to be 2.68 and 2.21·10-³ J for kernel and peeled kernel, respectively, which was nearly in agreement with our model results.

  5. Precision Interval Estimation of the Response Surface by Means of an Integrated Algorithm of Neural Network and Linear Regression

    Science.gov (United States)

    Lo, Ching F.

    1999-01-01

    The integration of Radial Basis Function Networks and Back Propagation Neural Networks with the Multiple Linear Regression has been accomplished to map nonlinear response surfaces over a wide range of independent variables in the process of the Modem Design of Experiments. The integrated method is capable to estimate the precision intervals including confidence and predicted intervals. The power of the innovative method has been demonstrated by applying to a set of wind tunnel test data in construction of response surface and estimation of precision interval.

  6. Osteoblast response to zirconia surfaces with different topographies

    Energy Technology Data Exchange (ETDEWEB)

    Herath, H.M.T.U. [Department of Medical Laboratory Science, Faculty of Allied Health Sciences, University of Peradeniya (Sri Lanka); Di Silvio, L. [Guy' s, King' s and St Thomas' Medical and Dental Institute, King' s College London, London SE1 9RT (United Kingdom); Evans, J.R.G., E-mail: j.r.g.evans@ucl.ac.uk [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2015-12-01

    Zirconia-3 mol% yttria ceramics were prepared with as-sintered, abraded, polished, and porous surfaces in order to explore the attachment, proliferation and differentiation of osteoblast-like cells. After modification, all surfaces were heated to 600 °C to extinguish traces of organic contamination. All surfaces supported cell attachment, proliferation and differentiation but the surfaces with grain boundary grooves or abraded grooves provided conditions for enhanced initial cell attachment. Nevertheless, overall cell proliferation and total DNA were highest on the polished surface. Zirconia sintered at a lower temperature (1300 °C vs. 1450 °C) had open porosity and presented reduced proliferation as assessed by alamarBlue™ assay, possibly because the openness of the pores prevented cells developing a local microenvironment. All cells retained the typical polygonal morphology of osteoblast-like cells with variations attributable to the underlying surface notably alignment along the grooves of the abraded surface. - Highlights: • Biocompatibility of chemically identical, topologically different ZrO{sub 2} was tested. • ZrO{sub 2} promoted cell adhesion, proliferation, differentiation and nodule formation. • Proliferation was high on polished ZrO{sub 2} but initial recruitment was high on abraded ZrO{sub 2}. • With open porosity, proliferation was low; cells cannot establish a microenvironment.

  7. On switching response surface models, with applications to the structural health monitoring of bridges

    Science.gov (United States)

    Worden, K.; Cross, E. J.

    2018-01-01

    Structural Health Monitoring (SHM) is the engineering discipline of diagnosing damage and estimating safe remaining life for structures and systems. Often, SHM is accomplished by detecting changes in measured quantities from the structure of interest; if there are no competing explanations for the changes, one infers that they are the result of damage. If the structure of interest is subject to changes in its environmental or operational conditions, one must understand the effects of these changes in order that one does not falsely claim that damage has occurred when changes in measured quantities are observed. This problem - the problem of confounding influences - is particularly pressing for civil infrastructure where the given structure is usually openly exposed to the weather and may be subject to strongly varying operational conditions. One approach to understanding confounding influences is to construct a data-based response surface model that can represent measurement variations as a function of environmental and operational variables. The models can then be used to remove environmental and operational variations so that change detection algorithms signal the occurrence of damage alone. The current paper is concerned with such response surface models in the case of SHM of bridges. In particular, classes of response surface models that can switch discontinuously between regimes are discussed. Recently, it has been shown that Gaussian Process (GP) models are an effective means of developing response surface or surrogate models. However, the GP approach runs into difficulties if changes in the latent variables cause the structure of interest to abruptly switch between regimes. A good example here, which is well known in the SHM literature, is given by the Z24 Bridge in Switzerland which completely changed its dynamical behaviour when it cooled below zero degrees Celsius as the asphalt of the deck stiffened. The solution proposed here is to adopt the recently

  8. Responses of Surface Ozone Air Quality to Anthropogenic Nitrogen Deposition

    Science.gov (United States)

    Zhang, L.; Zhao, Y.; Tai, A. P. K.; Chen, Y.; Pan, Y.

    2017-12-01

    Human activities have substantially increased atmospheric deposition of reactive nitrogen to the Earth's surface, inducing unintentional effects on ecosystems with complex environmental and climate consequences. One consequence remaining unexplored is how surface air quality might respond to the enhanced nitrogen deposition through surface-atmosphere exchange. We combine a chemical transport model (GEOS-Chem) and a global land model (Community Land Model) to address this issue with a focus on ozone pollution in the Northern Hemisphere. We consider three processes that are important for surface ozone and can be perturbed by addition of atmospheric deposited nitrogen: emissions of biogenic volatile organic compounds (VOCs), ozone dry deposition, and soil nitrogen oxide (NOx) emissions. We find that present-day anthropogenic nitrogen deposition (65 Tg N a-1 to the land), through enhancing plant growth (represented as increases in vegetation leaf area index (LAI) in the model), could increase surface ozone from increased biogenic VOC emissions, but could also decrease ozone due to higher ozone dry deposition velocities. Meanwhile, deposited anthropogenic nitrogen to soil enhances soil NOx emissions. The overall effect on summer mean surface ozone concentrations show general increases over the globe (up to 1.5-2.3 ppbv over the western US and South Asia), except for some regions with high anthropogenic NOx emissions (0.5-1.0 ppbv decreases over the eastern US, Western Europe, and North China). We compare the surface ozone changes with those driven by the past 20-year climate and historical land use changes. We find that the impacts from anthropogenic nitrogen deposition can be comparable to the climate and land use driven surface ozone changes at regional scales, and partly offset the surface ozone reductions due to land use changes reported in previous studies. Our study emphasizes the complexity of biosphere-atmosphere interactions, which can have important

  9. Tuning the deposition of molecular graphene nanoribbons by surface functionalization

    Science.gov (United States)

    Konnerth, R.; Cervetti, C.; Narita, A.; Feng, X.; Müllen, K.; Hoyer, A.; Burghard, M.; Kern, K.; Dressel, M.; Bogani, L.

    2015-07-01

    We show that individual, isolated graphene nanoribbons, created with a molecular synthetic approach, can be assembled on functionalised wafer surfaces treated with silanes. The use of surface groups with different hydrophobicities allows tuning the density of the ribbons and assessing the products of the polymerisation process.

  10. Response of Korean pine's functional traits to geography and climate.

    Directory of Open Access Journals (Sweden)

    Yichen Dong

    Full Text Available This study analyzed the characteristics of Korean pine (Pinus koraiensis functional trait responses to geographic and climatic factors in the eastern region of Northeast China (41°-48°N and the linear relationships among Korean pine functional traits, to explore this species' adaptability and ecological regulation strategies under different environmental conditions. Korean pine samples were collected from eight sites located at different latitudes, and the following factors were determined for each site: geographic factors-latitude, longitude, and altitude; temperature factors-mean annual temperature (MAT, growth season mean temperature (GST, and mean temperature of the coldest month (MTCM; and moisture factors-annual precipitation (AP, growth season precipitation (GSP, and potential evapotranspiration (PET. The Korean pine functional traits examined were specific leaf area (SLA, leaf thickness (LT, leaf dry matter content (LDMC, specific root length (SRL, leaf nitrogen content (LNC, leaf phosphorus content (LPC, root nitrogen content (RNC, and root phosphorus content (RPC. The results showed that Korean pine functional traits were significantly correlated to latitude, altitude, GST, MTCM, AP, GSP, and PET. Among the Korean pine functional traits, SLA showed significant linear relationships with LT, LDMC, LNC, LPC, and RPC, and LT showed significant linear relationships with LDMC, SRL, LNC, LPC, RNC, and RPC; the linear relationships between LNC, LPC, RNC, and RPC were also significant. In conclusion, Korean pine functional trait responses to latitude resulted in its adaptation to geographic and climatic factors. The main limiting factors were precipitation and evapotranspiration, followed by altitude, latitude, GST, and MTCM. The impacts of longitude and MAT were not obvious. Changes in precipitation and temperature were most responsible for the close correlation among Korean pine functional traits, reflecting its adaption to habitat

  11. Experimental design and multiple response optimization. Using the desirability function in analytical methods development.

    Science.gov (United States)

    Candioti, Luciana Vera; De Zan, María M; Cámara, María S; Goicoechea, Héctor C

    2014-06-01

    A review about the application of response surface methodology (RSM) when several responses have to be simultaneously optimized in the field of analytical methods development is presented. Several critical issues like response transformation, multiple response optimization and modeling with least squares and artificial neural networks are discussed. Most recent analytical applications are presented in the context of analytLaboratorio de Control de Calidad de Medicamentos (LCCM), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, C.C. 242, S3000ZAA Santa Fe, ArgentinaLaboratorio de Control de Calidad de Medicamentos (LCCM), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, C.C. 242, S3000ZAA Santa Fe, Argentinaical methods development, especially in multiple response optimization procedures using the desirability function. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Osteoblast cell response to surface-modified carbon nanotubes

    International Nuclear Information System (INIS)

    Zhang Faming; Weidmann, Arne; Nebe, J. Barbara; Burkel, Eberhard

    2012-01-01

    In order to investigate the interaction of cells with modified multi-walled carbon nanotubes (MWCNTs) for their potential biomedical applications, the MWCNTs were chemically modified with carboxylic acid groups (–COOH), polyvinyl alcohol (PVA) polymer and biomimetic apatite on their surfaces. Additionally, human osteoblast MG-63 cells were cultured in the presence of the surface-modified MWCNTs. The metabolic activities of osteoblastic cells, cell proliferation properties, as well as cell morphology were studied. The surface modification of MWCNTs with biomimetic apatite exhibited a significant increase in the cell viability of osteoblasts, up to 67.23%. In the proliferation phases, there were many more cells in the biomimetic apatite-modified MWCNT samples than in the MWCNTs–COOH. There were no obvious changes in cell morphology in osteoblastic MG-63 cells cultured in the presence of these chemically-modified MWCNTs. The surface modification of MWCNTs with apatite achieves an effective enhancement of their biocompatibility.

  13. Surface Plasmon Polaritons on Silver Gratings for Optimal SERS Response.

    Czech Academy of Sciences Publication Activity Database

    Kalachyova, Y.; Mareš, D.; Lyutakov, O.; Koštejn, Martin; Lapčák, L.; Svorčík, V.

    2015-01-01

    Roč. 119, č. 17 (2015), s. 9506-9512 ISSN 1932-7447 Institutional support: RVO:67985858 Keywords : enhanced raman-scattering * metallic surface * relief gratings Subject RIV: CC - Organic Chemistry Impact factor: 4.509, year: 2015

  14. Pheochromocytoma (PC12 Cell Response on Mechanobactericidal Titanium Surfaces

    Directory of Open Access Journals (Sweden)

    Jason V. Wandiyanto

    2018-04-01

    Full Text Available Titanium is a biocompatible material that is frequently used for making implantable medical devices. Nanoengineering of the surface is the common method for increasing material biocompatibility, and while the nanostructured materials are well-known to represent attractive substrata for eukaryotic cells, very little information has been documented about the interaction between mammalian cells and bactericidal nanostructured surfaces. In this study, we investigated the effect of bactericidal titanium nanostructures on PC12 cell attachment and differentiation—a cell line which has become a widely used in vitro model to study neuronal differentiation. The effects of the nanostructures on the cells were then compared to effects observed when the cells were placed in contact with non-structured titanium. It was found that bactericidal nanostructured surfaces enhanced the attachment of neuron-like cells. In addition, the PC12 cells were able to differentiate on nanostructured surfaces, while the cells on non-structured surfaces were not able to do so. These promising results demonstrate the potential application of bactericidal nanostructured surfaces in biomedical applications such as cochlear and neuronal implants.

  15. Aging and response conflict solution: behavioural and functional connectivity changes.

    Science.gov (United States)

    Langner, Robert; Cieslik, Edna C; Behrwind, Simone D; Roski, Christian; Caspers, Svenja; Amunts, Katrin; Eickhoff, Simon B

    2015-01-01

    Healthy aging has been found associated with less efficient response conflict solution, but the cognitive and neural mechanisms have remained elusive. In a two-experiment study, we first examined the behavioural consequences of this putative age-related decline for conflicts induced by spatial stimulus-response incompatibility. We then used resting-state functional magnetic resonance imaging data from a large, independent sample of adults (n = 399; 18-85 years) to investigate age differences in functional connectivity between the nodes of a network previously found associated with incompatibility-induced response conflicts in the very same paradigm. As expected, overcoming interference from conflicting response tendencies took longer in older adults, even after accounting for potential mediator variables (general response speed and accuracy, motor speed, visuomotor coordination ability, and cognitive flexibility). Experiment 2 revealed selective age-related decreases in functional connectivity between bilateral anterior insula, pre-supplementary motor area, and right dorsolateral prefrontal cortex. Importantly, these age effects persisted after controlling for regional grey-matter atrophy assessed by voxel-based morphometry. Meta-analytic functional profiling using the BrainMap database showed these age-sensitive nodes to be more strongly linked to highly abstract cognition, as compared with the remaining network nodes, which were more strongly linked to action-related processing. These findings indicate changes in interregional coupling with age among task-relevant network nodes that are not specifically associated with conflict resolution per se. Rather, our behavioural and neural data jointly suggest that healthy aging is associated with difficulties in properly activating non-dominant but relevant task schemata necessary to exert efficient cognitive control over action.

  16. Development of the Parent Responses to School Functioning Questionnaire.

    Science.gov (United States)

    Barber Garcia, Brittany N; Gray, Laura S; Simons, Laura E; Logan, Deirdre E

    2017-10-01

    Parents play an important role in supporting school functioning in youth with chronic pain, but no validated tools exists to assess parental responses to child and adolescent pain behaviors in the school context. Such a tool would be useful in identifying targets of change to reduce pain-related school impairment. The goal of this study was to develop and preliminarily validate the Parent Responses to School Functioning Questionnaire (PRSF), a parent self-report measure of this construct. After initial expert review and pilot testing, the measure was administered to 418 parents of children (ages 6-17 years) seen for initial multidisciplinary chronic pain clinic evaluation. The final 16-item PRSF showed evidence of good internal consistency (α = .82) and 2-week test-retest reliability (intraclass correlation coefficient = .87). Criterion validity was demonstrated by significant correlations with school absence rates and overall school functioning, and construct validity was demonstrated by correlations with general parental responses to pain. Three subscales emerged capturing parents' personal distress, parents' level of distrust of the school, and parents' expectations and behaviors related to their child's management of challenging school situations. These results provide preliminary support for the PRSF as a psychometrically sound tool to assess parents' responses to child pain in the school setting. The 16-item PRSF measures parental responses to their child's chronic pain in the school context. The clinically useful measure can inform interventions aimed reducing functional disability in children with chronic pain by enhancing parents' ability to respond adaptively to child pain behaviors. Copyright © 2017 American Pain Society. Published by Elsevier Inc. All rights reserved.

  17. A Hybrid Density Functional Theory/Molecular Mechanics Approach for Linear Response Properties in Heterogeneous Environments.

    Science.gov (United States)

    Rinkevicius, Zilvinas; Li, Xin; Sandberg, Jaime A R; Mikkelsen, Kurt V; Ågren, Hans

    2014-03-11

    We introduce a density functional theory/molecular mechanical approach for computation of linear response properties of molecules in heterogeneous environments, such as metal surfaces or nanoparticles embedded in solvents. The heterogeneous embedding environment, consisting from metallic and nonmetallic parts, is described by combined force fields, where conventional force fields are used for the nonmetallic part and capacitance-polarization-based force fields are used for the metallic part. The presented approach enables studies of properties and spectra of systems embedded in or placed at arbitrary shaped metallic surfaces, clusters, or nanoparticles. The capability and performance of the proposed approach is illustrated by sample calculations of optical absorption spectra of thymidine absorbed on gold surfaces in an aqueous environment, where we study how different organizations of the gold surface and how the combined, nonadditive effect of the two environments is reflected in the optical absorption spectrum.

  18. Temperature-Responsive Anisotropic Slippery Surface for Smart Control of the Droplet Motion.

    Science.gov (United States)

    Wang, By Lili; Heng, Liping; Jiang, Lei

    2018-02-28

    Development of stimulus-responsive anisotropic slippery surfaces is important because of the high demand for such materials in the field of liquid directional-driven systems. However, current studies in the field of slippery surfaces are mainly conducted to prepare isotropic slippery surfaces. Although we have developed electric-responsive anisotropic slippery surfaces that enable smart control of the droplet motion, there remain challenges for designing temperature-responsive anisotropic slippery surfaces to control the liquid droplet motion on the surface and in the tube. In this work, temperature-responsive anisotropic slippery surfaces have been prepared by using paraffin, a thermo-responsive phase-transition material, as a lubricating fluid and directional porous polystyrene (PS) films as the substrate. The smart regulation of the droplet motion of several liquids on this surface was accomplished by tuning the substrate temperature. The uniqueness of this surface lies in the use of an anisotropic structure and temperature-responsive lubricating fluids to achieve temperature-driven smart control of the anisotropic motion of the droplets. Furthermore, this surface was used to design temperature-driven anisotropic microreactors and to manipulate liquid transfer in tubes. This work advances the understanding of the principles underlying anisotropic slippery surfaces and provides a promising material for applications in the biochip and microreactor system.

  19. Surface relief gratings: experiments, physical scenarios, and photoinduced (anomalous) dynamics of functionalized polymer chains

    Science.gov (United States)

    Mitus, A. C.; Radosz, W.; Wysoczanski, T.; Pawlik, G.

    2017-10-01

    Surface Relief Gratings (SRG) were demonstrated experimentally more than 20 years ago. Despite many years of research efforts the underlying physical mechanisms remain unclear. In this paper we present a short overview of the main concepts related to SRG - photofluidization and its counterpart, the orientational approach - based on a seminal paper by Saphiannikova et al. Next, we summarize the derivation of the cos2 θ potential, following the lines of recent paper of this group. Those results validate the generic Monte Carlo model for the photoinduced build-up of the density and SRG gratings in a model polymer matrix functionalized with azo-dyes, presented in another part of the paper. The characterization of the photoinduced motion of polymer chains, based on our recent paper, is briefly discussed in the last part of the paper. This discussion offers a sound insight into the mechanisms responsible for inscription of SRG as well as for single functionalized nanoparticle studies.

  20. Covalent organic polymer functionalization of activated carbon surfaces through acyl chloride for environmental clean-up

    DEFF Research Database (Denmark)

    Mines, Paul D.; Thirion, Damien; Uthuppu, Basil

    2017-01-01

    Nanoporous networks of covalent organic polymers (COPs) are successfully grafted on the surfaces of activated carbons, through a series of surface modification techniques, including acyl chloride formation by thionyl chloride. Hybrid composites of activated carbon functionalized with COPs exhibit...

  1. A microfluidic surface enhanced Raman spectroscopic biosensor using aptamer functionalized nanopillars

    DEFF Research Database (Denmark)

    Yang, J.; Palla, M.; Bosco, F. G.

    2013-01-01

    This paper presents a microchip incorporating an aptamer-functionalized nanopillar substrate, enabling the specific detection of low-abundance biomolecules using surface enhanced Raman spectroscopy (SERS). In a temperature controlled microchamber, aptamers immobilized on the nanostructure surface...

  2. Reliability-Based Stability Analysis of Rock Slopes Using Numerical Analysis and Response Surface Method

    Science.gov (United States)

    Dadashzadeh, N.; Duzgun, H. S. B.; Yesiloglu-Gultekin, N.

    2017-08-01

    While advanced numerical techniques in slope stability analysis are successfully used in deterministic studies, they have so far found limited use in probabilistic analyses due to their high computation cost. The first-order reliability method (FORM) is one of the most efficient probabilistic techniques to perform probabilistic stability analysis by considering the associated uncertainties in the analysis parameters. However, it is not possible to directly use FORM in numerical slope stability evaluations as it requires definition of a limit state performance function. In this study, an integrated methodology for probabilistic numerical modeling of rock slope stability is proposed. The methodology is based on response surface method, where FORM is used to develop an explicit performance function from the results of numerical simulations. The implementation of the proposed methodology is performed by considering a large potential rock wedge in Sumela Monastery, Turkey. The accuracy of the developed performance function to truly represent the limit state surface is evaluated by monitoring the slope behavior. The calculated probability of failure is compared with Monte Carlo simulation (MCS) method. The proposed methodology is found to be 72% more efficient than MCS, while the accuracy is decreased with an error of 24%.

  3. Ecosystem functional response across precipitation extremes in a sagebrush steppe.

    Science.gov (United States)

    Tredennick, Andrew T; Kleinhesselink, Andrew R; Taylor, J Bret; Adler, Peter B

    2018-01-01

    Precipitation is predicted to become more variable in the western United States, meaning years of above and below average precipitation will become more common. Periods of extreme precipitation are major drivers of interannual variability in ecosystem functioning in water limited communities, but how ecosystems respond to these extremes over the long-term may shift with precipitation means and variances. Long-term changes in ecosystem functional response could reflect compensatory changes in species composition or species reaching physiological thresholds at extreme precipitation levels. We conducted a five year precipitation manipulation experiment in a sagebrush steppe ecosystem in Idaho, United States. We used drought and irrigation treatments (approximately 50% decrease/increase) to investigate whether ecosystem functional response remains consistent under sustained high or low precipitation. We recorded data on aboveground net primary productivity (ANPP), species abundance, and soil moisture. We fit a generalized linear mixed effects model to determine if the relationship between ANPP and soil moisture differed among treatments. We used nonmetric multidimensional scaling to quantify community composition over the five years. Ecosystem functional response, defined as the relationship between soil moisture and ANPP, was similar among irrigation and control treatments, but the drought treatment had a greater slope than the control treatment. However, all estimates for the effect of soil moisture on ANPP overlapped zero, indicating the relationship is weak and uncertain regardless of treatment. There was also large spatial variation in ANPP within-years, which contributes to the uncertainty of the soil moisture effect. Plant community composition was remarkably stable over the course of the experiment and did not differ among treatments. Despite some evidence that ecosystem functional response became more sensitive under sustained drought conditions, the response

  4. Liquid crystal elastomer coatings with programmed response of surface profile

    NARCIS (Netherlands)

    Babakhanova, G.; Turiv, T.; Guo, Y.; Hendrikx, M.; Wei, Q.H.; Schenning, A.P.H.J.; Broer, D.J.; Lavrentovich, O.D.

    2018-01-01

    Stimuli-responsive liquid crystal elastomers with molecular orientation coupled to rubber-like elasticity show a great potential as elements in soft robotics, sensing, and transport systems. The orientational order defines their mechanical response to external stimuli, such as thermally activated

  5. Thermo-responsive cell culture carrier: Effects on macrophage functionality and detachment efficiency.

    Science.gov (United States)

    Rennert, Knut; Nitschke, Mirko; Wallert, Maria; Keune, Natalie; Raasch, Martin; Lorkowski, Stefan; Mosig, Alexander S

    2017-01-01

    Harvesting cultivated macrophages for tissue engineering purposes by enzymatic digestion of cell adhesion molecules can potentially result in unintended activation, altered function, or behavior of these cells. Thermo-responsive polymer is a promising tool that allows for gentle macrophage detachment without artificial activation prior to subculture within engineered tissue constructs. We therefore characterized different species of thermo-responsive polymers for their suitability as cell substrate and to mediate gentle macrophage detachment by temperature shift. Primary human monocyte- and THP-1-derived macrophages were cultured on thermo-responsive polymers and characterized for phagocytosis and cytokine secretion in response to lipopolysaccharide stimulation. We found that both cell types differentially respond in dependence of culture and stimulation on thermo-responsive polymers. In contrast to THP-1 macrophages, primary monocyte-derived macrophages showed no signs of impaired viability, artificial activation, or altered functionality due to culture on thermo-responsive polymers compared to conventional cell culture. Our study demonstrates that along with commercially available UpCell carriers, two other thermo-responsive polymers based on poly(vinyl methyl ether) blends are attractive candidates for differentiation and gentle detachment of primary monocyte-derived macrophages. In summary, we observed similar functionality and viability of primary monocyte-derived macrophages cultured on thermo-responsive polymers compared to standard cell culture surfaces. While this first generation of custom-made thermo-responsive polymers does not yet outperform standard culture approaches, our results are very promising and provide the basis for exploiting the unique advantages offered by custom-made thermo-responsive polymers to further improve macrophage culture and recovery in the future, including the covalent binding of signaling molecules and the reduction of

  6. Executing application function calls in response to an interrupt

    Science.gov (United States)

    Almasi, Gheorghe; Archer, Charles J.; Giampapa, Mark E.; Gooding, Thomas M.; Heidelberger, Philip; Parker, Jeffrey J.

    2010-05-11

    Executing application function calls in response to an interrupt including creating a thread; receiving an interrupt having an interrupt type; determining whether a value of a semaphore represents that interrupts are disabled; if the value of the semaphore represents that interrupts are not disabled: calling, by the thread, one or more preconfigured functions in dependence upon the interrupt type of the interrupt; yielding the thread; and if the value of the semaphore represents that interrupts are disabled: setting the value of the semaphore to represent to a kernel that interrupts are hard-disabled; and hard-disabling interrupts at the kernel.

  7. Overload protection: avoidance response to heavy plantar surface loading.

    Science.gov (United States)

    Robbins, S E; Hanna, A M; Gouw, G J

    1988-02-01

    Current footwear which are designed for use in running are examples of intentional biomechanical model integration into device design. The inadequacy of this footwear in protecting against injury is postulated to be due to fixation on inadequate models of locomotory biomechanics that do not provide for feedback control; in particular, an hypothesized plantar surface sensory-mediated feedback control system, which imparts overload protection during locomotion. A heuristic approach was used to identify the hypothesized system. A random series of loads (0 to 164 kg) was applied to the knee flexed at 90 degrees. In this testing system, plantar surface avoidance behavior was the difference between the sum of the leg weight and the load applied to the knee, and the load measured at the plantar surface; this was produced by activation of hip flexors. Significant avoidance behavior was found in all of the subjects (P less than 0.001). On all surfaces tested, including modern athletic footwear (P less than 0.001), its magnitude increased directly in relation to the load applied to the knee (P less than 0.001). There were significant differences in avoidance behavior in relation to the weight-bearing surfaces tested (P less than 0.05). With the identification of a feedback control system which would serve to moderate loading during locomotion, an explanation is provided as to why current athletic footwear do not protect and may be injurious; thus allowing the design of footwear which may be truly protective.

  8. Response of the global surface ozone distribution to Northern Hemisphere sea surface temperature changes: implications for long-range transport

    Science.gov (United States)

    Yi, Kan; Liu, Junfeng; Ban-Weiss, George; Zhang, Jiachen; Tao, Wei; Cheng, Yanli; Tao, Shu

    2017-07-01

    The response of surface ozone (O3) concentrations to basin-scale warming and cooling of Northern Hemisphere oceans is investigated using the Community Earth System Model (CESM). Idealized, spatially uniform sea surface temperature (SST) anomalies of ±1 °C are individually superimposed onto the North Pacific, North Atlantic, and North Indian oceans. Our simulations suggest large seasonal and regional variability in surface O3 in response to SST anomalies, especially in the boreal summer. The responses of surface O3 associated with basin-scale SST warming and cooling have similar magnitude but are opposite in sign. Increasing the SST by 1 °C in one of the oceans generally decreases the surface O3 concentrations from 1 to 5 ppbv. With fixed emissions, SST increases in a specific ocean basin in the Northern Hemisphere tend to increase the summertime surface O3 concentrations over upwind regions, accompanied by a widespread reduction over downwind continents. We implement the integrated process rate (IPR) analysis in CESM and find that meteorological O3 transport in response to SST changes is the key process causing surface O3 perturbations in most cases. During the boreal summer, basin-scale SST warming facilitates the vertical transport of O3 to the surface over upwind regions while significantly reducing the vertical transport over downwind continents. This process, as confirmed by tagged CO-like tracers, indicates a considerable suppression of intercontinental O3 transport due to increased tropospheric stability at lower midlatitudes induced by SST changes. Conversely, the responses of chemical O3 production to regional SST warming can exert positive effects on surface O3 levels over highly polluted continents, except South Asia, where intensified cloud loading in response to North Indian SST warming depresses both the surface air temperature and solar radiation, and thus photochemical O3 production. Our findings indicate a robust linkage between basin-scale SST

  9. Response of the global surface ozone distribution to Northern Hemisphere sea surface temperature changes: implications for long-range transport

    Directory of Open Access Journals (Sweden)

    K. Yi

    2017-07-01

    Full Text Available The response of surface ozone (O3 concentrations to basin-scale warming and cooling of Northern Hemisphere oceans is investigated using the Community Earth System Model (CESM. Idealized, spatially uniform sea surface temperature (SST anomalies of ±1 °C are individually superimposed onto the North Pacific, North Atlantic, and North Indian oceans. Our simulations suggest large seasonal and regional variability in surface O3 in response to SST anomalies, especially in the boreal summer. The responses of surface O3 associated with basin-scale SST warming and cooling have similar magnitude but are opposite in sign. Increasing the SST by 1 °C in one of the oceans generally decreases the surface O3 concentrations from 1 to 5 ppbv. With fixed emissions, SST increases in a specific ocean basin in the Northern Hemisphere tend to increase the summertime surface O3 concentrations over upwind regions, accompanied by a widespread reduction over downwind continents. We implement the integrated process rate (IPR analysis in CESM and find that meteorological O3 transport in response to SST changes is the key process causing surface O3 perturbations in most cases. During the boreal summer, basin-scale SST warming facilitates the vertical transport of O3 to the surface over upwind regions while significantly reducing the vertical transport over downwind continents. This process, as confirmed by tagged CO-like tracers, indicates a considerable suppression of intercontinental O3 transport due to increased tropospheric stability at lower midlatitudes induced by SST changes. Conversely, the responses of chemical O3 production to regional SST warming can exert positive effects on surface O3 levels over highly polluted continents, except South Asia, where intensified cloud loading in response to North Indian SST warming depresses both the surface air temperature and solar radiation, and thus photochemical O3 production. Our findings indicate a robust linkage

  10. DPP6 domains responsible for its localization and function.

    Science.gov (United States)

    Lin, Lin; Long, Laura K; Hatch, Michael M; Hoffman, Dax A

    2014-11-14

    Dipeptidyl peptidase-like protein 6 (DPP6) is an auxiliary subunit of the Kv4 family of voltage-gated K(+) channels known to enhance channel surface expression and potently accelerate their kinetics. DPP6 is a single transmembrane protein, which is structurally remarkable for its large extracellular domain. Included in this domain is a cysteine-rich motif, the function of which is unknown. Here we show that this cysteine-rich domain of DPP6 is required for its export from the ER and expression on the cell surface. Disulfide bridges formed at C349/C356 and C465/C468 of the cysteine-rich domain are necessary for the enhancement of Kv4.2 channel surface expression but not its interaction with Kv4.2 subunits. The short intracellular N-terminal and transmembrane domains of DPP6 associates with and accelerates the recovery from inactivation of Kv4.2, but the entire extracellular domain is necessary to enhance Kv4.2 surface expression and stabilization. Our findings show that the cysteine-rich domain of DPP6 plays an important role in protein folding of DPP6 that is required for transport of DPP6/Kv4.2 complexes out of the ER. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. Adsorption of surface functionalized silica nanoparticles onto mineral surfaces and decane/water interface

    International Nuclear Information System (INIS)

    Metin, Cigdem O.; Baran, Jimmie R.; Nguyen, Quoc P.

    2012-01-01

    The adsorption of silica nanoparticles onto representative mineral surfaces and at the decane/water interface was studied. The effects of particle size (the mean diameters from 5 to 75 nm), concentration and surface type on the adsorption were studied in detail. Silica nanoparticles with four different surfaces [unmodified, surface modified with anionic (sulfonate), cationic (quaternary ammonium (quat)) or nonionic (polyethylene glycol (PEG)) surfactant] were used. The zeta potential of these silica nanoparticles ranges from −79.8 to 15.3 mV. The shape of silica particles examined by a Hitachi-S5500 scanning transmission electron microscope (STEM) is quite spherical. The adsorption of all the nanoparticles (unmodified or surface modified) on quartz and calcite surfaces was found to be insignificant. We used interfacial tension (IFT) measurements to investigate the adsorption of silica nanoparticles at the decane/water interface. Unmodified nanoparticles or surface modified ones with sulfonate or quat do not significantly affect the IFT of the decane/water interface. It also does not appear that the particle size or concentration influences the IFT. However, the presence of PEG as a surface modifying material significantly reduces the IFT. The PEG surface modifier alone in an aqueous solution, without the nanoparticles, yields the same IFT reduction for an equivalent PEG concentration as that used for modifying the surface of nanoparticles. Contact angle measurements of a decane droplet on quartz or calcite plate immersed in water (or aqueous nanoparticle dispersion) showed a slight change in the contact angle in the presence of the studied nanoparticles. The results of contact angle measurements are in good agreement with experiments of adsorption of nanoparticles on mineral surfaces or decane/water interface. This study brings new insights into the understanding and modeling of the adsorption of surface-modified silica nanoparticles onto mineral surfaces and

  12. Thermo-responsive polymer-functionalized mesoporous carbon for controlled drug release

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Shenmin, E-mail: smzhu@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Chen Chenxin [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Chen Zhixin [Faculty of Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Liu Xinye; Li Yao; Shi Yang; Zhang Di [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2011-03-15

    Research highlights: {yields} A responsive drug delivery system based on poly(N-isopropyl acrylamide) (PNIPAM) functionalized ordered mesoporous carbon (CMK-3) is developed. {yields} A combination of surface modification of CMK-3 and in situ internal polymerization of PNIPAM was used. {yields} The system exhibited a pronounced transition at around 20-25 deg. C. - Abstract: A novel responsive drug delivery system based on poly(N-isopropyl acrylamide) (PNIPAM) functionalized ordered mesoporous carbon (CMK-3) is developed. The polymer-functionalized CMK-3 was obtained by a combination of simple surface modification of CMK-3 and in situ internal polymerization of PNIPAM. The formation of the PNIPAM inside the CMK-3 was confirmed by thermal gravimetric analysis, Fourier transform-infrared spectroscopy, scanning and transmission electron microscopy and N{sub 2} adsorption/desorption measurements. Controlled drug release tests through the porous network of the PNIPAM functionalized CMK-3 were carried out by measuring the uptake and release of ibuprofen in vitro. The release profiles exhibited a pronounced transition at around 20-25 deg. C. This thermo-sensitive release property of this delivery system was further confirmed by temperature-variable hydrogen nuclear magnetic resonance analysis. The internal PNIPAM layers acted as a storage gate as well as a release switch in response to the stimuli of environment.

  13. Photoelectric work function measurement of a cesiated metal surface and its correlation with the surface-produced H- ion flux

    International Nuclear Information System (INIS)

    Wada, M.; Berkner, K.H.; Pyle, R.V.; Stearns, J.W.

    1982-09-01

    For application in plasma heating, fueling, and current drive of magnetic fusion devices, high current negative deuterium ion sources for intense neutral beam injectors are being developed using efficient production of negative hydrogen isotope ions on low work function metal surfaces imbedded in hydrogen plasmas. In order to investigate the correlation between work function and negative hydrogen ion production, photoelectron emission from a cesiated metal surface, which is immersed in a hydrogen plasma with an electron density less than 5 x 10 10 /cc, was measured in the photon energy range of 1.3 to 4.1 eV. The work function determination was based on Fowler's analysis, and at the optimum coverage a work function of less than 1.5 eV was observed for a Cs-Cu surface. Measured values of work functions for different Cs coverages were compared to the negative hydrogen currents produced at the metal surface in the discharge; the surface production of negative hydrogen ion current is monotonically increasing with decreasing work function

  14. Interplay between grain structure and protein adsorption on functional response of osteoblasts: ultrafine-grained versus coarse-grained substrates.

    Science.gov (United States)

    Misra, R D K; Nune, C; Pesacreta, T C; Somani, M C; Karjalainen, L P

    2013-01-01

    The rapid adsorption of proteins is the starting and primary biological response that occurs when a biomedical device is implanted in the physiological system. The biological response, however, depends on the surface characteristics of the device. Considering the significant interest in nano-/ultrafine surfaces and nanostructured coatings, we describe here, the interplay between grain structure and protein adsorption (bovine serum albumin: BSA) on osteoblasts functions by comparing nanograined/ultrafine-grained (NG/UFG) and coarse-grained (CG: grain size in the micrometer range) substrates by investigating cell-substrate interactions. The protein adsorption on NG/UFG surface was beneficial in favorably modulating biological functions including cell attachment, proliferation, and viability, whereas the effect was less pronounced on protein adsorbed CG surface. Additionally, immunofluorescence studies demonstrated stronger vinculin signals associated with actin stress fibers in the outer regions of the cells and cellular extensions on protein adsorbed NG/UFG surface. The functional response followed the sequence: NG/UFG(BSA) > NG/UFG > CG(BSA) > CG. The differences in the cellular response on bare and protein adsorbed NG/UFG and CG surfaces are attributed to cumulative contribution of grain structure and degree of hydrophilicity. The study underscores the potential advantages of protein adsorption on artificial biomedical devices to enhance the bioactivity and regulate biological functions. Copyright © 2012 Wiley Periodicals, Inc.

  15. An optimization study on transesterification catalyzed by the activated carbide slag through the response surface methodology

    International Nuclear Information System (INIS)

    Liu, Mengqi; Niu, Shengli; Lu, Chunmei; Cheng, Shiqing

    2015-01-01

    Highlights: • New catalyst material for biodiesel production. • New utilization approach of waste carbide slag. • Detailed characterization of carbide slag used as transesterification catalyst. • Optimal parameters for biodiesel production obtained by response surface methodology. • Effect of impurities on catalytic activity of carbide slag in transesterification. - Abstract: After activated at 850 °C under air condition, calcium hydroxide and calcium carbonate in carbide slag are transformed into calcium oxide. The prepared transesterification catalyst, labeled as CS-850, gains surface area of 8.00 m 2 g −1 , functional groups of vanishing O−C−O and O−H bonds, surface morphology of tenuous branch and porous structure and basic strength of 9.8 < H – < 15.0. From aspects of the molar ratio of methanol to oil (γ), the catalyst added amount (ζ) and the reaction temperature (T r ), transesterification catalyzed by CS-850 is optimized through the Box–Behnken design of the response surface methodology (BBD–RSM). A quadratic polynomial model is preferred for transesterification efficiency prediction with coefficient of determination (R 2 ) of 0.9815. The optimal parameters are predicted to be γ = 13.8, ζ = 6.7% and T r = 60 °C with the efficiency of 94.70% and validated by experimental value of 93.83%. Meanwhile, γ is demonstrated to be the most significant variable for the minimum p-value. Besides, CS-850 performs acceptable reusability and for the fifth time reusage, efficiency of 82.61% could still be supplied. Aluminium oxide is proved to have the greatest effect on the catalytic activity of CS-850 among other small quality oxides. Physicochemical properties of the purified biodiesel meet American Society for Testing and Material (ASTM) standard

  16. Response function of spin-isospin nuclear excitations

    International Nuclear Information System (INIS)

    Salvetti, A.R.

    1986-01-01

    The selected aspects of spin-isospir nuclear excitations are studied. The spreading width of M/ states in even Ca isotopes for the purpose of trying to understand the missing strenght specially in 44 Ca, was estimated. The doorway calculation, was used, considering the level of complexity next to the independent particle M/ state. Using a nuclear matter context, the system response function to a spin-isospin probe and verify how the response function behaves for free fermions and in the ring approximation was studied. Higher correlations to polarization propagation such as the induced interaction and self-energy corrections was introduced. The dopping of colletive effects by such collisions terms was verified. It was investigate how to estimate the short range term of the effective interaction in the spin-isospin channel and the possibility of detecting a difference between these short range terms in the longitudinal and the transverse channel, for understanding the absence of pior condensation precursor states and negative results in a recent attempt to detect differences between longitudinal and transverse response functions one naively expects theoretically. (author) [pt

  17. Convergence in the temperature response of leaf respiration across biomes and plant functional types.

    Science.gov (United States)

    Heskel, Mary A; O'Sullivan, Odhran S; Reich, Peter B; Tjoelker, Mark G; Weerasinghe, Lasantha K; Penillard, Aurore; Egerton, John J G; Creek, Danielle; Bloomfield, Keith J; Xiang, Jen; Sinca, Felipe; Stangl, Zsofia R; Martinez-de la Torre, Alberto; Griffin, Kevin L; Huntingford, Chris; Hurry, Vaughan; Meir, Patrick; Turnbull, Matthew H; Atkin, Owen K

    2016-04-05

    Plant respiration constitutes a massive carbon flux to the atmosphere, and a major control on the evolution of the global carbon cycle. It therefore has the potential to modulate levels of climate change due to the human burning of fossil fuels. Neither current physiological nor terrestrial biosphere models adequately describe its short-term temperature response, and even minor differences in the shape of the response curve can significantly impact estimates of ecosystem carbon release and/or storage. Given this, it is critical to establish whether there are predictable patterns in the shape of the respiration-temperature response curve, and thus in the intrinsic temperature sensitivity of respiration across the globe. Analyzing measurements in a comprehensive database for 231 species spanning 7 biomes, we demonstrate that temperature-dependent increases in leaf respiration do not follow a commonly used exponential function. Instead, we find a decelerating function as leaves warm, reflecting a declining sensitivity to higher temperatures that is remarkably uniform across all biomes and plant functional types. Such convergence in the temperature sensitivity of leaf respiration suggests that there are universally applicable controls on the temperature response of plant energy metabolism, such that a single new function can predict the temperature dependence of leaf respiration for global vegetation. This simple function enables straightforward description of plant respiration in the land-surface components of coupled earth system models. Our cross-biome analyses shows significant implications for such fluxes in cold climates, generally projecting lower values compared with previous estimates.

  18. Optimal hemodynamic response model for functional near-infrared spectroscopy.

    Science.gov (United States)

    Kamran, Muhammad A; Jeong, Myung Yung; Mannan, Malik M N

    2015-01-01

    Functional near-infrared spectroscopy (fNIRS) is an emerging non-invasive brain imaging technique and measures brain activities by means of near-infrared light of 650-950 nm wavelengths. The cortical hemodynamic response (HR) differs in attributes at different brain regions and on repetition of trials, even if the experimental paradigm is kept exactly the same. Therefore, an HR model that can estimate such variations in the response is the objective of this research. The canonical hemodynamic response function (cHRF) is modeled by two Gamma functions with six unknown parameters (four of them to model the shape and other two to scale and baseline respectively). The HRF model is supposed to be a linear combination of HRF, baseline, and physiological noises (amplitudes and frequencies of physiological noises are supposed to be unknown). An objective function is developed as a square of the residuals with constraints on 12 free parameters. The formulated problem is solved by using an iterative optimization algorithm to estimate the unknown parameters in the model. Inter-subject variations in HRF and physiological noises have been estimated for better cortical functional maps. The accuracy of the algorithm has been verified using 10 real and 15 simulated data sets. Ten healthy subjects participated in the experiment and their HRF for finger-tapping tasks have been estimated and analyzed. The statistical significance of the estimated activity strength parameters has been verified by employing statistical analysis (i.e., t-value > t critical and p-value < 0.05).

  19. Atomic Resolution Imaging and Quantification of Chemical Functionality of Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Udo D. [Yale Univ., New Haven, CT (United States). Dept. of Mechanical Engineering and Materials Science; Altman, Eric I. [Yale Univ., New Haven, CT (United States). Dept. of Chemical and Environmental Engineering

    2014-12-10

    The work carried out from 2006-2014 under DoE support was targeted at developing new approaches to the atomic-scale characterization of surfaces that include species-selective imaging and an ability to quantify chemical surface interactions with site-specific accuracy. The newly established methods were subsequently applied to gain insight into the local chemical interactions that govern the catalytic properties of model catalysts of interest to DoE. The foundation of our work was the development of three-dimensional atomic force microscopy (3DAFM), a new measurement mode that allows the mapping of the complete surface force and energy fields with picometer resolution in space (x, y, and z) and piconewton/millielectron volts in force/energy. From this experimental platform, we further expanded by adding the simultaneous recording of tunneling current (3D-AFM/STM) using chemically well-defined tips. Through comparison with simulations, we were able to achieve precise quantification and assignment of local chemical interactions to exact positions within the lattice. During the course of the project, the novel techniques were applied to surface-oxidized copper, titanium dioxide, and silicon oxide. On these materials, defect-induced changes to the chemical surface reactivity and electronic charge density were characterized with site-specific accuracy.

  20. Improved adhesion of Ag NPs to the polyethylene terephthalate surface via atmospheric plasma treatment and surface functionalization

    Science.gov (United States)

    Shen, Tao; Liu, Yong; Zhu, Yan; Yang, De-Quan; Sacher, Edward

    2017-07-01

    Ag nanoparticles (NPs) have been widely applied, as important antibacterial materials, on textile and polymer surfaces. However, their adhesion to nonreactive polymer surfaces is generally too weak for many applications. Here, we propose a two-step process, atmospheric plasma treatment followed by a surface chemical modification process, which enhances their adhesion to polyethylene terephthalate (PET) surfaces. We found that, compared to either plasma treatments or surface chemical functionalizations, alone, this combination greatly enhanced their adhesion. The plasma treatment resulted in an increase of active sites (sbnd OH, sbnd CHdbnd O and COOH) at the PET surface, permitting increased bonding to 3-aminopropyltriethoxysilane (APTES), whose sbnd NH2 groups were then able to form a bonding complex with the Ag NPs.

  1. Evaluation of optical functional surfaces on the injection moulding insert by micro milling process

    DEFF Research Database (Denmark)

    Li, Dongya; Davoudinejad, Ali; Zhang, Yang

    2017-01-01

    This study presents the optimization of micro milling process for manufacturing injection moulding inserts with an optical functionalsurface. The objective is the optimal surface functionality. Micro ridges were used as the microstructures to realize the function to generate contrast between...

  2. Application of response surface methodology for determining cutting ...

    Indian Academy of Sciences (India)

    The results indicate that the depth of cut is the dominant factor affecting cutting ... between forces and cutting regime could be represented by power function type ..... CNEPRU Research Project, CODE : 0301520090008 (University of Guelma).

  3. Vitamin D, surface electromyography and physical function in uraemic patients

    DEFF Research Database (Denmark)

    Heaf, J.G.; Mølsted, Stig; Harrison, Adrian Paul

    2010-01-01

    EMG signal peak-peak amplitude, frequency and RMS were positively correlated to the quality of life scales Physical Function, Role Physical, General Health, Vitality, Social Function, Mental Health, and Physical Component Scale (p ... was to investigate the association between 25-OHD and muscle function as well as physical function in chronic kidney disease (CKD) and peritoneal dialysis (PD) patients. Methods: In this cross-sectional study, 21 adult patients with CKD stage 3-5 and 21 patients treated with PD were included. Standard biochemistry......) under voluntary contractions. Physical function was determined using a 30-second Chair Stand Test and the Short Form 36 quality of life questionnaire. Clinical characteristics were collected from the patient records. Results: Moderate vitamin 25-OHD deficiency (

  4. A note on monotonicity of item response functions for ordered polytomous item response theory models.

    Science.gov (United States)

    Kang, Hyeon-Ah; Su, Ya-Hui; Chang, Hua-Hua

    2018-03-08

    A monotone relationship between a true score (τ) and a latent trait level (θ) has been a key assumption for many psychometric applications. The monotonicity property in dichotomous response models is evident as a result of a transformation via a test characteristic curve. Monotonicity in polytomous models, in contrast, is not immediately obvious because item response functions are determined by a set of response category curves, which are conceivably non-monotonic in θ. The purpose of the present note is to demonstrate strict monotonicity in ordered polytomous item response models. Five models that are widely used in operational assessments are considered for proof: the generalized partial credit model (Muraki, 1992, Applied Psychological Measurement, 16, 159), the nominal model (Bock, 1972, Psychometrika, 37, 29), the partial credit model (Masters, 1982, Psychometrika, 47, 147), the rating scale model (Andrich, 1978, Psychometrika, 43, 561), and the graded response model (Samejima, 1972, A general model for free-response data (Psychometric Monograph no. 18). Psychometric Society, Richmond). The study asserts that the item response functions in these models strictly increase in θ and thus there exists strict monotonicity between τ and θ under certain specified conditions. This conclusion validates the practice of customarily using τ in place of θ in applied settings and provides theoretical grounds for one-to-one transformations between the two scales. © 2018 The British Psychological Society.

  5. Temperature response functions (G-functions) for single pile heat exchangers

    International Nuclear Information System (INIS)

    Loveridge, Fleur; Powrie, William

    2013-01-01

    Foundation piles used as heat exchangers as part of a ground energy system have the potential to reduce energy use and carbon dioxide emissions from new buildings. However, current design approaches for pile heat exchangers are based on methods developed for boreholes which have a different geometry, with a much larger aspect (length to diameter) ratio. Current methods also neglect the transient behaviour of the pile concrete, instead assuming a steady state resistance for design purposes. As piles have a much larger volume of concrete than boreholes, this neglects the significant potential for heat storage within the pile. To overcome these shortcomings this paper presents new pile temperature response functions (G-functions) which are designed to reflect typical geometries of pile heat exchangers and include the transient response of the pile concrete. Owing to the larger number of pile sizes and pipe configurations which are possible with pile heat exchangers it is not feasible to developed a single unified G-function and instead upper and lower bound solutions are provided for different aspects ratios. - Highlights: • We present new temperature response functions for pile heat exchangers. • The functions include transient heat transfer within the pile concrete. • Application of the functions reduces the resulting calculated temperature ranges. • Greater energy efficiency is possible by accounting for heat storage in the pile

  6. Finite element modelling of Plantar Fascia response during running on different surface types

    Science.gov (United States)

    Razak, A. H. A.; Basaruddin, K. S.; Salleh, A. F.; Rusli, W. M. R.; Hashim, M. S. M.; Daud, R.

    2017-10-01

    Plantar fascia is a ligament found in human foot structure located beneath the skin of human foot that functioning to stabilize longitudinal arch of human foot during standing and normal gait. To perform direct experiment on plantar fascia seems very difficult since the structure located underneath the soft tissue. The aim of this study is to develop a finite element (FE) model of foot with plantar fascia and investigate the effect of the surface hardness on biomechanical response of plantar fascia during running. The plantar fascia model was developed using Solidworks 2015 according to the bone structure of foot model that was obtained from Turbosquid database. Boundary conditions were set out based on the data obtained from experiment of ground reaction force response during running on different surface hardness. The finite element analysis was performed using Ansys 14. The results found that the peak of stress and strain distribution were occur on the insertion of plantar fascia to bone especially on calcaneal area. Plantar fascia became stiffer with increment of Young’s modulus value and was able to resist more loads. Strain of plantar fascia was decreased when Young’s modulus increased with the same amount of loading.

  7. Density functional theory in surface chemistry and catalysis

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet; Abild-Pedersen, Frank; Studt, Felix

    2011-01-01

    Recent advances in the understanding of reactivity trends for chemistry at transition-metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. The current status of the field is discussed with an emphasis on the role of coupling theory and experiment and future...

  8. Improving Joint Function Using Photochemical Hydrogels for Articular Surface Repair

    Science.gov (United States)

    2017-02-01

    cartilage surface. Not only does this repair require multiple surgeries to complete, but there is little data supporting the benefits of ACI versus...Is it possible to reduce the knee joint compression force during level walking with hiking poles? Scand J Med Sci Sports 2011;21:e195–e200. 1338

  9. Symposium Supramolecular Assemblies on Surface: Nanopatterning, Functionality and Reactivity

    Science.gov (United States)

    2016-05-19

    formed and we relate these observations to recent reports of de- wetting of C60 on alkali halide surfaces. The hBN flakes, which are prepared by... annealing will be discussed while for dicarbonitrile polyphenyl derivatives the adsorption behavior on Au(111) will be compared to the one on graphene

  10. Superparamagnetic bead interactions with functionalized surfaces characterized by an immunomicroarray

    DEFF Research Database (Denmark)

    Skottrup, Peter Durand; Hansen, Mikkel Fougt; Moresco, Jacob Lange

    2010-01-01

    optimized Polyethylene glycol-based surfaces with different end groups on the anchor molecule, 2,4,6-trichloro-1,3,5-triazine (TsT), were synthesized and compared with the standard (3-aminopropyl)triethoxysilane (APTS)/glutaraldehyde chemistry APTS/glutaraldehyde, directly linked TsT and bare H2O2-activated...

  11. Frequency Selective Surfaces for extended Bandwidth backing reflector functions

    NARCIS (Netherlands)

    Pasian, M.; Neto, A.; Monni, S.; Ettorre, M.; Gerini, G.

    2008-01-01

    This paper deals with the use of Frequency Selective Surfaces (FSS) to increase the Efficiency × Bandwidth product in Ultra-Wide Band (UWB) antenna arrays whose efficiency is limited by the front-to-back ratio. If the backing reflector is realized in one metal plane solution its location will be

  12. Surface functionalization of HF-treated silicon nanowires

    Indian Academy of Sciences (India)

    Administrator

    place when silicon nanowires reacted with 2,2,2-trifluoroethyl acrylate, and reductive deposition reaction occurred in the ... detection of fM level of protein. 14 and DNA. 15 ... surfaces can be easily modified to act as both elec- tron-transfer ...

  13. Functionalization of silicon nanowire surfaces with metal-organic frameworks

    KAUST Repository

    Liu, Nian; Yao, Yan; Cha, Judy; McDowell, Matthew T.; Han, Yu; Cui, Yi

    2011-01-01

    -dimensional electronic properties. Integration of the two materials into one composite could synergistically combine the advantages of both materials and lead to new applications. We report the first example of a MOF synthesized on surface-modified SiNWs. The synthesis

  14. Surface effects on the electroelastic responses of a thin piezoelectric plate with nanoscale thickness

    International Nuclear Information System (INIS)

    Yan Zhi; Jiang Liying

    2012-01-01

    This work aims to investigate the electroelastic responses of a thin piezoelectric plate under mechanical and electrical loads with the consideration of surface effects. Surface effects, including surface elasticity, residual surface stress and surface piezoelectricity, are incorporated into the conventional Kirchhoff plate theory for a piezoelectric plate via the surface piezoelectricity model and the generalized Young-Laplace equations. Different from the results predicted by the conventional plate theory ignoring the surface effects, the proposed model predicts size-dependent behaviours of the piezoelectric thin plate with nanoscale thickness. It is found that surface effects have significant influence on the electroelastic responses of the piezoelectric nanoplate. This work is expected to provide more accurate predictions on characterizing nanofilm or nanoribbon based piezoelectric devices in nanoelectromechanical systems. (paper)

  15. Surface characterization and cytotoxicity response of biodegradable magnesium alloys

    International Nuclear Information System (INIS)

    Pompa, Luis; Rahman, Zia Ur; Munoz, Edgar; Haider, Waseem

    2015-01-01

    Magnesium alloys have raised an immense amount of interest to many researchers because of their evolution as a new kind of third generation materials. Due to their biocompatibility, density, and mechanical properties, magnesium alloys are frequently reported as prospective biodegradable implant materials. Moreover, magnesium alloys experience a natural phenomenon to biodegrade in aqueous solutions due to its corrosion activity, which is excellent for orthopedic and cardiovascular applications. However, a major concern with such alloys is fast and non-uniform corrosion degradation. Controlling the degradation rate in the physiological environment determines the success of biodegradable implants. In this investigation, three different grades of magnesium alloys: AZ31B, AZ91E and ZK60A were studied for their corrosion resistance and biocompatibility. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and contact angle meter are used to study surface morphology, chemistry, roughness and wettability, respectively. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium based bio-assay, MTS. - Highlights: • Micro-textured features formed after the anodization of magnesium alloys. • Contact angle increased and surface free energy decreased by anodization. • Corrosion rate increased for anodized surfaces compared to untreated samples. • Cell viability was greater than 75% implying the cytocompatibility of Mg alloys

  16. Surface characterization and cytotoxicity response of biodegradable magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pompa, Luis; Rahman, Zia Ur; Munoz, Edgar; Haider, Waseem, E-mail: haiderw@utpa.edu

    2015-04-01

    Magnesium alloys have raised an immense amount of interest to many researchers because of their evolution as a new kind of third generation materials. Due to their biocompatibility, density, and mechanical properties, magnesium alloys are frequently reported as prospective biodegradable implant materials. Moreover, magnesium alloys experience a natural phenomenon to biodegrade in aqueous solutions due to its corrosion activity, which is excellent for orthopedic and cardiovascular applications. However, a major concern with such alloys is fast and non-uniform corrosion degradation. Controlling the degradation rate in the physiological environment determines the success of biodegradable implants. In this investigation, three different grades of magnesium alloys: AZ31B, AZ91E and ZK60A were studied for their corrosion resistance and biocompatibility. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and contact angle meter are used to study surface morphology, chemistry, roughness and wettability, respectively. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium based bio-assay, MTS. - Highlights: • Micro-textured features formed after the anodization of magnesium alloys. • Contact angle increased and surface free energy decreased by anodization. • Corrosion rate increased for anodized surfaces compared to untreated samples. • Cell viability was greater than 75% implying the cytocompatibility of Mg alloys.

  17. Bio-Inspired Functional Surfaces Based on Laser-Induced Periodic Surface Structures.

    Science.gov (United States)

    Müller, Frank A; Kunz, Clemens; Gräf, Stephan

    2016-06-15

    Nature developed numerous solutions to solve various technical problems related to material surfaces by combining the physico-chemical properties of a material with periodically aligned micro/nanostructures in a sophisticated manner. The utilization of ultra-short pulsed lasers allows mimicking numerous of these features by generating laser-induced periodic surface structures (LIPSS). In this review paper, we describe the physical background of LIPSS generation as well as the physical principles of surface related phenomena like wettability, reflectivity, and friction. Then we introduce several biological examples including e.g., lotus leafs, springtails, dessert beetles, moth eyes, butterfly wings, weevils, sharks, pangolins, and snakes to illustrate how nature solves technical problems, and we give a comprehensive overview of recent achievements related to the utilization of LIPSS to generate superhydrophobic, anti-reflective, colored, and drag resistant surfaces. Finally, we conclude with some future developments and perspectives related to forthcoming applications of LIPSS-based surfaces.

  18. Bio-Inspired Functional Surfaces Based on Laser-Induced Periodic Surface Structures

    Directory of Open Access Journals (Sweden)

    Frank A. Müller

    2016-06-01

    Full Text Available Nature developed numerous solutions to solve various technical problems related to material surfaces by combining the physico-chemical properties of a material with periodically aligned micro/nanostructures in a sophisticated manner. The utilization of ultra-short pulsed lasers allows mimicking numerous of these features by generating laser-induced periodic surface structures (LIPSS. In this review paper, we describe the physical background of LIPSS generation as well as the physical principles of surface related phenomena like wettability, reflectivity, and friction. Then we introduce several biological examples including e.g., lotus leafs, springtails, dessert beetles, moth eyes, butterfly wings, weevils, sharks, pangolins, and snakes to illustrate how nature solves technical problems, and we give a comprehensive overview of recent achievements related to the utilization of LIPSS to generate superhydrophobic, anti-reflective, colored, and drag resistant surfaces. Finally, we conclude with some future developments and perspectives related to forthcoming applications of LIPSS-based surfaces.

  19. Surface Mining and Reclamation Effects on Flood Response of Watersheds in the Central Appalachian Plateau Region

    Science.gov (United States)

    Ferrari, J. R.; Lookingbill, T. R.; McCormick, B.; Townsend, P. A.; Eshleman, K. N.

    2009-01-01

    Surface mining of coal and subsequent reclamation represent the dominant land use change in the central Appalachian Plateau (CAP) region of the United States. Hydrologic impacts of surface mining have been studied at the plot scale, but effects at broader scales have not been explored adequately. Broad-scale classification of reclaimed sites is difficult because standing vegetation makes them nearly indistinguishable from alternate land uses. We used a land cover data set that accurately maps surface mines for a 187-km2 watershed within the CAP. These land cover data, as well as plot-level data from within the watershed, are used with HSPF (Hydrologic Simulation Program-Fortran) to estimate changes in flood response as a function of increased mining. Results show that the rate at which flood magnitude increases due to increased mining is linear, with greater rates observed for less frequent return intervals. These findings indicate that mine reclamation leaves the landscape in a condition more similar to urban areas rather than does simple deforestation, and call into question the effectiveness of reclamation in terms of returning mined areas to the hydrological state that existed before mining.

  20. Response Surface Optimized Extraction of Total Triterpene Acids ...

    African Journals Online (AJOL)

    Purpose: To optimize extraction of total triterpene acids from loquat leaf and evaluate their in vitro antioxidant activities. Methods: The independent variables were ethanol concentration, extraction time, and solvent ratio, while the dependent variable was content of total triterpene acids. Composite design and response ...

  1. Optical response of a flat metallic surface coated with a monolayer array of latex spheres

    International Nuclear Information System (INIS)

    Shi Lei; Liu Xiaohan; Yin Haiwei; Zi Jian

    2010-01-01

    We report on the fabrication, characterization and simulation of a structure consisting of a flat metallic surface coated with a monolayer array of latex spheres. This structure shows interesting optical response: over flat metallic surfaces a series of reflection minima appear in reflection spectra. Numerical simulations revealed that the structure can support two types of surface modes: surface plasmon-polaritons bound at the metallic surface and guided modes confined to the array of latex spheres, or their hybrids. Both experimental and theoretical results indicated that these surface modes show well-defined band structures due to the introduced periodicity by the monolayer array of latex spheres.

  2. Work function and surface stability of tungsten-based thermionic electron emission cathodes

    Science.gov (United States)

    Jacobs, Ryan; Morgan, Dane; Booske, John

    2017-11-01

    Materials that exhibit a low work function and therefore easily emit electrons into vacuum form the basis of electronic devices used in applications ranging from satellite communications to thermionic energy conversion. W-Ba-O is the canonical materials system that functions as the thermionic electron emitter commercially used in a range of high-power electron devices. However, the work functions, surface stability, and kinetic characteristics of a polycrystalline W emitter surface are still not well understood or characterized. In this study, we examined the work function and surface stability of the eight lowest index surfaces of the W-Ba-O system using density functional theory methods. We found that under the typical thermionic cathode operating conditions of high temperature and low oxygen partial pressure, the most stable surface adsorbates are Ba-O species with compositions in the range of Ba0.125O-Ba0.25O per surface W atom, with O passivating all dangling W bonds and Ba creating work function-lowering surface dipoles. Wulff construction analysis reveals that the presence of O and Ba significantly alters the surface energetics and changes the proportions of surface facets present under equilibrium conditions. Analysis of previously published data on W sintering kinetics suggests that fine W particles in the size range of 100-500 nm may be at or near equilibrium during cathode synthesis and thus may exhibit surface orientation fractions well described by the calculated Wulff construction.

  3. How linear features alter predator movement and the functional response.

    KAUST Repository

    McKenzie, Hannah W

    2012-01-18

    In areas of oil and gas exploration, seismic lines have been reported to alter the movement patterns of wolves (Canis lupus). We developed a mechanistic first passage time model, based on an anisotropic elliptic partial differential equation, and used this to explore how wolf movement responses to seismic lines influence the encounter rate of the wolves with their prey. The model was parametrized using 5 min GPS location data. These data showed that wolves travelled faster on seismic lines and had a higher probability of staying on a seismic line once they were on it. We simulated wolf movement on a range of seismic line densities and drew implications for the rate of predator-prey interactions as described by the functional response. The functional response exhibited a more than linear increase with respect to prey density (type III) as well as interactions with seismic line density. Encounter rates were significantly higher in landscapes with high seismic line density and were most pronounced at low prey densities. This suggests that prey at low population densities are at higher risk in environments with a high seismic line density unless they learn to avoid them.

  4. How linear features alter predator movement and the functional response.

    KAUST Repository

    McKenzie, Hannah W; Merrill, Evelyn H; Spiteri, Raymond J; Lewis, Mark A

    2012-01-01

    In areas of oil and gas exploration, seismic lines have been reported to alter the movement patterns of wolves (Canis lupus). We developed a mechanistic first passage time model, based on an anisotropic elliptic partial differential equation, and used this to explore how wolf movement responses to seismic lines influence the encounter rate of the wolves with their prey. The model was parametrized using 5 min GPS location data. These data showed that wolves travelled faster on seismic lines and had a higher probability of staying on a seismic line once they were on it. We simulated wolf movement on a range of seismic line densities and drew implications for the rate of predator-prey interactions as described by the functional response. The functional response exhibited a more than linear increase with respect to prey density (type III) as well as interactions with seismic line density. Encounter rates were significantly higher in landscapes with high seismic line density and were most pronounced at low prey densities. This suggests that prey at low population densities are at higher risk in environments with a high seismic line density unless they learn to avoid them.

  5. Functional Associations by Response Overlap (FARO), a functional genomics approach matching gene expression phenotypes

    DEFF Research Database (Denmark)

    Nielsen, Henrik Bjørn; Mundy, J.; Willenbrock, Hanni

    2007-01-01

    The systematic comparison of transcriptional responses of organisms is a powerful tool in functional genomics. For example, mutants may be characterized by comparing their transcript profiles to those obtained in other experiments querying the effects on gene expression of many experimental facto...

  6. Inverse modelling of Köhler theory – Part 1: A response surface analysis of CCN spectra with respect to surface-active organic species

    Directory of Open Access Journals (Sweden)

    S. Lowe

    2016-09-01

    Full Text Available In this study a novel framework for inverse modelling of cloud condensation nuclei (CCN spectra is developed using Köhler theory. The framework is established by using model-generated synthetic measurements as calibration data for a parametric sensitivity analysis. Assessment of the relative importance of aerosol physicochemical parameters, while accounting for bulk–surface partitioning of surface-active organic species, is carried out over a range of atmospherically relevant supersaturations. By introducing an objective function that provides a scalar metric for diagnosing the deviation of modelled CCN concentrations from synthetic observations, objective function response surfaces are presented as a function of model input parameters. Crucially, for the chosen calibration data, aerosol–CCN spectrum closure is confirmed as a well-posed inverse modelling exercise for a subset of the parameters explored herein. The response surface analysis indicates that the appointment of appropriate calibration data is particularly important. To perform an inverse aerosol–CCN closure analysis and constrain parametric uncertainties, it is shown that a high-resolution CCN spectrum definition of the calibration data is required where single-valued definitions may be expected to fail. Using Köhler theory to model CCN concentrations requires knowledge of many physicochemical parameters, some of which are difficult to measure in situ on the scale of interest and introduce a considerable amount of parametric uncertainty to model predictions. For all partitioning schemes and environments modelled, model output showed significant sensitivity to perturbations in aerosol log-normal parameters describing the accumulation mode, surface tension, organic : inorganic mass ratio, insoluble fraction, and solution ideality. Many response surfaces pertaining to these parameters contain well-defined minima and are therefore good candidates for calibration using a Monte

  7. Response surface method applied to the thermoeconomic optimization of a complex cogeneration system modeled in a process simulator

    International Nuclear Information System (INIS)

    Pires, Thiago S.; Cruz, Manuel E.; Colaço, Marcelo J.

    2013-01-01

    This work presents the application of a surrogate model – a response surface – to replace the objective function to be minimized in the thermoeconomic optimization of a complex thermal system modeled with the aid of an expert process simulator. The objective function accounts for fuel, capital, operation and maintenance costs of the thermal system, and depends on nine decision variables. The minimization task is performed through the computational integration of two professional programs, a process simulator and a mathematical platform. Five algorithms are used to perform the optimization: the pattern search and genetic algorithms, both available in the mathematical platform, plus three custom-coded algorithms, differential evolution, particle swarm and simulated annealing. A comparative analysis of the performance of all five methods is presented, together with a critical appraisal of the surrogate model effectiveness. In the course of the optimization procedure, the process simulator computes the thermodynamic properties of all flows of the thermal system and solves the mass and energy balances each time the objective function has to be evaluated. By handling a set of radial basis functions as an approximation model to the original computationally expensive objective function, it is found here that the number of function evaluations can be appreciably reduced without significant deviation of the optimal value. The present study indicates that, for a thermoeconomic system optimization problem with a large number of decision variables and/or a costly objective function, the application of the response surface surrogate may prove more efficient than the original simulation model, reducing substantially the computational time involved in the optimization. - Highlights: ► A successful response surface method was proposed. ► The surrogate model may be more efficient than the original simulation model. ► Relative differences of less than 5% were found for the

  8. Graphs on Surfaces and the Partition Function of String Theory

    OpenAIRE

    Garcia-Islas, J. Manuel

    2007-01-01

    Graphs on surfaces is an active topic of pure mathematics belonging to graph theory. It has also been applied to physics and relates discrete and continuous mathematics. In this paper we present a formal mathematical description of the relation between graph theory and the mathematical physics of discrete string theory. In this description we present problems of the combinatorial world of real importance for graph theorists. The mathematical details of the paper are as follows: There is a com...

  9. Use of Response Surface Optimization Technique in Evaluating the ...

    African Journals Online (AJOL)

    PROF HORSFALL

    2018-04-18

    Apr 18, 2018 ... important applications in the design, development, and formulation of new products, as well as in the improvement of existing product designs, and it is an effective tool for ... Fat Max Blade Armor 35` was used to measure the .... be structure less, that is, they should contain no obvious ... desirability function.

  10. Host response to bacterially contaminated titanium and titanium alloy surfaces

    NARCIS (Netherlands)

    Yue, Chongxia

    2015-01-01

    Biomaterial-implants are frequently used to restore the function and form of human anatomy. However, the presence of implanted biomaterials dramatically elevates infection risk. Their use will increase due to an increasing life expectancy of an ever growing population world-wide. The occurrence of

  11. Surface modification by cold-plasma technique for dental implants—Bio-functionalization with binding pharmaceuticals

    Directory of Open Access Journals (Sweden)

    Masao Yoshinari

    2011-08-01

    At the bone tissue/implant interface, a thin calcium phosphate coating and rapid heating with infrared radiation were effective in controlling the dissolution without cracking the coating. These thin calcium phosphate coatings may directly promote osteogenisis, but also enable immobilization and subsequent drug delivery system (DDS of bisphosphonates. Simvastatin is also an effective candidate that is reported to increase the expression of BMP-2. The thin-film of hexamethyldisiloxane (HMDSO was plasma-polymerized onto titanium, and then HMDSO surface was activated by O2-plasma treatment. A quartz crystal microbalance (QCM-D technique demonstrated that simvastatin was immobilized on the plasma-treated surfaces due to introduction of O2-functional groups. At the soft tissue/implant interface, multi-grooved surface topographies and utilizing the adhesive proteins such as fibronectin or laminin-5 may help in providing a biological seal around the implant. At the oral fluid/implant interface, an alumina coating, F+-implantation and immobilization of anti-microbial peptides were responsible for inhibiting the biofilm accumulation.

  12. UTILIZATION OF RESPONSE SURFACE METHODOLOGY IN THE OPTIMIZATION OF ROSELLE ICE CREAM MAKING [Penggunaan Response Surface Methodology dalam Optimisasi Pembuatan Es Krim Rosella

    Directory of Open Access Journals (Sweden)

    Jeremia Manuel*

    2014-12-01

    Full Text Available This research was carried out to develop a functional ice cream product with natural colorant derived from an optimum set of roselle calyces extract and citric acid concentrations. Although citric acid can improve red color stability of rosella, its addition is limited due to the acidic and bitter aftertaste it imparts. Response surface methodology (RSM was employed to analyze the effect of roselle calyces extract and citric acid on physico-chemical characteristics and sensory acceptance of an ice cream. A central composite design consisting of two independent variables (roselle calyces extract and citric acid cocentrations at five levels (-1.41421, -1, 0, +1, and +1.41421 with 13 runs (formulations was prepared to establish the optimum set of variables. Higher concentration of roselle calyces extract significantly increased the total anthocyanin content and color acceptance, while decreased the ºHue and pH of the ice cream. Higher concentration of citric acid significantly increased the overrun and color acceptance, but decreased the viscosity, ºHue, pH, texture, taste acceptance, and overall acceptance of ice cream. The optimum scores of consumer sensory acceptance were met at 11.5% roselle calyces extract and 1.5% citric acid concentrations.

  13. The impact of tool wear on the functionality of replicated polymer surface with micro structures

    DEFF Research Database (Denmark)

    Li, Dongya; Zhang, Yang; Regi, Francesco

    Wear happened frequently in the tooling process of mold for polymer production. The scope of this paper is to understand how the wear of the milling tool affected the function of the replicated polymer surface. This study is part of the process chain of fabrication of optical functional surfaces ...

  14. Gold nanostar-enhanced surface plasmon resonance biosensor based on carboxyl-functionalized graphene oxide

    International Nuclear Information System (INIS)

    Wu, Qiong; Sun, Ying; Ma, Pinyi; Zhang, Di; Li, Shuo; Wang, Xinghua; Song, Daqian

    2016-01-01

    A new high-sensitivity surface plasmon resonance (SPR) biosensor based on biofunctional gold nanostars (AuNSs) and carboxyl-functionalized graphene oxide (cGO) sheets was described. Compared with spherical gold nanoparticles (AuNPs), the anisotropic structure of AuNSs, which concentrates the electric charge density on its sharp tips, could enhance the local electromagnetic field and the electronic coupling effect significantly. cGO was obtained by a diazonium reaction of graphene oxide (GO) with 4-aminobenzoic acid. Compared with GO, cGO could immobilize more antibodies due to the abundant carboxylic groups on its surface. Testing results show that there are fairly large improvements in the analytical performance of the SPR biosensor using cGO/AuNSs-antigen conjugate, and the detection limit of the proposed biosensor is 0.0375 μg mL"−"1, which is 32 times lower than that of graphene oxide-based biosensor. - Highlights: • A sensitive and versatile SPR biosensor was constructed for detection of pig IgG. • Biofunctional gold nanostars were used to amplify the response signals. • The strategy employed carboxyl-functionalized graphene oxide as biosensing substrate. • The detection limit of the proposed biosensor is 32 times lower than that of graphene oxide-based biosensor.

  15. Gold nanostar-enhanced surface plasmon resonance biosensor based on carboxyl-functionalized graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Sun, Ying; Ma, Pinyi; Zhang, Di; Li, Shuo; Wang, Xinghua; Song, Daqian, E-mail: songdq@jlu.edu.cn

    2016-03-24

    A new high-sensitivity surface plasmon resonance (SPR) biosensor based on biofunctional gold nanostars (AuNSs) and carboxyl-functionalized graphene oxide (cGO) sheets was described. Compared with spherical gold nanoparticles (AuNPs), the anisotropic structure of AuNSs, which concentrates the electric charge density on its sharp tips, could enhance the local electromagnetic field and the electronic coupling effect significantly. cGO was obtained by a diazonium reaction of graphene oxide (GO) with 4-aminobenzoic acid. Compared with GO, cGO could immobilize more antibodies due to the abundant carboxylic groups on its surface. Testing results show that there are fairly large improvements in the analytical performance of the SPR biosensor using cGO/AuNSs-antigen conjugate, and the detection limit of the proposed biosensor is 0.0375 μg mL{sup −1}, which is 32 times lower than that of graphene oxide-based biosensor. - Highlights: • A sensitive and versatile SPR biosensor was constructed for detection of pig IgG. • Biofunctional gold nanostars were used to amplify the response signals. • The strategy employed carboxyl-functionalized graphene oxide as biosensing substrate. • The detection limit of the proposed biosensor is 32 times lower than that of graphene oxide-based biosensor.

  16. Calculating the sensitivity of wind turbine loads to wind inputs using response surfaces

    DEFF Research Database (Denmark)

    Rinker, Jennifer M.

    2016-01-01

    at a low computational cost. Sobol sensitivity indices (SIs) can then be calculated with relative ease using the calibrated response surface. The proposed methodology is demonstrated by calculating the total sensitivity of the maximum blade root bending moment of the WindPACT 5 MW reference model to four......This paper presents a methodology to calculate wind turbine load sensitivities to turbulence parameters through the use of response surfaces. A response surface is a high-dimensional polynomial surface that can be calibrated to any set of input/output data and then used to generate synthetic data...... turbulence input parameters: a reference mean wind speed, a reference turbulence intensity, the Kaimal length scale, and a novel parameter reflecting the nonstationarity present in the inflow turbulence. The input/output data used to calibrate the response surface were generated for a previous project...

  17. Primary role of electron work function for evaluation of nanostructured titania implant surface against bacterial infection

    Energy Technology Data Exchange (ETDEWEB)

    Golda-Cepa, M., E-mail: golda@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Syrek, K. [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Brzychczy-Wloch, M. [Department of Bacteriology, Microbial Ecology and Parasitology, Jagiellonian University Medical College, Czysta 18, 31-121 Krakow (Poland); Sulka, G.D. [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Kotarba, A., E-mail: kotarba@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland)

    2016-09-01

    The electron work function as an essential descriptor for the evaluation of metal implant surfaces against bacterial infection is identified for the first time. Its validity is demonstrated on Staphylococcus aureus adhesion to nanostructured titania surfaces. The established correlation: work function–bacteria adhesion is of general importance since it can be used for direct evaluation of any electrically conductive implant surfaces. - Highlights: • The correlation between work function and bacteria adhesion was discovered. • The discovered correlation is rationalized in terms of electrostatic bacteria–surface repulsion. • The results provide basis for the simple evaluation of implant surfaces against infection.

  18. An expert system to characterize the surface morphological properties according to their functionalities

    International Nuclear Information System (INIS)

    Bigerelle, M; Mathia, T; Iost, A; Correvits, T; Anselme, K

    2011-01-01

    In this paper we propose a new methodology to characterize the morphological properties of a surface in relation with its functionality (tribological properties, surface coating adhesion, brightness, wettability...). We create a software based on experimental design and surface profile recording. Using an appropriate database structure, the roughness parameters are automatically computed at different scales. The surface files are saved in a hard disk directory and roughness parameters are computed at different scales. Finally, a statistical analysis system proposes the roughness parameter (or the pair of roughness parameters) that better describe(s) the functionality of the surface and the spatial scales at which the parameter(s) is (are) the more relevant.

  19. An expert system to characterize the surface morphological properties according to their functionalities

    Energy Technology Data Exchange (ETDEWEB)

    Bigerelle, M [Laboratoire Roberval, UMR 6253, UTC/CNRS, UTC Centre de Recherches de Royallieu BP 20529, 60205 Compiegne France stol BS1 6BE (United Kingdom); Mathia, T [Laboratoire de Tribologie et Dynamique des Systemes, UMR 5513, Ecole Centrale de Lyon, 36 Av Guy de Collongue, 69134 Ecully Cedex (France); Iost, A [Laboratoire de Mecanique de Lille, UMR CNRS 8107, Arts et Metiers ParisTech - Lille, 8, boulevard Louis XIV 59046 Lille (France); Correvits, T [Laboratoire de Metrologie. Arts et Metiers ParisTech, ENSAM, 8 boulevard Louis XIV, 59046 LILLE Cedex (France); Anselme, K, E-mail: maxence.bigerelle@utc.fr [Institut De Sciences Des Materiaux De Mulhouse, CNRS LRC 7228, 15, rue Jean Starcky, Universite De Haute-Alsace, BP 2488, 68057 Mulhouse (France)

    2011-08-19

    In this paper we propose a new methodology to characterize the morphological properties of a surface in relation with its functionality (tribological properties, surface coating adhesion, brightness, wettability...). We create a software based on experimental design and surface profile recording. Using an appropriate database structure, the roughness parameters are automatically computed at different scales. The surface files are saved in a hard disk directory and roughness parameters are computed at different scales. Finally, a statistical analysis system proposes the roughness parameter (or the pair of roughness parameters) that better describe(s) the functionality of the surface and the spatial scales at which the parameter(s) is (are) the more relevant.

  20. Primary role of electron work function for evaluation of nanostructured titania implant surface against bacterial infection

    International Nuclear Information System (INIS)

    Golda-Cepa, M.; Syrek, K.; Brzychczy-Wloch, M.; Sulka, G.D.; Kotarba, A.

    2016-01-01

    The electron work function as an essential descriptor for the evaluation of metal implant surfaces against bacterial infection is identified for the first time. Its validity is demonstrated on Staphylococcus aureus adhesion to nanostructured titania surfaces. The established correlation: work function–bacteria adhesion is of general importance since it can be used for direct evaluation of any electrically conductive implant surfaces. - Highlights: • The correlation between work function and bacteria adhesion was discovered. • The discovered correlation is rationalized in terms of electrostatic bacteria–surface repulsion. • The results provide basis for the simple evaluation of implant surfaces against infection.

  1. Monolayer assembly and striped architecture of Co nanoparticles on organic functionalized Si surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bae, S.-S.; Lim, D.K.; Park, J.-I.; Kim, S. [Korea Advanced Institute of Science and Technology, Department of Chemistry and School of Molecular Science (BK 21), Daejeon (Korea); Cheon, J. [Yonsei University, Department of Chemistry, College of Sciences, Seoul (Korea); Jeon, I.C. [Chonbuk National University, Department of Chemistry, College of Natural Sciences, Chonbuk (Korea)

    2005-03-01

    We present a new strategy to fabricate a monolayer assembly of Br-terminated Co nanoparticles on functionalized Si surfaces by using chemical covalent bonding and microcontact printing method. Self-assembled monolayers (SAMs) of the Co nanoparticles formed on the hydroxyl-terminated Si surface exhibit two-dimensional island networks with locally ordered arrays via covalent linkage between nanoparticles and surface. On the other hand, SAMs of the nanoparticles on the aminopropyl-terminated Si surface show an individual and random distribution over an entire surface. Furthermore, we have fabricated striped architectures of Co nanoparticles using a combination of microcontact printing and covalent linkage. Microcontact printing of octadecyltrichlorosilane and selective covalent linkage between nanoparticles and functionalized Si surfaces lead to a hybrid nanostructure with selectively assembled nanoparticles stripes on the patterned functionalized Si surfaces. (orig.)

  2. Application of Response Surface Methodology in Optimizing a Three Echelon Inventory System

    Directory of Open Access Journals (Sweden)

    Seyed Hossein Razavi Hajiagha

    2014-01-01

    Full Text Available Inventory control is an important subject in supply chain management. In this paper, a three echelon production, distribution, inventory system composed of one producer, two wholesalers and a set of retailers has been considered. Costumers' demands follow a compound Poisson process and the inventory policy is a kind of continuous review (R, Q. In this paper, regarding the standard cost structure in an inventory model, the cost function of system has been approximated using Response Surface Methodology as a combination of designed experiments, simulation, regression analysis and optimization. The proposed methodology in this paper can be applied as a novel method in optimization of inventory policy of supply chains. Also, the joint optimization of inventory parameters, including reorder point and batch order size, is another advantage of the proposed methodology.

  3. Calculating the sensitivity of wind turbine loads to wind inputs using response surfaces

    International Nuclear Information System (INIS)

    Rinker, Jennifer M.

    2016-01-01

    This paper presents a methodology to calculate wind turbine load sensitivities to turbulence parameters through the use of response surfaces. A response surface is a highdimensional polynomial surface that can be calibrated to any set of input/output data and then used to generate synthetic data at a low computational cost. Sobol sensitivity indices (SIs) can then be calculated with relative ease using the calibrated response surface. The proposed methodology is demonstrated by calculating the total sensitivity of the maximum blade root bending moment of the WindPACT 5 MW reference model to four turbulence input parameters: a reference mean wind speed, a reference turbulence intensity, the Kaimal length scale, and a novel parameter reflecting the nonstationarity present in the inflow turbulence. The input/output data used to calibrate the response surface were generated for a previous project. The fit of the calibrated response surface is evaluated in terms of error between the model and the training data and in terms of the convergence. The Sobol SIs are calculated using the calibrated response surface, and the convergence is examined. The Sobol SIs reveal that, of the four turbulence parameters examined in this paper, the variance caused by the Kaimal length scale and nonstationarity parameter are negligible. Thus, the findings in this paper represent the first systematic evidence that stochastic wind turbine load response statistics can be modeled purely by mean wind wind speed and turbulence intensity. (paper)

  4. Improved adhesion of Ag NPs to the polyethylene terephthalate surface via atmospheric plasma treatment and surface functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Tao [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Liu, Yong [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Solmont Technology Wuxi Co., Ltd. 228 Linghu Blvd. Tianan Tech Park, A1-602, Xinwu District, Wuxi, Jiangsu 214135 (China); Zhu, Yan, E-mail: zhuyan@kmust.edu.cn [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Yang, De-Quan, E-mail: dequan.yang@gmail.com [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Solmont Technology Wuxi Co., Ltd. 228 Linghu Blvd. Tianan Tech Park, A1-602, Xinwu District, Wuxi, Jiangsu 214135 (China); Sacher, Edward [Regroupement Québécois de Matériaux de Pointe, Department of Engineering Physics, École Polytechnique de Montréal, Case Postale 6079, succursale Centre-Ville, Montréal, Québec H3C 3A7 (Canada)

    2017-07-31

    Highlights: • A two-step process has been developed to enhance the adhesion of immobilized Ag NPs to the PET surface. • The method is simple, easy to use and low-cost for mass production. • The increased density of active sites (−OH, −CH=O and COOH) at the PET surface, after plasma treatment, permits increased reaction with 3-aminopropyltriethoxysilane (APTES). • The presence of APTES with high surface density permits −NH{sub 2}-Ag complex formation, increasing the adhesion of the Ag NPs. - Abstract: Ag nanoparticles (NPs) have been widely applied, as important antibacterial materials, on textile and polymer surfaces. However, their adhesion to nonreactive polymer surfaces is generally too weak for many applications. Here, we propose a two-step process, atmospheric plasma treatment followed by a surface chemical modification process, which enhances their adhesion to polyethylene terephthalate (PET) surfaces. We found that, compared to either plasma treatments or surface chemical functionalizations, alone, this combination greatly enhanced their adhesion. The plasma treatment resulted in an increase of active sites (−OH, −CH=O and COOH) at the PET surface, permitting increased bonding to 3-aminopropyltriethoxysilane (APTES), whose −NH{sub 2} groups were then able to form a bonding complex with the Ag NPs.

  5. Spatial prediction of near surface soil water retention functions using hydrogeophysics and empirical orthogonal functions

    Science.gov (United States)

    Gibson, Justin; Franz, Trenton E.

    2018-06-01

    The hydrological community often turns to widely available spatial datasets such as the NRCS Soil Survey Geographic database (SSURGO) to characterize the spatial variability of soil properties. When used to spatially characterize and parameterize watershed models, this has served as a reasonable first approximation when lacking localized or incomplete soil data. Within agriculture, soil data has been left relatively coarse when compared to numerous other data sources measured. This is because localized soil sampling is both expensive and time intense, thus a need exists in better connecting spatial datasets with ground observations. Given that hydrogeophysics is data-dense, rapid, non-invasive, and relatively easy to adopt, it is a promising technique to help dovetail localized soil sampling with spatially exhaustive datasets. In this work, we utilize two common near surface geophysical methods, cosmic-ray neutron probe and electromagnetic induction, to identify temporally stable spatial patterns of measured geophysical properties in three 65 ha agricultural fields in western Nebraska. This is achieved by repeat geophysical observations of the same study area across a range of wet to dry field conditions in order to evaluate with an empirical orthogonal function. Shallow cores were then extracted within each identified zone and water retention functions were generated in the laboratory. Using EOF patterns as a covariate, we quantify the predictive skill of estimating soil hydraulic properties in areas without measurement using a bootstrap validation analysis. Results indicate that sampling locations informed via repeat hydrogeophysical surveys, required only five cores to reduce the cross-validation root mean squared error by an average of 64% as compared to soil parameters predicted by a commonly used benchmark, SSURGO and ROSETTA. The reduction to five strategically located samples within the 65 ha fields reduces sampling efforts by up to ∼90% as compared to

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    Highlights: • An in situ plasma processing for SNS SRF cavities has been developed to remove hydrocarbons from cavity surface. • Reactive oxygen plasma is very effective to remove hydrocarbons from niobium top surface. • Reactive oxygen plasma processing increases the work function of niobium surface in the range of 0.5–1.0 eV. • It was observed that hydrocarbons can migrate at plasma cleaned top surface from near surface regions when waiting in vacuum at room temperature. • Multiple cycles of plasma processing with waiting periods in between was found beneficial to mitigate such hydrocarbons migration at plasma cleaned surface. - Abstract: 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.

  7. Nuclear response functions at large energy and momentum transfer

    International Nuclear Information System (INIS)

    Bertozzi, W.; Moniz, E.J.; Lourie, R.W.

    1991-01-01

    Quasifree nucleon processes are expected to dominate the nuclear electromagnetic response function for large energy and momentum transfers, i.e., for energy transfers large compared with nuclear single particle energies and momentum transfers large compared with typical nuclear momenta. Despite the evident success of the quasifree picture in providing the basic frame work for discussing and understanding the large energy, large momentum nuclear response, the limits of this picture have also become quite clear. In this article a selected set of inclusive and coincidence data are presented in order to define the limits of the quasifree picture more quantitatively. Specific dynamical mechanisms thought to be important in going beyond the quasifree picture are discussed as well. 75 refs, 37 figs

  8. The effect of polyether functional polydimethylsiloxane on surface and thermal properties of waterborne polyurethane

    Science.gov (United States)

    Zheng, Guikai; Lu, Ming; Rui, Xiaoping

    2017-03-01

    Waterborne polyurethanes (WPU) modified with polyether functional polydimethylsiloxane (PDMS) were synthesized by pre-polymerization method using isophorone diisocyanate (IPDI) and 1,4-butanediol (BDO) as hard segments and polybutylene adipate glycol (PBA) and polyether functional PDMS as soft segments. The effect of polyether functional PDMS on phase separation, thermal properties, surface properties including surface composition, morphology and wettability were investigated by FTIR, contact angle measurements, ARXPS, SEM-EDS, AFM, TG and DSC. The results showed that the compatibility between urethane hard segment and PDMS modified with polyether was good, and there was no distinct phase separation in both bulk and surface of WPU films. The degradation temperature and low temperature flexibility increased with increasing amounts of polyether functional PDMS. The enrichment of polyether functional PDMS with low surface energy on the surface imparted excellent hydrophobicity to WPU films.

  9. Correlation of H- production and the work function of a surface in a hydrogen plasma

    International Nuclear Information System (INIS)

    Wada, M.

    1983-03-01

    Surface-plasma negative hydrogen ion sources are being developed as possible parts for future neutral beam systems. In these ion sources, negative hydrogen ions (H - ) are produced at low work function metal surfaces immersed in hydrogen plasmas. To investigate the correlation between the work function and the H - production at the surface with a condition similar to the one in the actual plasma ion source, these two parameters were simultaneously measured in the hydrogen plasma environment

  10. Response surface methodology for sensitivity and uncertainty analysis: performance and perspectives

    International Nuclear Information System (INIS)

    Olivi, L.; Brunelli, F.; Cacciabue, P.C.; Parisi, P.

    1985-01-01

    Two main aspects have to be taken into account in studying a nuclear accident scenario when using nuclear safety codes as an information source. The first one concerns the behavior of the code response and the set of assumptions to be introduced for its modelling. The second one is connected with the uncertainty features of the code input, often modelled as a probability density function (pdf). The analyst can apply two well-defined approaches depending on whether he wants major emphasis put on either of the aspects. Response Surface Methodology uses polynomial and inverse polynomial models together with the theory of experimental design, expressly developed for the identification procedure. It constitutes a well-established body of techniques able to cover a wide spectrum of requirements, when the first aspect plays the crucial role in the definition of the objectives. Other techniques such as Latin hypercube sampling, stratified sampling or even random sampling can fit better, when the second aspect affects the reliability of the analysis. The ultimate goal for both approaches is the selection of the variable, i.e. the identification of the code input variables most effective on the output and the uncertainty propagation, i.e. the assessment of the pdf to be attributed to the code response. The main aim of this work is to present a sensitivity analysis method, already tested on a real case, sufficiently flexible to be applied in both approaches mentioned

  11. Exactly solvable model for the time response function of RPCs

    International Nuclear Information System (INIS)

    Mangiarotti, A.; Fonte, P.; Gobbi, A.

    2004-01-01

    The fluctuation theory for the growth of several avalanches is briefly summarized and extended to include the case of electronegative gas mixtures. Based on such physical picture, the intrinsic time response function of an RPC can be calculated in a closed form and its average and rms extracted from series representations. The corresponding timing resolution, expressed in units of 1/((α-η)vd), is a universal function of the mean number of 'effective' clusters n0 reduced by electron attachment: n0(1-η/α). A comparison to a few selected good-quality experimental data is attempted for the timing resolution of both 1-gap and 4-gaps RPCs, finding a reasonable agreement

  12. Surface functionalization of cellulose by grafting oligoether chains

    International Nuclear Information System (INIS)

    Ly, El hadji Babacar; Bras, Julien; Sadocco, Patrizia; Belgacem, Mohamed Naceur; Dufresne, Alain; Thielemans, Wim

    2010-01-01

    Two cellulosic substrates (Whatman paper and wood fibres) were chemically modified using different oligoether chains; poly(ethylene) (POE), poly(propylene) (PPG) and poly(tetrahydrofuran) (PTHF) glycols with different lengths were first converted into mono-NCO-terminating macromolecules to allow direct grafting to the cellulose substrates. This step was achieved by reacting the chosen oligoether with 2,4-toluene diisocyanate. The prepared macromolecular grafts were then coupled with the cellulose surface and the resulting treated substrates were fully characterized by contact angle measurements, elemental analysis, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Thus, all the techniques implemented showed clear evidence of successful grafting, namely: (i) when using PPG grafts, the polar contribution to the surface energy decreased from approximately 25 to virtually 0 mJ m -2 and the wettability by water decreased, as the water contact angle shifted from around 40 to above 90 o ; (ii) nitrogen atoms were detected by elemental analysis and XPS; (iii) the aliphatic carbon contents increased from 11 to about 39-50%, depending on the oligoether used; and (iv) small spheres having about 100 nm diameter were detected by SEM. Moreover, the grafted fibres were submitted to biodegradation tests which showed that they conserved their biodegradable character, although with a slower biodegradation rate. The novelty of the present paper is the direct grafting of the polymeric matrix onto the fibre surface thanks to a new modification strategy involving the use of a diisocyanate as a mediator between the matrix and the reinforcing elements. The covalently linked polymeric chains constituting the matrix could melt under heating, thus, yielding the interdiffusion of the macromolecular grafts and forming the composite.

  13. Quantitative Evaluation of Bioorthogonal Chemistries for Surface Functionalization of Nanoparticles

    DEFF Research Database (Denmark)

    Feldborg, Lise Nørkjær; Jølck, Rasmus Irming; Andresen, Thomas Lars

    2012-01-01

    We present here a highly efficient and chemoselective liposome functionalization method based on oxime bond formation between a hydroxylamine and an aldehyde-modified lipid component. We have conducted a systematic and quantitative comparison of this new approach with other state-of-the-art conju...

  14. Near-surface groundwater responses to injection of geothermal wastes

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, S.C.

    1984-06-01

    Experiences with injecting geothermal fluids have identified technical problems associated with geothermal waste disposal. This report assesses the feasibility of injection as an alternative for geothermal wastewater disposal and analyzes hydrologic controls governing the upward migration of injected fluids. Injection experiences at several geothermal developments are presented, including: Raft River, Salton Sea, East Mesa, Otake and Hatchobaru in Japan, and Ahuachapan in El Salvador. Hydrogeologic and design/operational factors affecting the success of an injection program are identified. Hydrogeologic factors include subsidence, near-surface effects of injected fluids, and seismicity. Design/operational factors include hydrodynamic breakthrough, condition of the injection system and reservoir maintenance. Existing and potential effects of production/injection on these factors are assessed.

  15. Artificial hairy surfaces with a nearly perfect hydrophobic response.

    Science.gov (United States)

    Hsu, Shu-Hau; Sigmund, Wolfgang M

    2010-02-02

    A nearly perfect hydrophobic interface by dint of mimicking hairs of arthropods was achieved for the first time. These Gamma-shape artificial hairs were made via a membrane casting technique on polypropylene substrates. This extreme hydrophobicity merely arises from microstructure modification, and no further chemical treatments are needed. The ultralow adhesion to water droplets was evaluated through video assessment, and it is believed to be attributed to the mechanical response of the artificial hairs. The principle of this fabrication technique is accessible and is expected to be compatible with large-area fabrication of superhydrophobic interfaces.

  16. Microarray of neuroblastoma cells on the selectively functionalized nanocrystalline diamond thin film surface

    International Nuclear Information System (INIS)

    Park, Young-Sang; Son, Hyeong-Guk; Kim, Dae-Hoon; Oh, Hong-Gi; Lee, Da-Som; Kim, Min-Hye; Lim, Ki-Moo; Song, Kwang-Soup

    2016-01-01

    Graphical abstract: - Highlights: • The nanocrystalline diamond (NCD) surface is functionalized with F or O. • The cell adhesion and growth are evaluated on the functionalized NCD surface. • The cell adhesion and growth depend on the wettability of the surface. • Cell patterning was achieved by using of hydrophilic and hydrophobic surfaces. • Neuroblastoma cells were arrayed on the micro-patterned NCD surface. - Abstract: Nanocrystalline diamond (NCD) film surfaces were modified with fluorine or oxygen by plasma treatment in an O_2 or C_3F_8 gas environment in order to induce wettability. The oxygenated-NCD (O-NCD) film surface was hydrophilic and the fluorinated-NCD (F-NCD) surface was hydrophobic. The efficiency of early cell adhesion, which is dependent on the wettability of the cell culture plate and necessary for the growth and proliferation of cells, was 89.62 ± 3.92% on the O-NCD film and 7.78 ± 0.77% on the F-NCD film surface after 3 h of cell culture. The wettability of the NCD film surface was artificially modified using a metal mask and plasma treatment to fabricate a micro-pattern. Four types of micro-patterns were fabricated (line, circle, mesh, and word) on the NCD film surface. We precisely arrayed the neuroblastoma cells on the micro-patterned NCD film surfaces by controlling the surface wettability and cell seeding density. The neuroblastoma cells adhered and proliferated along the O-NCD film surface.

  17. Optimization of mucilage extraction from chia seeds (Salvia hispanica L.) using response surface methodology.

    Science.gov (United States)

    Orifici, Stefania C; Capitani, Marianela I; Tomás, Mabel C; Nolasco, Susana M

    2018-02-25

    Chia mucilage has potential application as a functional ingredient; advances on maximizing its extraction yield could represent a significant technological and economic impact for the food industry. Thus, first, the effect of mechanical agitation time (1-3 h) on the exudation of chia mucilage was analyzed. Then, response surface methodology was used to determine the optimal combination of the independent variables temperature (15-85 °C) and seed: water ratio (1: 12-1: 40.8 w/v) for the 2 h exudation that give maximum chia mucilage yield. Experiments were designed according to central composite rotatable design. A second-order polynomial model predicted the variation in extraction mucilage yield with the variables temperature and seed: water ratio. The optimal operating conditions were found to be temperature 85 °C and a seed: water ratio of 1: 31 (w/v), reaching an experimental extraction yield of 116 ± 0.21 g kg -1 (dry basis). The mucilage obtained exhibited good functional properties, mainly in terms of water-holding capacity, emulsifying activity, and emulsion stability. The results obtained show that temperature, seed: water ratio, and exudation time are important variables of the process that affect the extraction yield and the quality of the chia mucilage, determined according to its physicochemical and functional properties. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

  18. Spatial Control of Functional Response in 4D-Printed Active Metallic Structures

    Science.gov (United States)

    Ma, Ji; Franco, Brian; Tapia, Gustavo; Karayagiz, Kubra; Johnson, Luke; Liu, Jun; Arroyave, Raymundo; Karaman, Ibrahim; Elwany, Alaa

    2017-04-01

    We demonstrate a method to achieve local control of 3-dimensional thermal history in a metallic alloy, which resulted in designed spatial variations in its functional response. A nickel-titanium shape memory alloy part was created with multiple shape-recovery stages activated at different temperatures using the selective laser melting technique. The multi-stage transformation originates from differences in thermal history, and thus the precipitate structure, at various locations created from controlled variations in the hatch distance within the same part. This is a first example of precision location-dependent control of thermal history in alloys beyond the surface, and utilizes additive manufacturing techniques as a tool to create materials with novel functional response that is difficult to achieve through conventional methods.

  19. Optimum extrusion-cooking conditions for improving physical properties of fish-cereal based snacks by response surface methodology.

    Science.gov (United States)

    Singh, R K Ratankumar; Majumdar, Ranendra K; Venkateshwarlu, G

    2014-09-01

    To establish the effect of barrel temperature, screw speed, total moisture and fish flour content on the expansion ratio and bulk density of the fish based extrudates, response surface methodology was adopted in this study. The experiments were optimized using five-levels, four factors central composite design. Analysis of Variance was carried to study the effects of main factors and interaction effects of various factors and regression analysis was carried out to explain the variability. The fitting was done to a second order model with the coded variables for each response. The response surface plots were developed as a function of two independent variables while keeping the other two independent variables at optimal values. Based on the ANOVA, the fitted model confirmed the model fitness for both the dependent variables. Organoleptically highest score was obtained with the combination of temperature-110(0) C, screw speed-480 rpm, moisture-18 % and fish flour-20 %.

  20. Nano-anisotropic surface coating based on drug immobilized pendant polymer to suppress macrophage adhesion response.

    Science.gov (United States)

    Kaladhar, K; Renz, H; Sharma, C P

    2015-04-01

    Exploring drug molecules for material design, to harness concepts of nano-anisotropy and ligand-receptor interactions, are rather elusive. The aim of this study is to demonstrate the bottom-up design of a single-step and bio-interactive polymeric surface coating, based on drug based pendant polymer. This can be applied on to polystyrene (PS) substrates, to suppress macrophage adhesion and spreading. The drug molecule is used in this coating for two purposes. The first one is drug as a "pendant" group, to produce nano-anisotropic properties that can enable adhesion of the coatings to the substrate. The second purpose is to use the drug as a "ligand", to produce ligand-receptor interaction, between the bound ligand and receptors of albumin, to develop a self-albumin coat over the surface, by the preferential binding of albumin in biological environment, to reduce macrophage adhesion. Our in silico studies show that, diclofenac (DIC) is an ideal drug based "ligand" for albumin. This can also act as a "pendant" group with planar aryl groups. The combination of these two factors can help to harness, both nano-anisotropic properties and biological functions to the polymeric coating. Further, the drug, diclofenac (DIC) is immobilized to the polyvinyl alcohol (PVA), to develop the pendant polymer (PVA-DIC). The interaction of bound DIC with the albumin is a ligand-receptor based interaction, as per the studies by circular dichroism, differential scanning calorimetry, and SDS-PAGE. The non-polar π-π* interactions are regulating; the interactions between PVA bound DIC-DIC interactions, leading to "nano-anisotropic condensation" to form distinct "nano-anisotropic segments" inside the polymeric coating. This is evident from, the thermo-responsiveness and uniform size of nanoparticles, as well as regular roughness in the surface coating, with similar properties as that of nanoparticles. In addition, the hydrophobic DIC-polystyrene (PS) interactions, between the PVA

  1. Surface regulated arsenenes as Dirac materials: From density functional calculations

    International Nuclear Information System (INIS)

    Yuan, Junhui; Xie, Qingxing; Yu, Niannian; Wang, Jiafu

    2017-01-01

    Highlights: • The presence of Dirac cones in chemically decorated buckled arsenene AsX (X = CN, NC, NCO, NCS, and NCSe) has been revealed. • First-principles calculations show that all these chemically decorated arsenenes are kinetically stable in defending thermal fluctuations in room temperature. - Abstract: Using first principle calculations based on density functional theory (DFT), we have systematically investigated the structure stability and electronic properties of chemically decorated arsenenes, AsX (X = CN, NC, NCO, NCS and NCSe). Phonon dispersion and formation energy analysis reveal that all the five chemically decorated buckled arsenenes are energetically favorable and could be synthesized. Our study shows that wide-bandgap arsenene would turn into Dirac materials when functionalized by -X (X = CN, NC, NCO, NCS and NCSe) groups, rendering new promises in next generation high-performance electronic devices.

  2. Effect of extracytoplasmic function sigma factors on autoaggregation, hemagglutination, and cell surface properties of Porphyromonas gingivalis

    Science.gov (United States)

    Kokubu, Eitoyo; Okamoto-Shibayama, Kazuko; Ishihara, Kazuyuki

    2017-01-01

    Porphyromonas gingivalis is a bacterium frequently isolated from chronic periodontal lesions and is involved in the development of chronic periodontitis. To colonize the gingival crevice, P. gingivalis has to adapt to environmental stresses. Microbial gene expression is regulated by transcription factors such as those in two-component systems and extracytoplasmic function (ECF) sigma factors. ECF sigma factors are involved in the regulation of environmental stress response genes; however, the roles of individual ECF sigma factors are largely unknown. The purpose of this study was to investigate the functions, including autoaggregation, hemagglutination, gingipain activity, susceptibility to antimicrobial agents, and surface structure formation, of P. gingivalis ECF sigma factors encoded by SigP (PGN_0274), SigCH (PGN_0319), PGN_0450, PGN_0970, and SigH (PGN_1740). Various physiological aspects of the sigP mutant were affected; autoaggregation was significantly decreased at 60 min (p < 0.001), hemagglutination activity was markedly reduced, and enzymatic activities of Kgp and Rgps were significantly decreased (p < 0.001). The other mutants also showed approximately 50% reduction in Rgps activity. Kgp activity was significantly reduced in the sigH mutant (p < 0.001). No significant differences in susceptibilities to tetracycline and ofloxacin were observed in the mutants compared to those of the wild-type strain. However, the sigP mutant displayed an increased susceptibility to ampicillin, whereas the PGN_0450 and sigH mutants showed reduced susceptibility. Transmission electron microscopy images revealed increased levels of outer membrane vesicles formed at the cell surfaces of the sigP mutant. These results indicate that SigP is important for bacterial surface-associated activities, including gingipain activity, autoaggregation, hemagglutination, vesicle formation, and antimicrobial susceptibility. PMID:28931045

  3. Converting chemical energy into electricity through a functionally cooperating device with diving-surfacing cycles.

    Science.gov (United States)

    Song, Mengmeng; Cheng, Mengjiao; Ju, Guannan; Zhang, Yajun; Shi, Feng

    2014-11-05

    A smart device that can dive or surface in aqueous medium has been developed by combining a pH-responsive surface with acid-responsive magnesium. The diving-surfacing cycles can be used to convert chemical energy into electricity. During the diving-surfacing motion, the smart device cuts magnetic flux lines and produces a current, demonstrating that motional energy can be realized by consuming chemical energy of magnesium, thus producing electricity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Functions of microRNA in response to cocaine stimulation.

    Science.gov (United States)

    Xu, L-F; Wang, J; Lv, F B; Song, Q

    2013-12-04

    MicroRNAs (miRNAs) are a type of non-protein-coding single-stranded RNA, which are typically 20-25 nt in length. miRNAs play important roles in various biological processes, including development, cell proliferation, differentiation, and apoptosis. We aimed to detect the miRNA response to cocaine stimulations and their target genes. Using the miRNA expression data GSE21901 downloaded from the Gene Expression Omnibus database, we screened out the differentially expressed miRNA after short-term (1 h) and longer-term (6 h) cocaine stimulations based on the fold change >1.2. Target genes of differentially expressed miRNAs were retrieved from TargetScan database with the context score -0.3. Functional annotation enrichment analysis was performed for all the target genes with DAVID. A total of 121 differentially expressed miRNAs between the 1-h treatment and the control samples, 58 between the 6-h treatment and the control samples, and 69 between the 1-h and the 6-h treatment samples. Among them, miR-212 results of particular interest, since its expression level was constantly elevated responding to cocaine treatment. After functional and pathway annotations of target genes, we proved that miR-212 was a critical element in cocaine-addiction, because of its involvement in regulating several important cell cycle events. The results may pave the way for further understanding the regulatory mechanisms of cocaine-response in human bodies.

  5. Study on response function of CdTe detector

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyunduk; Cho, Gyuseong [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Kang, Bo-Sun [Department of Radiological Science, Catholic University of Daegu, Kyoungsan, Kyoungbuk 712-702 (Korea, Republic of)], E-mail: bskang@cu.ac.kr

    2009-10-21

    So far the origin of the mechanism of light emission in the sonoluminescence has not elucidated whether it is due to blackbody radiation or bremsstrahlung. The final goal of our study is measuring X-ray energy spectrum using high-sensitivity cadmium telluride (CdTe) detector in order to obtain information for understanding sonoluminescence phenomena. However, the scope of this report is the measurement of X-ray spectrum using a high-resolution CdTe detector and determination of CdTe detector response function to obtain the corrected spectrum from measured soft X-ray source spectrum. In general, the measured spectrum was distorted by the characteristics of CdTe detector. Monte Carlo simulation code, MCNP, was used to obtain the reference response function of the CdTe detector. The X-ray spectra of {sup 57}Co, {sup 133}Ba, and {sup 241}Am were obtained by a 4x4x1.0(t) mm{sup 3} CdTe detector at room temperature.

  6. Visual functions in amblyopia as determinants of response to treatment.

    Science.gov (United States)

    Singh, Vinita; Agrawal, Siddharth

    2013-01-01

    To describe the visual functions in amblyopia as determinants of response to treatment. Sixty-nine patients with unilateral and bilateral amblyopia (114 amblyopic eyes) 3 to 15 years old (mean age: 8.80 ± 2.9 years), 40 males (58%) and 29 females (42%), were included in this study. All patients were treated by conventional occlusion 6 hours per day for mild to moderate amblyopia (visual acuity 0.70 or better) and full-time for 4 weeks followed by 6 hours per day for severe amblyopia (visual acuity 0.8 or worse). During occlusion, near activities requiring hand-eye coordination were advised. The follow-up examination was done at 3 and 6 months. Improvement in visual acuity was evaluated on the logMAR chart and correlated with the visual functions. Statistical analysis was done using Wilcoxon rank sum test (Mann-Whitney U test) and Kruskal-Wallis analysis. There was a statistically significant association of poor contrast sensitivity with the grade of amblyopia (P amblyopia (P amblyopia therapy. The grade of amblyopia (initial visual acuity) and accommodation are strong determinants of response to amblyopia therapy, whereas stereopsis and mesopic visual acuity have some value as determinants. Copyright 2013, SLACK Incorporated.

  7. Surface functionalization of quantum dots with fine-structured pH-sensitive phospholipid polymer chains.

    Science.gov (United States)

    Liu, Yihua; Inoue, Yuuki; Ishihara, Kazuhiko

    2015-11-01

    To add novel functionality to quantum dots (QDs), we synthesized water-soluble and pH-responsive block-type polymers by reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers were composed of cytocompatible 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer segments, which contain a small fraction of active ester groups and can be used to conjugate biologically active compounds to the polymer, and pH-responsive poly(2-(N,N-diethylamino) ethyl methacrylate (DEAEMA)) segments. One terminal of the polymer chain had a hydrophobic alkyl group that originated from the RAFT initiator. This hydrophobic group can bind to the hydrophobic layer on the QD surface. A fluorescent dye was conjugated to the polymer chains via the active ester group. The block-type polymers have an amphiphilic nature in aqueous medium. The polymers were thus easily bound to the QD surface upon evaporation of the solvent from a solution containing the block-type polymer and QDs, yielding QD/fluorescence dye-conjugated polymer hybrid nanoparticles. Fluorescence resonance energy transfer (FRET) between the QDs (donors) and the fluorescent dye molecules (acceptors) was used to obtain information on the conformational dynamics of the immobilized polymers. Higher FRET efficiency of the QD/fluorescent dye-conjugated polymer hybrid nanoparticles was observed at pH 7.4 as compared to pH 5.0 due to a stretching-shrinking conformational motion of the poly(DEAEMA) segments in response to changes in pH. We concluded that the block-type MPC polymer-modified nanoparticles could be used to evaluate the pH of cells via FRET fluorescence based on the cytocompatibility of the MPC polymer. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Response function during oxygen sputter profiling and its application to deconvolution of ultrashallow B depth profiles in Si

    International Nuclear Information System (INIS)

    Shao Lin; Liu Jiarui; Wang Chong; Ma, Ki B.; Zhang Jianming; Chen, John; Tang, Daniel; Patel, Sanjay; Chu Weikan

    2003-01-01

    The secondary ion mass spectrometry (SIMS) response function to a B 'δ surface layer' has been investigated. Using electron-gun evaporation combined with liquid nitrogen cooling of target, we are able to deposit an ultrathin B layer without detectable island formation. The B spatial distribution obtained from SIMS is exponentially decaying with a decay length approximately a linear function of the incident energy of the oxygen during the SIMS analysis. Deconvolution with the response function has been applied to reconstruct the spatial distribution of ultra-low-energy B implants. A correction to depth and yield scales due to transient sputtering near the Si surface region was also applied. Transient erosion shifts the profile shallower, but beam mixing shifts it deeper. These mutually compensating effects make the adjusted distribution almost the same as original data. The one significant difference is a buried B peak observed near the surface region

  9. An investigation of the functional groups on the surface of activated carbons

    Directory of Open Access Journals (Sweden)

    MARYTE DERVINYTE

    2004-05-01

    Full Text Available Activated carbons were produced in the laboratory from wood using a 20-run Plackett–Burman experimental design for 19 factors. The obtained batches of activated carbon were analysed by potentiometric titration and FTIR spectroscopy to determine the surface functional groups. The results obtained by potentiometric titration displayed the distribution of individual acidity constants of those groups in the pK range. Considering this parameter, the surface functional groups were divided into carboxyl, lactone and phenol. The linear regression equations reflecting the influence of each operation used for the synthesis on the amount of these functional groups in the obtained activated carbons were generated. The FTIR spectra were used in parallel for the evaluation of the amount and the type of the surface functional groups. Relationships between the two data sets obtained by potentiometric titration and FTIR spectroscopy were evaluated by correlation analysis. It was established that the amount of surface functional groups determined by potentiometric titration positively correlates with the intensity of the peaks of hydrophilic functional groups in the FTIR spectra. At the same time, the negative correlation between potentiometrically determined amount of surface functional groups and the intensity of peaks of hydrophobic functional groups was observed. Most probably, these non-polar formations can take part in the interaction of carbon surface with H+/OH- ions and diminish the strength of existent functional groups.

  10. Surface structure and properties of functionalized nanodiamonds: a first-principles study

    International Nuclear Information System (INIS)

    Datta, Aditi; Kirca, Mesut; Fu Yao; To, Albert C

    2011-01-01

    The goal of this work is to gain fundamental understanding of the surface and internal structure of functionalized detonation nanodiamonds (NDs) using quantum mechanics based density functional theory (DFT) calculations. The unique structure of ND assists in the binding of different functional groups to its surface which in turn facilitates binding with drug molecules. The ability to comprehensively model the surface properties, as well as drug-ND interactions during functionalization, is a challenge and is the problem of our interest. First, the structure of NDs of technologically relevant size (∼5 nm) was optimized using classical mechanics based molecular mechanics simulations. Quantum mechanics based density functional theory (DFT) was then employed to analyse the properties of smaller relevant parts of the optimized cluster further to address the effect of functionalization on the stability of the cluster and reactivity at its surface. It is found that functionalization is preferred over reconstruction at the (100) surface and promotes graphitization in the (111) surface for NDs functionalized with the carbonyl oxygen (C = O) group. It is also seen that the edges of ND are the preferred sites for functionalization with the carboxyl group (-COOH) vis-a-vis the corners of ND.

  11. Surface structure and properties of functionalized nanodiamonds: a first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Datta, Aditi; Kirca, Mesut; Fu Yao; To, Albert C, E-mail: albertto@pitt.edu [Department of Mechanical Engineering and Materials Science and Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States)

    2011-02-11

    The goal of this work is to gain fundamental understanding of the surface and internal structure of functionalized detonation nanodiamonds (NDs) using quantum mechanics based density functional theory (DFT) calculations. The unique structure of ND assists in the binding of different functional groups to its surface which in turn facilitates binding with drug molecules. The ability to comprehensively model the surface properties, as well as drug-ND interactions during functionalization, is a challenge and is the problem of our interest. First, the structure of NDs of technologically relevant size ({approx}5 nm) was optimized using classical mechanics based molecular mechanics simulations. Quantum mechanics based density functional theory (DFT) was then employed to analyse the properties of smaller relevant parts of the optimized cluster further to address the effect of functionalization on the stability of the cluster and reactivity at its surface. It is found that functionalization is preferred over reconstruction at the (100) surface and promotes graphitization in the (111) surface for NDs functionalized with the carbonyl oxygen (C = O) group. It is also seen that the edges of ND are the preferred sites for functionalization with the carboxyl group (-COOH) vis-a-vis the corners of ND.

  12. Radical Initiated Hydrosilylation on Silicon Nanocrystal Surfaces: An Evaluation of Functional Group Tolerance and Mechanistic Study.

    Science.gov (United States)

    Yang, Zhenyu; Gonzalez, Christina M; Purkait, Tapas K; Iqbal, Muhammad; Meldrum, Al; Veinot, Jonathan G C

    2015-09-29

    Hydrosilylation is among the most common methods used for modifying silicon surface chemistry. It provides a wide range of surface functionalities and effective passivation of surface sites. Herein, we report a systematic study of radical initiated hydrosilylation of silicon nanocrystal (SiNC) surfaces using two common radical initiators (i.e., 2,2'-azobis(2-methylpropionitrile) and benzoyl peroxide). Compared to other widely applied hydrosilylation methods (e.g., thermal, photochemical, and catalytic), the radical initiator based approach is particle size independent, requires comparatively low reaction temperatures, and yields monolayer surface passivation after short reaction times. The effects of differing functional groups (i.e., alkene, alkyne, carboxylic acid, and ester) on the radical initiated hydrosilylation are also explored. The results indicate functionalization occurs and results in the formation of monolayer passivated surfaces.

  13. Surface functionalization of SPR chip for specific molecular interaction analysis under flow condition

    Directory of Open Access Journals (Sweden)

    Tao Ma

    2017-03-01

    Full Text Available Surface functionalization of sensor chip for probe immobilization is crucial for the biosensing applications of surface plasmon resonance (SPR sensors. In this paper, we report a method circulating the dopamine aqueous solution to coat polydopamine film on sensing surface for surface functionalization of SPR chip. The polydopamine film with available thickness can be easily prepared by controlling the circulation time and the biorecognition elements can be immobilized on the polydopamine film for specific molecular interaction analysis. These operations are all performed under flow condition in the fluidic system, and have the advantages of easy implementation, less time consuming, and low cost, because the reagents and devices used in the operations are routinely applied in most laboratories. In this study, the specific absorption between the protein A probe immobilized on the sensing surface and human immunoglobulin G in the buffer is monitored based on this surface functionalization strategy to demonstrated its feasibility for SPR biosensing applications.

  14. Response Function of the Crayfish Caudal Photoreceptor to Hydrodynamic Stimuli

    Science.gov (United States)

    Breite, Sally; Bahar, Sonya; Neiman, Alexander; Moss, Frank

    2002-03-01

    In its abdominal 6th ganglion the crayfish houses 2 light-sensitive neurons (caudal photoreceptors, or CPRs). It is known that these neurons work in tandem with a mechanosensory system of tiny hairs spread across the tailfan, which make synaptic contact with the photoreceptors. A stochastic resonance effect has been shown in this system in which light enhances the transduction of a weak, periodic mechanosensory (hydrodynamic) stimulus. It is not known, however, whether an optimal response from the CPR is induced by a single sine wave cycle or some other waveform. We have experimentally investigated this favorable waveform by driving a tailfan preparation with mechanical 10 Hz correlated Ornstein-Uhlenbeck noise and calculating the response function from the spike-triggered average of the applied noise waveform. We will discuss differences in the shape of the optimal waveform under dark and light conditions, as well as what seems to be a noticeable difference in the magnitude of the animals' response to a noisy stimulus in comparison with a periodic stimulus.

  15. Dynamic Response of Functionally Graded Carbon Nanotube Reinforced Sandwich Plate

    Science.gov (United States)

    Mehar, Kulmani; Panda, Subrata Kumar

    2018-03-01

    In this article, the dynamic response of the carbon nanotube-reinforced functionally graded sandwich composite plate has been studied numerically with the help of finite element method. The face sheets of the sandwich composite plate are made of carbon nanotube- reinforced composite for two different grading patterns whereas the core phase is taken as isotropic material. The final properties of the structure are calculated using the rule of mixture. The geometrical model of the sandwich plate is developed and discretized suitably with the help of available shell element in ANSYS library. Subsequently, the corresponding numerical dynamic responses computed via batch input technique (parametric design language code in ANSYS) of ANSYS including Newmark’s integration scheme. The stability of the sandwich structural numerical model is established through the proper convergence study. Further, the reliability of the sandwich model is checked by comparison study between present and available results from references. As a final point, some numerical problems have been solved to examine the effect of different design constraints (carbon nanotube distribution pattern, core to face thickness ratio, volume fractions of the nanotube, length to thickness ratio, aspect ratio and constraints at edges) on the time-responses of sandwich plate.

  16. Experimental and statistical analysis of surface charge, aggregation and adsorption behaviors of surface-functionalized titanium dioxide nanoparticles in aquatic system

    Energy Technology Data Exchange (ETDEWEB)

    Xiang Chengcheng [West Virginia University, Department of Mechanical and Aerospace Engineering, WVNano Initiative (United States); Yang Feng, E-mail: feng.yang@mail.wvu.edu [West Virginia University, Department of Industrial and Management Systems Engineering (United States); Li Ming [West Virginia University, Department of Mechanical and Aerospace Engineering, WVNano Initiative (United States); Jaridi, Majid [West Virginia University, Department of Industrial and Management Systems Engineering (United States); Wu Nianqiang, E-mail: nick.wu@mail.wvu.edu [West Virginia University, Department of Mechanical and Aerospace Engineering, WVNano Initiative (United States)

    2013-01-15

    One hundred and fifty nanometers sized anatase titanium dioxide nanoparticles (TiO{sub 2} NPs) have been functionalized with the -CH{sub 3}, -NH{sub 2}, -SH, -OH, -COOH, and -SO{sub 3}H terminal groups. Surface charge, aggregation, and adsorption behaviors of the functionalized NPs in aquatic phase have been investigated by a set of experiments following the full factorial design. The dependence of surface charge, suspension size, and surface adsorption upon the various factors (including surface chemistry of NPs, the pH value, and ionic strength of an aqueous solution) has been studied with the statistical methods such as multiple linear regressions and multiple comparison tests. The surface functional group on the TiO{sub 2} NPs affects the characteristics in the simulated aquatic environment. The correlations among the characteristics of NPs have also been investigated by obtaining Pearson's correlation coefficient. The hydrodynamic size is negatively correlated with the absolute value of zeta potential, and positively correlated with the ionic strength. In the NaCl solution, the charge screening effect is responsible for the aggregation. In the CaCl{sub 2} solution, the charge screening effect is dominant mechanism for aggregation at a low salt concentration. In contrast, the interaction between Ca{sup 2+} ions and the specific functional group plays a significant role at a high salt concentration. The adsorption efficiency of humic acid decreases with an increase in the pH value, whereas increases with an increase in the ionic strength. The adsorption efficiency is positively correlated with the zeta potential. The statistical analysis methods and the results have implications in assessment of potential environmental risks posed by engineered nanoparticles.

  17. Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces

    Science.gov (United States)

    Giresse Tetsassi Feugmo, Conrard; Champagne, Benoît; Caudano, Yves; Cecchet, Francesca; Chabal, Yves J.; Liégeois, Vincent

    2012-03-01

    In this work, we investigate the adsorption process of two carboxylic acids (stearic and undecylenic) on a H-Si(111) surface via the calculation of structural and energy changes as well as the simulation of their IR and Raman spectra. The two molecules adsorb differently at the surface since the stearic acid simply physisorbs while the undecylenic acid undergoes a chemical reaction with the hydrogen atoms of the surface. This difference is observed in the change of geometry during the adsorption. Indeed, the chemisorption of the undecylenic acid has a bigger impact on the structure than the physisorption of the stearic acid. Consistently, the former is also characterized by a larger value of adsorption energy and a smaller value of the tilting angle with respect to the normal plane. For both the IR and Raman signatures, the spectra of both molecules adsorbed at the surface are in a first approximation the superposition of the spectra of the Si cluster and of the carboxylic acid considered individually. The main deviation from this simple observation is the peak of the stretching Si-H (ν(Si-H)) mode, which is split into two peaks upon adsorption. As expected, the splitting is bigger for the chemisorption than the physisorption. The modes corresponding to atomic displacements close to the adsorption site display a frequency upshift by a dozen wavenumbers. One can also see the disappearance of the peaks associated with the C=C double bond when the undecylenic acid chemisorbs at the surface. The Raman and IR spectra are complementary and one can observe here that the most active Raman modes are generally IR inactive. Two exceptions to this are the two ν(Si-H) modes which are active in both spectroscopies. Finally, we compare our simulated spectra with some experimental measurements and we find an overall good agreement.

  18. Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces

    International Nuclear Information System (INIS)

    Tetsassi Feugmo, Conrard Giresse; Champagne, Benoît; Liégeois, Vincent; Caudano, Yves; Cecchet, Francesca; Chabal, Yves J

    2012-01-01

    In this work, we investigate the adsorption process of two carboxylic acids (stearic and undecylenic) on a H-Si(111) surface via the calculation of structural and energy changes as well as the simulation of their IR and Raman spectra. The two molecules adsorb differently at the surface since the stearic acid simply physisorbs while the undecylenic acid undergoes a chemical reaction with the hydrogen atoms of the surface. This difference is observed in the change of geometry during the adsorption. Indeed, the chemisorption of the undecylenic acid has a bigger impact on the structure than the physisorption of the stearic acid. Consistently, the former is also characterized by a larger value of adsorption energy and a smaller value of the tilting angle with respect to the normal plane. For both the IR and Raman signatures, the spectra of both molecules adsorbed at the surface are in a first approximation the superposition of the spectra of the Si cluster and of the carboxylic acid considered individually. The main deviation from this simple observation is the peak of the stretching Si-H (ν(Si-H)) mode, which is split into two peaks upon adsorption. As expected, the splitting is bigger for the chemisorption than the physisorption. The modes corresponding to atomic displacements close to the adsorption site display a frequency upshift by a dozen wavenumbers. One can also see the disappearance of the peaks associated with the C=C double bond when the undecylenic acid chemisorbs at the surface. The Raman and IR spectra are complementary and one can observe here that the most active Raman modes are generally IR inactive. Two exceptions to this are the two ν(Si-H) modes which are active in both spectroscopies. Finally, we compare our simulated spectra with some experimental measurements and we find an overall good agreement. (paper)

  19. Mycoplasma hyopneumoniae and Mycoplasma flocculare differential domains from orthologous surface proteins induce distinct cellular immune responses in mice.

    Science.gov (United States)

    Leal, Fernanda Munhoz Dos Anjos; Virginio, Veridiana Gomes; Martello, Carolina Lumertz; Paes, Jéssica Andrade; Borges, Thiago J; Jaeger, Natália; Bonorino, Cristina; Ferreira, Henrique Bunselmeyer

    2016-07-15

    Mycoplasma hyopneumoniae and Mycoplasma flocculare are two genetically close species found in the swine respiratory tract. Despite their similarities, while M. hyopneumoniae is the causative agent of porcine enzootic pneumonia, M. flocculare is a commensal bacterium. Genomic and transcriptional comparative analyses so far failed to explain the difference in pathogenicity between these two species. We then hypothesized that such difference might be, at least in part, explained by amino acid sequence and immunological or functional differences between ortholog surface proteins. In line with that, it was verified that approximately 85% of the ortholog surface proteins from M. hyopneumoniae 7448 and M. flocculare present one or more differential domains. To experimentally assess possible immunological implications of this kind of difference, the extracellular differential domains from one pair of orthologous surface proteins (MHP7448_0612, from M. hyopneumoniae, and MF_00357, from M. flocculare) were expressed in E. coli and used to immunize mice. The recombinant polypeptides (rMHP61267-169 and rMF35767-196, respectively) induced distinct cellular immune responses. While, rMHP61267-169 induced both Th1 and Th2 responses, rMF35767-196 induced just an early pro-inflammatory response. These results indicate that immunological properties determined by differential domains in orthologous surface protein might play a role in pathogenicity, contributing to elicit specific and differential immune responses against each species. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Prediction of material removal rate and surface roughness for wire electrical discharge machining of nickel using response surface methodology

    Directory of Open Access Journals (Sweden)

    Thangam Chinnadurai

    2016-12-01

    Full Text Available This study focuses on investigating the effects of process parameters, namely, Peak current (Ip, Pulse on time (Ton, Pulse off time (Toff, Water pressure (Wp, Wire feed rate (Wf, Wire tension (Wt, Servo voltage (Sv and Servo feed setting (Sfs, on the Material Removal Rate (MRR and Surface Roughness (SR for Wire electrical discharge machining (Wire-EDM of nickel using Taguchi method. Response Surface Methodology (RSM is adopted to evolve mathematical relationships between the wire cutting process parameters and the output variables of the weld joint to determine the welding input parameters that lead to the desired optimal wire cutting quality. Besides, using response surface plots, the interaction effects of process parameters on the responses are analyzed and discussed. The statistical software Mini-tab is used to establish the design and to obtain the regression equations. The developed mathematical models are tested by analysis-of-variance (ANOVA method to check their appropriateness and suitability. Finally, a comparison is made between measured and calculated results, which are in good agreement. This indicates that the developed models can predict the responses accurately and precisely within the limits of cutting parameter being used.

  1. Prediction of material removal rate and surface roughness for wire electrical discharge machining of nickel using response surface methodology

    International Nuclear Information System (INIS)

    Chinnadurai, T.; Vendan, S.A.

    2016-01-01

    This study focuses on investigating the effects of process parameters, namely, Peak current (Ip), Pulse on time (Ton), Pulse off time (Toff), Water pressure (Wp), Wire feed rate (Wf), Wire tension (Wt), Servo voltage (Sv) and Servo feed setting (Sfs), on the Material Removal Rate (MRR) and Surface Roughness (SR) for Wire electrical discharge machining (Wire-EDM) of nickel using Taguchi method. Response Surface Methodology (RSM) is adopted to evolve mathematical relationships between the wire cutting process parameters and the output variables of the weld joint to determine the welding input parameters that lead to the desired optimal wire cutting quality. Besides, using response surface plots, the interaction effects of process parameters on the responses are analyzed and discussed. The statistical software Mini-tab is used to establish the design and to obtain the regression equations. The developed mathematical models are tested by analysis-of-variance (ANOVA) method to check their appropriateness and suitability. Finally, a comparison is made between measured and calculated results, which are in good agreement. This indicates that the developed models can predict the responses accurately and precisely within the limits of cutting parameter being used. (Author)

  2. Prediction of material removal rate and surface roughness for wire electrical discharge machining of nickel using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Chinnadurai, T.; Vendan, S.A.

    2016-07-01

    This study focuses on investigating the effects of process parameters, namely, Peak current (Ip), Pulse on time (Ton), Pulse off time (Toff), Water pressure (Wp), Wire feed rate (Wf), Wire tension (Wt), Servo voltage (Sv) and Servo feed setting (Sfs), on the Material Removal Rate (MRR) and Surface Roughness (SR) for Wire electrical discharge machining (Wire-EDM) of nickel using Taguchi method. Response Surface Methodology (RSM) is adopted to evolve mathematical relationships between the wire cutting process parameters and the output variables of the weld joint to determine the welding input parameters that lead to the desired optimal wire cutting quality. Besides, using response surface plots, the interaction effects of process parameters on the responses are analyzed and discussed. The statistical software Mini-tab is used to establish the design and to obtain the regression equations. The developed mathematical models are tested by analysis-of-variance (ANOVA) method to check their appropriateness and suitability. Finally, a comparison is made between measured and calculated results, which are in good agreement. This indicates that the developed models can predict the responses accurately and precisely within the limits of cutting parameter being used. (Author)

  3. Functionality of porous silicon particles: Surface modification for biomedical applications

    International Nuclear Information System (INIS)

    Gallach, D.; Recio Sanchez, G.; Munoz Noval, A.; Manso Silvan, M.; Ceccone, G.; Martin Palma, R.J.; Torres Costa, V.; Martinez Duart, J.M.

    2010-01-01

    Porous silicon-based particles (PSps) with tailored physical and biological properties have recently attracted great attention given their biomedical potential. Within this context, the objective of the present work is to optimize the experimental parameters for the formation of biofunctional mesoporous PSps. Their functionality has been studied on the one hand by analyzing the fluorescence characteristics, such as tunable narrow band emission and fluorescence aging for PSps with different molecular capping. With regard to the biofunctional characteristics, two different molecular end-capping processes have been assayed: antifouling polyethylene glycol (PEG) and polar binding amino silanes (APTS), which were evaluated by X-ray photoelectron spectroscopy (XPS). Both PEG and APTS binding to the particles could be confirmed from the analysis of Si 2p and C 1s XPS core level spectra. The finding that these PSp-molecule conjugates allow the reduction of fluorescence degradation with time in solution is of interest for the development of cellular or tissue markers. From the morphological point of view, PEG termination is of special interest allowing the PSps after an ultrasonic treatment to get spherical shapes in the micron scale. The functionality as solid state dyes is preliminarily evaluated by direct fluorescence imaging.

  4. Functionality of porous silicon particles: Surface modification for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Gallach, D.; Recio Sanchez, G.; Munoz Noval, A. [Departamento de Fisica Aplicada y Departamento de Biologia Molecular, Facultad de Ciencias, Cantoblanco, 28049 Madrid (Spain); Centro de Investigaciones Biomedicas en Red, Biomateriales, Bioingenieria y Nanomedicina (CIBERbbn) (Spain); Manso Silvan, M., E-mail: miguel.manso@uam.es [Departamento de Fisica Aplicada y Departamento de Biologia Molecular, Facultad de Ciencias, Cantoblanco, 28049 Madrid (Spain); Centro de Investigaciones Biomedicas en Red, Biomateriales, Bioingenieria y Nanomedicina (CIBERbbn) (Spain); Ceccone, G. [Institute for Health and Consumer Protection, European Commission, 21020 Ispra (Italy); Martin Palma, R.J.; Torres Costa, V.; Martinez Duart, J.M. [Departamento de Fisica Aplicada y Departamento de Biologia Molecular, Facultad de Ciencias, Cantoblanco, 28049 Madrid (Spain); Centro de Investigaciones Biomedicas en Red, Biomateriales, Bioingenieria y Nanomedicina (CIBERbbn) (Spain)

    2010-05-25

    Porous silicon-based particles (PSps) with tailored physical and biological properties have recently attracted great attention given their biomedical potential. Within this context, the objective of the present work is to optimize the experimental parameters for the formation of biofunctional mesoporous PSps. Their functionality has been studied on the one hand by analyzing the fluorescence characteristics, such as tunable narrow band emission and fluorescence aging for PSps with different molecular capping. With regard to the biofunctional characteristics, two different molecular end-capping processes have been assayed: antifouling polyethylene glycol (PEG) and polar binding amino silanes (APTS), which were evaluated by X-ray photoelectron spectroscopy (XPS). Both PEG and APTS binding to the particles could be confirmed from the analysis of Si 2p and C 1s XPS core level spectra. The finding that these PSp-molecule conjugates allow the reduction of fluorescence degradation with time in solution is of interest for the development of cellular or tissue markers. From the morphological point of view, PEG termination is of special interest allowing the PSps after an ultrasonic treatment to get spherical shapes in the micron scale. The functionality as solid state dyes is preliminarily evaluated by direct fluorescence imaging.

  5. Using the lambda function to evaluate probe measurements of charged dielectric surfaces

    DEFF Research Database (Denmark)

    Rerup, T. O.; Crichton, George C; McAllister, Iain Wilson

    1996-01-01

    The use of Pedersen's λ function to evaluate electrostatic probe measurements of charged dielectric surfaces is demonstrated. With a knowledge of the probe λ function, the procedure by which this function is employed is developed, and thereafter applied to a set of experimental measurements avail...

  6. Differential surface phenotype and context-dependent reactivity of functionally diverse NKT cells.

    Science.gov (United States)

    Cameron, Garth; Godfrey, Dale I

    2018-03-05

    Natural Killer T (NKT) cells are a functionally diverse population that recognizes lipid-based antigens in association with the antigen-presenting molecule CD1d. Here, we define a technique to separate the functionally distinct thymic NKT1, NKT2 and NKT17 cell subsets by their surface expression of CD278 (ICOS) and the activation-associated glycoform of CD43, enabling the investigation of subset-specific effector-functions. We report that all three subsets express the transcription factor GATA-3 and the potential to produce IL-4 and IL-10 following activation. This questions the notion that NKT2 cells are the predominant source of IL-4 within the NKT cell pool, and suggests that IL-10-production may be more indicative of NKT cell plasticity than the existence of a distinct regulatory lineage or subset. We also show that many NKT17 cells are CD4 + and are biased toward Vβ8.3 TCR gene usage. Lastly, we demonstrate that the toll-like receptor (TLR) ligand lipopolysaccharide (LPS) can induce a NKT17 cell-biased response, even in the absence of exogenous antigen, and that combining LPS with α-GalCer resulted in enhanced IL-17A-production, and reduced levels of the immunosuppressive cytokine IL-10. This study provides a novel means to examine the context-dependent reactivity of the functionally heterogeneous NKT cell population and provides important new insight into the functional biology of these subsets. © 2018 Australasian Society for Immunology Inc.

  7. Stable functionalization of germanium surface and its application in biomolecules immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Qi [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); University of Chinese Academy of Sciences, No.19A, Yuquan Road, Beijing 100049 (China); Xu, Baojian [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); Ye, Lin [Sate Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); University of Chinese Academy of Sciences, No.19A, Yuquan Road, Beijing 100049 (China); Tang, Teng; Huang, Shanluo; Du, Xiaowei [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); University of Chinese Academy of Sciences, No.19A, Yuquan Road, Beijing 100049 (China); Bian, Xiaojun; Zhang, Jishen [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); Di, Zengfeng, E-mail: zfdi@mail.sim.ac.cn [Sate Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); Jin, Qinghui [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); Zhao, Jianlong, E-mail: jlzhao@mail.sim.ac.cn [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China)

    2014-10-15

    Highlights: • An effective method to immobilize biomolecules on the functionalized Ge surface. • The surface of Ge was functionalized with 11-Mercaptoundecanoic acid (11-MUA). • Stable and uniform SAMs was obtained on Ge surface after 11-MUA treatment. • The functionalized Ge was employed as substrate for protein immobilization. • Paving the way of Ge for further applications in bioelectronics field. - Abstract: As a typical semiconductor material, germanium (Ge) has the potential to be utilized in microelectronics and bioelectronics. Herein, we present a simple and effective method to immobilize biomolecules on the surface of functionalized Ge. The surface oxide of Ge was removed with the pretreatment of hydrochloric acid and the Cl-terminated Ge reacted with 11-Mercaptoundecanoic acid (11-MUA). The surface of Ge was coated with 11-MUA self-assembled monolayers (SAMs) due to the bonding reaction between the sulfhydryl group of 11-MUA and Cl-terminated Ge. Furthermore, typical biomolecule, a green fluorescent protein was chosen to be immobilized on the surface of the functionalized Ge. Contact angle analysis, atomic force microscopy and X-ray photoelectron spectroscopy were used to study the characteristics including wettability, stability, roughness and component of the functionalized Ge, respectively. Fluorescence microscopy was utilized to indicate the efficiency of protein immobilization on the surface of the functionalized Ge. With these studies, stable and uniform functionalized monolayer was obtained on the surface of Ge after 11-MUA treatment and the functionalized Ge was effectively applied in protein immobilization. Furthermore, this study may pave the way for further applications such as the integration of bioelectronics and biosensors with the attractive semiconductor material-Ge in future work.

  8. Surface functionalization by fine ultraviolet-patterning of nanometer-thick liquid lubricant films

    International Nuclear Information System (INIS)

    Lu, Renguo; Zhang, Hedong; Komada, Suguru; Mitsuya, Yasunaga; Fukuzawa, Kenji; Itoh, Shintaro

    2014-01-01

    Highlights: • We present fine UV-patterning of nm-thick liquid films for surface functionalization. • The patterned films exhibit both a morphological pattern and a functional pattern of different surface properties. • The finest pattern linewidth was 0.5 μm. • Fine patterning is crucial for improving surface and tribological properties. - Abstract: For micro/nanoscale devices, surface functionalization is essential to achieve function and performance superior to those that originate from the inherent bulk material properties. As a method of surface functionalization, we dip-coated nanometer-thick liquid lubricant films onto solid surfaces and then patterned the lubricant films with ultraviolet (UV) irradiation through a photomask. Surface topography, adhesion, and friction measurements demonstrated that the patterned films feature a concave–convex thickness distribution with thicker lubricant in the irradiated regions and a functional distribution with lower adhesion and friction in the irradiated convex regions. The pattern linewidth ranged from 100 to as fine as 0.5 μm. The surface functionalization effect of UV-patterning was investigated by measuring the water contact angles, surface energies, friction forces, and depletion of the patterned, as-dipped, and full UV-irradiated lubricant films. The full UV-irradiated lubricant film was hydrophobic with a water contact angle of 102.1°, and had lower surface energy, friction, and depletion than the as-dipped film, which was hydrophilic with a water contact angle of 80.7°. This demonstrates that UV irradiation substantially improves the surface and tribological properties of the nanometer-thick liquid lubricant films. The UV-patterned lubricant films exhibited superior surface and tribological properties than the as-dipped film. The water contact angle increased and the surface energy, friction, and depletion decreased as the pattern linewidth decreased. In particular, the 0.5-μm patterned lubricant

  9. Antiproliferative activity of Curcuma phaeocaulis Valeton extract using ultrasonic assistance and response surface methodology.

    Science.gov (United States)

    Wang, Xiaoqin; Jiang, Ying; Hu, Daode

    2017-01-02

    The objective of the study was to optimize the ultrasonic-assisted extraction of curdione, furanodienone, curcumol, and germacrone from Curcuma phaeocaulis Valeton (Val.) and investigate the antiproliferative activity of the extract. Under the suitable high-performance liquid chromatography condition, the calibration curves for these four tested compounds showed high levels of linearity and the recoveries of these four compounds were between 97.9 and 104.3%. Response surface methodology (RSM) combining central composite design and desirability function (DF) was used to define optimal extraction parameters. The results of RSM and DF revealed that the optimum conditions were obtained as 8 mL g -1 for liquid-solid ratio, 70% ethanol concentration, and 20 min of ultrasonic time. It was found that the surface structures of the sonicated herbal materials were fluffy and irregular. The C. phaeocaulis Val. extract significantly inhibited the proliferation of RKO and HT-29 cells in vitro. The results reveal that the RSM can be effectively used for optimizing the ultrasonic-assisted extraction of bioactive components from C. phaeocaulis Val. for antiproliferative activity.

  10. Surface enhanced infrared absorption spectroscopy for graphene functionalization on copper

    Czech Academy of Sciences Publication Activity Database

    Matulková, I.; Kovaříček, Petr; Šlouf, Miroslav; Němec, I.; Kalbáč, Martin

    2017-01-01

    Roč. 124, NOV 2017 (2017), s. 250-255 ISSN 0008-6223 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk LL1301; GA MŠk(CZ) LM2015073 Grant - others:AVČR PPPLZ(CZ) L200401551; GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821 Institutional support: RVO:61388955 ; RVO:61389013 Keywords : chemical-vapor-deposition * diazonium salts * raman-spectroscopy * covalent functionalization * seira spectroscopy * grown graphene Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Physical chemistry; Polymer science (UMCH-V) Impact factor: 6.337, year: 2016

  11. Grafting of phosphorylcholine functional groups on polycarbonate urethane surface for resisting platelet adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bin [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@hotmail.com [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China); Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Lu, Jian; Zhang, Li; Zhao, Miao; Shi, Changcan; Khan, Musammir [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Guo, Jintang [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China)

    2013-07-01

    In order to improve the resistance of platelet adhesion on material surface, 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted onto polycarbonate urethane (PCU) surface via Michael reaction to create biomimetic structure. After introducing primary amine groups via coupling tris(2-aminoethyl)amine (TAEA) onto the polymer surface, the double bond of MPC reacted with the amino group to obtain MPC modified PCU. The modified surface was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results verified that MPC was grafted onto PCU surface by Michael reaction method. The MPC grafted PCU surface had a low water contact angle and a high water uptake. This means that the hydrophilic PC functional groups improved the surface hydrophilicity significantly. In addition, surface morphology of MPC grafted PCU film was imaged by atomic force microscope (AFM). The results showed that the grafted surface was rougher than the blank PCU surface. In addition, platelet adhesion study was evaluated by scanning electron microscopy (SEM) observation. The PCU films after treated with platelet-rich plasma demonstrated that much fewer platelets adhered to the MPC-grafted PCU surface than to the blank PCU surface. The antithrombogenicity of the MPC-grafted PCU surface was determined by the activated partial thromboplastin time (APTT). The result suggested that the MPC modified PCU may have potential application as biomaterials in blood-contacting and some subcutaneously implanted devices. - Highlights: • MPC was successfully grafted onto polycarbonate urethane surface via Michael reaction. • High concentration of PC functional groups on the surface via TAEA molecule • Biomimetic surface modification • The modified surface showed high hydrophilicity and anti-platelet adhesion.

  12. Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery

    International Nuclear Information System (INIS)

    Behzadi, Abed; Mohammadi, Aliasghar

    2016-01-01

    Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at various quantities, and their ability to modulate oil–water interface properties and oil recovery is examined. Oil–water interfacial tension and water surface tension are decreased by 50 % in the presence of silica nanoparticles coated with both agents. Measuring oil-drop contact angle on oil-wetted glass slides and carbonate rock sections, after aging in various surface-modified silica nanofluids, indicates that the wettability of various oil-wetted surfaces is modified from strongly oil-wet to water-wet. Flooding nanofluids to glass micro-models and pore-level investigations demonstrate that surface modification of silica nanoparticles, specially, with both hydrophilic and hydrophobic agents improves considerably their performance in increasing oil recovery and wettability alteration.

  13. Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Behzadi, Abed; Mohammadi, Aliasghar, E-mail: amohammadi@sharif.edu [Sharif University of Technology, Department of Chemical and Petroleum Engineering (Iran, Islamic Republic of)

    2016-09-15

    Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at various quantities, and their ability to modulate oil–water interface properties and oil recovery is examined. Oil–water interfacial tension and water surface tension are decreased by 50 % in the presence of silica nanoparticles coated with both agents. Measuring oil-drop contact angle on oil-wetted glass slides and carbonate rock sections, after aging in various surface-modified silica nanofluids, indicates that the wettability of various oil-wetted surfaces is modified from strongly oil-wet to water-wet. Flooding nanofluids to glass micro-models and pore-level investigations demonstrate that surface modification of silica nanoparticles, specially, with both hydrophilic and hydrophobic agents improves considerably their performance in increasing oil recovery and wettability alteration.

  14. Understanding of the correlation between work function and surface morphology of metals and alloys

    International Nuclear Information System (INIS)

    Xue, Mingshan; Wang, Wenfeng; Wang, Fajun; Ou, Junfei; Li, Changquan; Li, Wen

    2013-01-01

    Highlights: •The inherent correlation between the work function and surface morphology was focused on. •The change of the work function of metals and alloys as a function of surface roughness was investigated by scanning Kelvin probe. •The lightning rod effect was used to describe the electron transport at a rough surface. -- Abstract: The relationships between material behaviors and its structures are extremely complicated, and the understanding of these relationships is of much significance for revealing the physical, chemical and mechanical properties of various materials. In this study, the change of the work function (WF) of metals and alloys as a function of surface roughness was investigated by scanning Kelvin probe, with the aim of understanding the inherent correlation between the WF and surface morphology using a simple and intuitive way. It was demonstrated that at the rough surface of Cu and Ag, the sharp micro/nanostructures induced a lower WF, just as the lightning rod effect providing a direct and fast path for electron transport. While for Al and Mg alloys, the rough surface resulted in an increase of the WF owing to the effect of surface oxide layers, just as the anti-lightning rod effect providing a protected layer to confine the electron transport

  15. Lowering the density of electronic defects on organic-functionalized Si(100) surfaces

    International Nuclear Information System (INIS)

    Peng, Weina; DeBenedetti, William J. I.; Kim, Seonjae; Chabal, Yves J.; Hines, Melissa A.

    2014-01-01

    The electrical quality of functionalized, oxide-free silicon surfaces is critical for chemical sensing, photovoltaics, and molecular electronics applications. In contrast to Si/SiO 2 interfaces, the density of interface states (D it ) cannot be reduced by high temperature annealing because organic layers decompose above 300 °C. While a reasonable D it is achieved on functionalized atomically flat Si(111) surfaces, it has been challenging to develop successful chemical treatments for the technologically relevant Si(100) surfaces. We demonstrate here that recent advances in the chemical preparation of quasi-atomically-flat, H-terminated Si(100) surfaces lead to a marked suppression of electronic states of functionalized surfaces. Using a non-invasive conductance-voltage method to study functionalized Si(100) surfaces with varying roughness, a D it as low as 2.5 × 10 11  cm −2 eV −1 is obtained for the quasi-atomically-flat surfaces, in contrast to >7 × 10 11  cm −2 eV −1 on atomically rough Si(100) surfaces. The interfacial quality of the organic/quasi-atomically-flat Si(100) interface is very close to that obtained on organic/atomically flat Si(111) surfaces, opening the door to applications previously thought to be restricted to Si(111)

  16. Functionality of novel black silicon based nanostructured surfaces studied by TOF SIMS

    DEFF Research Database (Denmark)

    Talian, Ivan; Aranyosiova, M.; Orinak, A.

    2010-01-01

    A functionality of the novel black silicon based nanostructured surfaces (BS 2) with different metal surface modifications was tested by time-of-flight secondary ion mass spectrometry (TOF SIMS). Mainly two surface functions were studied: analytical signal enhancement and analyte pre-ionization e......A functionality of the novel black silicon based nanostructured surfaces (BS 2) with different metal surface modifications was tested by time-of-flight secondary ion mass spectrometry (TOF SIMS). Mainly two surface functions were studied: analytical signal enhancement and analyte pre......-ionization effect in SIMS due to nanostructure type and the assistance of the noble metal surface coating (Ag or Au) for secondary ion formation. As a testing analyte a Rhodamine 6G was applied. Bi+ has been used as SIMS primary ions. It was found out that SIMS signal enhancement of the analyte significantly...... depends on Ag layer thickness and measured ion mode (negative, positive). The best SIMS signal enhancement was obtained at BS2 surface coated with 400 nm of Ag layer. SIMS fragmentation schemes were developed for a model analyte deposited onto a silver and gold surface. Significant differences in pre...

  17. Density functional theory of simple polymers in a slit pore. III. Surface tension

    International Nuclear Information System (INIS)

    Hooper, Justin B.; McCoy, John D.; Curro, John G.; Swol, Frank van

    2000-01-01

    In a previous study of tangent hard-site chains near a surface, the inhomogeneous density profiles were found through density functional theory. In the current study, the surface tensions of these systems are found from the results of the previous study through a thermodynamic integration. The calculated surface tensions are then compared to those found directly through computer simulation. Both the surface tension and surface excess for polymeric systems are shown to differ qualitatively from those of atomic systems, although certain similarities are seen at high densities. (c) 2000 American Institute of Physics

  18. Application of Response Surface Methodology for the Technological Improvement of Solid Lipid Nanoparticles.

    Science.gov (United States)

    Dal Pizzol, Carine; O'Reilly, Andre; Winter, Evelyn; Sonaglio, Diva; de Campos, Angela Machado; Creczynski-Pasa, Tânia Beatriz

    2016-02-01

    Solid lipid nanoparticles (SLN) are colloidal particles consisting of a matrix composed of solid (at room and body temperatures) lipids dispersed in aqueous emulsifier solution. During manufacture, their physicochemical properties may be affected by several formulation parameters, such as type and concentration of lipid, proportion of emulsifiers and amount of solvent. Thus, the aim of this work was to study the influence of these variables on the preparation of SLN. A D-optimal Response Surface Methodology design was used to establish a mathematical model for the optimization of SLN. A total of 30 SLN formulations were prepared using the ultrasound method, and then characterized on the basis of their physicochemical properties, including particle size, polydispersity index (PI) and Zeta Potential (s). Particle sizes ranged between 107 and 240 nm. All SLN formulations showed negative sigma and PI values below 0.28. Prediction of the optimal conditions was performed using the desirability function targeting the reduction of all responses. The optimized SLN formulation showed similar theoretical and experimental values, confirming the sturdiness and predictive ability of the mathematical model for SLN optimization.

  19. Optimization of a novel improver gel formulation for Barbari flat bread using response surface methodology.

    Science.gov (United States)

    Pourfarzad, Amir; Haddad Khodaparast, Mohammad Hossein; Karimi, Mehdi; Mortazavi, Seyed Ali

    2014-10-01

    Nowadays, the use of bread improvers has become an essential part of improving the production methods and quality of bakery products. In the present study, the Response Surface Methodology (RSM) was used to determine the optimum improver gel formulation which gave the best quality, shelf life, sensory and image properties for Barbari flat bread. Sodium stearoyl-2-lactylate (SSL), diacetyl tartaric acid esters of monoglyceride (DATEM) and propylene glycol (PG) were constituents of the gel and considered in this study. A second-order polynomial model was fitted to each response and the regression coefficients were determined using least square method. The optimum gel formulation was found to be 0.49 % of SSL, 0.36 % of DATEM and 0.5 % of PG when desirability function method was applied. There was a good agreement between the experimental data and their predicted counterparts. Results showed that the RSM, image processing and texture analysis are useful tools to investigate, approximate and predict a large number of bread properties.

  20. Forest ecotone response to climate change: sensitivity to temperature response functional forms

    Energy Technology Data Exchange (ETDEWEB)

    Loehle, C. [National Council for Air and Stream Improvement, Naperville, IL (United States)

    2000-10-01

    Past simulation studies have been in general agreement that climatic change could have adverse effects on forests, including geographic range shrinkages, conversion to grassland, and catastrophic forest decline or dieback. Some other recent studies, however, concluded that this agreement is generally based on parabolic temperature response rather than functional responses or data, and may therefore exaggerate dieback effects. This paper proposes a new model of temperature response that is based on a trade-off between cold tolerance and growth rate. In this model, the growth rate increases at first, and then levels off with increasing growing degree-days. Species from more southern regions have a higher minimum temperature and a faster maximum height growth rate. It is argued that faster growth rates of southern types lead to their competitive superiority in warmer environments and that such temperature response should produce less dieback and slower rates of change than the more common parabolic response model. Theoretical justification of this model is provided, followed by application of the model to a simulated ecotone under a warming scenario. Results of the study based on the proposed asymptotic model showed no dieback and only a gradual ecotone movement north, suggesting that ecotone shifts will, in fact, take many hundreds to thousands of years, with the result that species will not face the risk of extinction. 56 refs., 1 tab., 8 figs.

  1. A Response Surface-Based Cost Model for Wind Farm Design

    International Nuclear Information System (INIS)

    Zhang Jie; Chowdhury, Souma; Messac, Achille; Castillo, Luciano

    2012-01-01

    A Response Surface-Based Wind Farm Cost (RS-WFC) model is developed for the engineering planning of wind farms. The RS-WFC model is developed using Extended Radial Basis Functions (E-RBF) for onshore wind farms in the U.S. This model is then used to explore the influences of different design and economic parameters, including number of turbines, rotor diameter and labor cost, on the cost of a wind farm. The RS-WFC model is composed of three components that estimate the effects of engineering and economic factors on (i) the installation cost, (ii) the annual Operation and Maintenance (O and M) cost, and (iii) the total annual cost of a wind farm. The accuracy of the cost model is favorably established through comparison with pertinent commercial data. The final RS-WFC model provided interesting insights into cost variation with respect to critical engineering and economic parameters. In addition, a newly developed analytical wind farm engineering model is used to determine the power generated by the farm, and the subsequent Cost of Energy (COE). This COE is optimized for a unidirectional uniform “incoming wind speed” scenario using Particle Swarm Optimization (PSO). We found that the COE could be appreciably minimized through layout optimization, thereby yielding significant cost savings. - Highlights: ► We present a Response Surface-Based Wind Farm Cost (RS-WFC) model for wind farm design. ► The model could estimate installation cost, Operation and Maintenance cost, and total annual cost of a wind farm. ► The Cost of Energy is optimized using Particle Swarm Optimization. ► Layout optimization could yield significant cost savings.

  2. Functional models for commutative systems of linear operators and de Branges spaces on a Riemann surface

    International Nuclear Information System (INIS)

    Zolotarev, Vladimir A

    2009-01-01

    Functional models are constructed for commutative systems {A 1 ,A 2 } of bounded linear non-self-adjoint operators which do not contain dissipative operators (which means that ξ 1 A 1 +ξ 2 A 2 is not a dissipative operator for any ξ 1 , ξ 2 element of R). A significant role is played here by the de Branges transform and the function classes occurring in this context. Classes of commutative systems of operators {A 1 ,A 2 } for which such a construction is possible are distinguished. Realizations of functional models in special spaces of meromorphic functions on Riemann surfaces are found, which lead to reasonable analogues of de Branges spaces on these Riemann surfaces. It turns out that the functions E(p) and E-tilde(p) determining the order of growth in de Branges spaces on Riemann surfaces coincide with the well-known Baker-Akhiezer functions. Bibliography: 11 titles.

  3. Local changes of work function near rough features on Cu surfaces operated under high external electric field

    Energy Technology Data Exchange (ETDEWEB)

    Djurabekova, Flyura, E-mail: flyura.djurabekova@helsinki.fi; Ruzibaev, Avaz; Parviainen, Stefan [Helsinki Institute of Physics and Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 Helsinki (Finland); Holmström, Eero [Department of Physics, University of Helsinki, P.O. Box 64, FIN-00014 Helsinki (Finland); Department of Earth Sciences, Faculty of Maths and Physical Sciences, UCL Earth Sciences, Gower Street, London WC1E 6BT (United Kingdom); Hakala, Mikko [Department of Physics, University of Helsinki, P.O. Box 64, FIN-00014 Helsinki (Finland)

    2013-12-28

    Metal surfaces operated under high electric fields produce sparks even if they are held in ultra high vacuum. In spite of extensive research on the topic of vacuum arcs, the mystery of vacuum arc origin still remains unresolved. The indications that the sparking rates depend on the material motivate the research on surface response to extremely high external electric fields. In this work by means of density-functional theory calculations we analyze the redistribution of electron density on (100) Cu surfaces due to self-adatoms and in presence of high electric fields from −1 V/nm up to −2 V/nm (−1 to −2 GV/m, respectively). We also calculate the partial charge induced by the external field on a single adatom and a cluster of two adatoms in order to obtain reliable information on charge redistribution on surface atoms, which can serve as a benchmarking quantity for the assessment of the electric field effects on metal surfaces by means of molecular dynamics simulations. Furthermore, we investigate the modifications of work function around rough surface features, such as step edges and self-adatoms.

  4. Surface Modified Multifunctional and Stimuli Responsive Nanoparticles for Drug Targeting: Current Status and Uses

    Directory of Open Access Journals (Sweden)

    Panoraia I. Siafaka

    2016-08-01

    Full Text Available Nanocarriers, due to their unique features, are of increased interest among researchers working with pharmaceutical formulations. Polymeric nanoparticles and nanocapsules, involving non-toxic biodegradable polymers, liposomes, solid lipid nanoparticles, and inorganic–organic nanomaterials, are among the most used carriers for drugs for a broad spectrum of targeted diseases. In fact, oral, injectable, transdermal-dermal and ocular formulations mainly consist of the aforementioned nanomaterials demonstrating promising characteristics such as long circulation, specific targeting, high drug loading capacity, enhanced intracellular penetration, and so on. Over the last decade, huge advances in the development of novel, safer and less toxic nanocarriers with amended properties have been made. In addition, multifunctional nanocarriers combining chemical substances, vitamins and peptides via coupling chemistry, inorganic particles coated by biocompatible materials seem to play a key role considering that functionalization can enhance characteristics such as biocompatibility, targetability, environmental friendliness, and intracellular penetration while also have limited side effects. This review aims to summarize the “state of the art” of drug delivery carriers in nanosize, paying attention to their surface functionalization with ligands and other small or polymeric compounds so as to upgrade active and passive targeting, different release patterns as well as cell targeting and stimuli responsibility. Lastly, future aspects and potential uses of nanoparticulated drug systems are outlined.

  5. Response surface optimization of the medium components for the production of biosurfactants by probiotic bacteria

    NARCIS (Netherlands)

    Rodrigues, L; Teixeira, J; Oliveira, R; van der Mei, HC

    Optimization of the medium for biosurfactants production by probiotic bacteria (Lactococcus lactis 53 and Streptococcus thermophilus A) was carried out using response surface methodology. Both biosurfactants were proved to be growth-associated, thus the desired response selected for the optimization

  6. Electromechanical response of a curved piezoelectric nanobeam with the consideration of surface effects

    International Nuclear Information System (INIS)

    Yan Zhi; Jiang Liying

    2011-01-01

    This work investigates the electromechanical response of a curved piezoelectric nanobeam with the consideration of surface effects through the surface-layer-based model and the generalized Young-Laplace equations. For nanoscale piezoelectric structures, the surface effects also include surface piezoelectricity in addition to the residual surface stress and surface elasticity for elastic nanomaterials. A Euler-Bernoulli curved beam theory is used to get the explicit solutions for the electroelastic fields of a curved cantilever beam when subjected to mechanical and electrical loads. In order to apply the appropriate boundary conditions on the beam, effective axial force, shear force and moment are derived. The results indicate that the surface effects play a significant role in the electroelastic fields and the piezoelectric response of the curved piezoelectric nanobeam. It is also found that the coupling of the residual surface stress, the surface elasticity and the surface piezoelectricity may be dramatic despite that the influence of the individual one is small under some circumstances. This study is expected to be useful for design and applications of curved beam based piezoelectric nanodevices, such as the curved nanowires/nanobelts or nanorings as nanoswitches or nanoactuators for displacement control purpose.

  7. Functional Associations by Response Overlap (FARO, a functional genomics approach matching gene expression phenotypes.

    Directory of Open Access Journals (Sweden)

    Henrik Bjørn Nielsen

    2007-08-01

    Full Text Available The systematic comparison of transcriptional responses of organisms is a powerful tool in functional genomics. For example, mutants may be characterized by comparing their transcript profiles to those obtained in other experiments querying the effects on gene expression of many experimental factors including treatments, mutations and pathogen infections. Similarly, drugs may be discovered by the relationship between the transcript profiles effectuated or impacted by a candidate drug and by the target disease. The integration of such data enables systems biology to predict the interplay between experimental factors affecting a biological system. Unfortunately, direct comparisons of gene expression profiles obtained in independent, publicly available microarray experiments are typically compromised by substantial, experiment-specific biases. Here we suggest a novel yet conceptually simple approach for deriving 'Functional Association(s by Response Overlap' (FARO between microarray gene expression studies. The transcriptional response is defined by the set of differentially expressed genes independent from the magnitude or direction of the change. This approach overcomes the limited comparability between studies that is typical for methods that rely on correlation in gene expression. We apply FARO to a compendium of 242 diverse Arabidopsis microarray experimental factors, including phyto-hormones, stresses and pathogens, growth conditions/stages, tissue types and mutants. We also use FARO to confirm and further delineate the functions of Arabidopsis MAP kinase 4 in disease and stress responses. Furthermore, we find that a large, well-defined set of genes responds in opposing directions to different stress conditions and predict the effects of different stress combinations. This demonstrates the usefulness of our approach for exploiting public microarray data to derive biologically meaningful associations between experimental factors. Finally, our

  8. Investigation of pH response and photo-control of wettability on spiropyran-derivatized surfaces

    Science.gov (United States)

    Park, Choong-Do

    2009-12-01

    One promising method to control a liquid drop on a surface for microfluidic devices is to use the surface tension gradient on a photo-responsive surface by light irradiation. A photo-switchable spiropyran monolayer was prepared on smooth glass or silicon wafers via 3-aminopropylmethyldiethoxysilane linkages. The pH response of the surface-bound spiropyran was investigated by measuring contact angle as a function of pH, since the pH value of the liquids applied to a microfluidic system can vary widely. Based on the contact angle titration and UV-Vis spectroscopic data, a protonation and deprotonation mechanism of the surface-bound spiropyran was proposed. The advancing contact angles under UV and under visible light irradiation at high pH values were about 100 smaller than those at low pH values. The decrease in contact angle under UV light with decreasing pH value was assigned to the protonation of open merocyanine (MC) to MC-OH+. Meanwhile, the decrease in contact angle under visible light was attributed to the protonation of the closed spiropryan (SP), generating a mixed state of MC-OH+ in equilibrium with N-protonated SP-NH+. In order to examine the possibility of light-induced liquid drop motion on the spiropyran-derivatized smooth surfaces, the light-induced surface tension change between SP and MC was estimated using the contact angle hysteresis (CAH) and the Lifshitz---van der Waals/Acid-Base (LWAB) approaches based on the contact angle data. The average light-induced surface energy change between the two isomers under UV and visible light exposure was 1.4 mJ/m 2, implying that the small change in surface tension is not sufficient to move a liquid droplet on the surface. Liquid drop motion requires that the light-induced switching angle be greater than the contact angle hysteresis. However, the light-induced switching angle of the spiropyran-derivatized surface was significantly smaller than the hysteresis. Thus, in order to achieve liquid drop motion on the

  9. Electromagnetic and neutral-weak response functions of light nuclei

    Science.gov (United States)

    Lovato, Alessandro

    2015-10-01

    A major goal of nuclear theory is to understand the strong interaction in nuclei as it manifests itself in terms of two- and many-body forces among the nuclear constituents, the protons and neutrons, and the interactions of these constituents with external electroweak probes via one- and many-body currents. Using imaginary-time projection technique, quantum Monte Carlo allows for solving the time-independent Schrödinger equation even for Hamiltonians including highly spin-isospin dependent two- and three- body forces. I will present a recent Green's function Monte Carlo calculation of the quasi-elastic electroweak response functions in light nuclei, needed to describe electron and neutrino scattering. We found that meson-exchange two-body currents generate excess transverse strength from threshold to the quasielastic to the dip region and beyond. These results challenge the conventional picture of quasi elastic inclusive scattering as being largely dominated by single-nucleon knockout processes. These findings are of particular interest for the interpretation of neutrino oscillation signals.

  10. Two process chains for creating functional surfaces on mold for 3D geometry

    DEFF Research Database (Denmark)

    Zhang, Yang; Hansen, Hans Nørgaard; Pedersen, David Bue

    . This paper describes and compares 2 approaches for fabricating micro- structured surfaces suitable for patterning of 3D shape cavity for injection moulding. The application investigated for the research is a part of a fixture for electrodes to be implanted inside human body. It is a ring with four wings......Polymer products with functional surfaces are applied in many fields such as medical and bio technology [1][2]. It is believed that certain types of micro- or nano- structured surfaces can enhance tissue anchoring [3]. However, most technologies for the fabrication of micro-structured functional...... surfaces are still limited to flat geometries or geometries with constant curvature [4] . Typically products that need micro structuring on the surface have a three dimensional and complex geometry. There are huge demand for investigation in establishing the micro structures on the surface of a 3D mold...

  11. Optimization of CO2 Laser Cutting Process using Taguchi and Dual Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    M. Madić

    2014-09-01

    Full Text Available Selection of optimal cutting parameter settings for obtaining high cut quality in CO2 laser cutting process is of great importance. Among various analytical and experimental optimization methods, the application of Taguchi and response surface methodology is one of most commonly used for laser cutting process optimization. Although the concept of dual response surface methodology for process optimization has been used with success, till date, no experimental study has been reported in the field of laser cutting. In this paper an approach for optimization of CO2 laser cutting process using Taguchi and dual response surface methodology is presented. The goal was to determine the near optimal laser cutting parameter values in order to ensure robust condition for minimization of average surface roughness. To obtain experimental database for development of response surface models, Taguchi’s L25 orthogonal array was implemented for experimental plan. Three cutting parameters, the cutting speed (3, 4, 5, 6, 7 m/min, the laser power (0.7, 0.9, 1.1, 1.3, 1.5 kW, and the assist gas pressure (3, 4, 5, 6, 7 bar, were used in the experiment. To obtain near optimal cutting parameters settings, multi-stage Monte Carlo simulation procedure was performed on the developed response surface models.

  12. Effect of Q-switched Laser Surface Texturing of Titanium on Osteoblast Cell Response

    Science.gov (United States)

    Voisey, K. T.; Scotchford, C. A.; Martin, L.; Gill, H. S.

    Titanium and its alloys are important biomedical materials. It is known that the surface texture of implanted medical devices affects cell response. Control of cell response has the potential to enhance fixation of implants into bone and, in other applications, to prevent undesired cell adhesion. The potential use of a 100W Q-switched YAG laser miller (DMG Lasertec 60 HSC) for texturing titanium is investigated. A series of regular features with dimensions of the order of tens of micrometers are generated in the surface of titanium samples and the cell response to these features is determined. Characterisation of the laser milled features reveals features with a lengthscale of a few microns superposed on the larger scale structures, this is attributed to resolidification of molten droplets generated and propelled over the surface by individual laser pulses. The laser textured samples are exposed to osteoblast cells and it is seen that cells do respond to the features in the laser textured surfaces.

  13. Surface Acoustic Wave (SAW-Enhanced Chemical Functionalization of Gold Films

    Directory of Open Access Journals (Sweden)

    Gina Greco

    2017-10-01

    Full Text Available Surface chemical and biochemical functionalization is a fundamental process that is widely applied in many fields to add new functions, features, or capabilities to a material’s surface. Here, we demonstrate that surface acoustic waves (SAWs can enhance the chemical functionalization of gold films. This is shown by using an integrated biochip composed by a microfluidic channel coupled to a surface plasmon resonance (SPR readout system and by monitoring the adhesion of biotin-thiol on the gold SPR areas in different conditions. In the case of SAW-induced streaming, the functionalization efficiency is improved ≈ 5 times with respect to the case without SAWs. The technology here proposed can be easily applied to a wide variety of biological systems (e.g., proteins, nucleic acids and devices (e.g., sensors, devices for cell cultures.

  14. Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications

    Science.gov (United States)

    Wu, Wei; Wu, Zhaohui; Yu, Taekyung; Jiang, Changzhong; Kim, Woo-Sik

    2015-01-01

    This review focuses on the recent development and various strategies in the preparation, microstructure, and magnetic properties of bare and surface functionalized iron oxide nanoparticles (IONPs); their corresponding biological application was also discussed. In order to implement the practical in vivo or in vitro applications, the IONPs must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of IONPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The new functionalized strategies, problems and major challenges, along with the current directions for the synthesis, surface functionalization and bioapplication of IONPs, are considered. Finally, some future trends and the prospects in these research areas are also discussed. PMID:27877761

  15. Orientations of Liquid Crystals in Contact with Surfaces that Present Continuous Gradients of Chemical Functionality

    International Nuclear Information System (INIS)

    Clare, B.; Efimenko, K.; Fischer, D.; Genzer, J.; Abbott, N.

    2006-01-01

    We report the formation of continuous spatial gradients in the density of grafted semifluorinated chains on silicon oxide surfaces by vapor-phase diffusion of semifluorinated silanes. We quantify the orientations of the nematic liquid crystal (LC) 4-cyano-4'-pentylbiphenyl on these surfaces as a function of local surface composition obtained by using NEXAFS. These measurements demonstrate that it is possible to obtain the full range of tilt angles of a LC on these surfaces. We also use the data provided by these gradient surfaces to test hypotheses regarding the nature of the interaction between the LC and surfaces that give rise to the range of tilted orientations of the LC. We conclude that the orientations of the LC are not determined solely by the density of grafted semifluorinated chains or by the density of residual hydroxyl groups presented at these surfaces following reactions with the silanes. Instead, our results raise the possibility that the tilt angles of the semifluorinated chains on these surfaces (which are a function of the density of the grafted chains) may influence the orientation of the LC. These results, when combined, demonstrate the potential utility of gradient surfaces for screening surface chemistries that achieve desired orientations of LCs as well as for rapidly assembling experimental data sets that can be used to test propositions regarding mechanisms of anchoring LCs at surfaces

  16. Density-functional calculations of the surface tension of liquid Al and Na

    Science.gov (United States)

    Stroud, D.; Grimson, M. J.

    1984-01-01

    Calculations of the surface tensions of liquid Al and Na are described using the full ionic density functional formalism of Wood and Stroud (1983). Surface tensions are in good agreement with experiment in both cases, with results substantially better for Al than those found previously in the gradient approximation. Preliminary minimization with respect to surface profile leads to an oscillatory profile superimposed on a nearly steplike ionic density disribution; the oscillations have a wavellength of about a hardsphere diameter.

  17. Effect of surface loading on the hydro-mechanical response of a tunnel in saturated ground

    Directory of Open Access Journals (Sweden)

    Simon Heru Prassetyo

    2016-09-01

    Full Text Available The design of underground spaces in urban areas must account not only for the current overburden load but also for future surface loads, such as from construction of high-rise buildings above underground structures. In saturated ground, the surface load will generate an additional mechanical response through stress changes and ground displacement, as well as a hydraulic response through pore pressure changes. These hydro-mechanical (H-M changes can severely influence tunnel stability. This paper examines the effect of surface loading on the H-M response of a typical horseshoe-shaped tunnel in saturated ground. Two tunnel models were created in the computer code Fast Lagrangian Analysis of Continua (FLAC. One model represented weak and low permeability ground (stiff clay, and the other represented strong and high permeability ground (weathered granite. Each of the models was run under two liner permeabilities: permeable and impermeable. Two main cases were compared. In Case 1, the surface load was applied 10 years after tunnel construction. In Case 2, the surface load was applied after the steady state pore pressure condition was achieved. The simulation results show that tunnels with impermeable liners experienced the most severe influence from the surface loading, with high pore pressures, large inward displacement around the tunnels, and high bending moments in the liner. In addition, the severity of the response increased toward steady state. This induced H-M response was worse for tunnels in clay than for those in granite. Furthermore, the long-term liner stabilities in Case 1 and Case 2 were similar, indicating that the influence of the length of time between when the tunnel was completed and when the surface load was applied was negligible. These findings suggest that under surface loading, in addition to the ground strength, tunnel stability in saturated ground is largely influenced by liner permeability and the long-term H-M response of

  18. The transient response for different types of erodable surface thermocouples using finite element analysis

    Directory of Open Access Journals (Sweden)

    Mohammed Hussein

    2007-01-01

    Full Text Available The transient response of erodable surface thermocouples has been numerically assessed by using a two dimensional finite element analysis. Four types of base metal erodable surface thermocouples have been examined in this study, included type-K (alumel-chromel, type-E (chromel-constantan, type-T (copper-constantan, and type-J (iron-constantan with 50 mm thick- ness for each. The practical importance of these types of thermocouples is to be used in internal combustion engine studies and aerodynamics experiments. The step heat flux was applied at the surface of the thermocouple model. The heat flux from the measurements of the surface temperature can be commonly identified by assuming that the heat transfer within these devices is one-dimensional. The surface temperature histories at different positions along the thermocouple are presented. The normalized surface temperature histories at the center of the thermocouple for different types at different response time are also depicted. The thermocouple response to different heat flux variations were considered by using a square heat flux with 2 ms width, a sinusoidal surface heat flux variation width 10 ms period and repeated heat flux variation with 2 ms width. The present results demonstrate that the two dimensional transient heat conduction effects have a significant influence on the surface temperature history measurements made with these devices. It was observed that the surface temperature history and the transient response for thermocouple type-E are higher than that for other types due to the thermal properties of this thermocouple. It was concluded that the thermal properties of the surrounding material do have an impact, but the properties of the thermocouple and the insulation materials also make an important contribution to the net response.

  19. A comparison of reflectance properties on polymer micro-structured functional surface

    DEFF Research Database (Denmark)

    Regi, Francesco; Li, Dongya; Nielsen, Jannik Boll

    In this study, a functional micro-structure surface [1] has been developed as a combination of arrays of micro ridges. The scope of the surface is to achieve specific directional optical properties: that is, under constrained lighting, maximizing the reflectance from a certain viewing direction, ...

  20. Ab initio and work function and surface energy anisotropy of LaB6

    NARCIS (Netherlands)

    Uijttewaal, M. A.; de Wijs, G. A.; de Groot, R. A.

    2006-01-01

    Lanthanum hexaboride is one of the cathode materials most used in high-power electronics technology, but the many experimental results do not provide a consistent picture of the surface properties. Therefore, we report the first ab initio calculations of the work functions and surface energies of

  1. Grafting of functionalized polymer on porous silicon surface using Grignard reagent

    Science.gov (United States)

    Tighilt, F.-Z.; Belhousse, S.; Sam, S.; Hamdani, K.; Lasmi, K.; Chazalviel, J. N.; Gabouze, N.

    2017-11-01

    Recently, considerable attention has been paid to the manipulation and the control of the physicochemical properties of porous silicon surfaces because of their crucial importance to the modern microelectronics industry. Hybrid structures consisting of deposited polymer on porous silicon surfaces are important to applications in microelectronics, photovoltaics and sensors (Ensafi et al., 2016; Kashyout et al., 2015; Osorio et al.; 2015; Hejjo et al., 2002) [1-4]. In many cases, the polymer can provide excellent mechanical and chemical protection of the substrate, changes the electrochemical interface characteristics of the substrate, and provides new ways to the functionalization of porous silicon surfaces for molecular recognition and sensing. In this work, porous silicon surface was modified by anodic treatment in ethynylmagnesium bromide electrolyte leading to the formation of a polymeric layer bearing some bromine substituents. Subsequently, the formed polymer is functionalized with amine molecules containing functional groups (carboxylic acid or pyridine) by a substitution reaction between bromine sites and amine groups (Hofmann reaction). The chemical composition of the modified porous silicon surfaces was investigated and the grafting of polymeric chains and functional groups on the porous silicon surface was confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) which displayed the principal characteristic peaks attributed to the different functional groups. Furthermore, the surface of the material was examined by scanning electron microscopy (SEM).

  2. Versatile Surface Functionalization of Metal-Organic Frameworks through Direct Metal Coordination with a Phenolic Lipid Enables Diverse Applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wei [Univ. of New Mexico, Albuquerque, NM (United States); Xiang, Guolei [Univ. of Cambridge (United Kingdom); Shang, Jin [Univ. of Hong Kong (China); Guo, Jimin [Univ. of New Mexico, Albuquerque, NM (United States); Motevalli, Benyamin [Monash Univ., Clayton, VIC (Australia); Durfee, Paul [Univ. of New Mexico, Albuquerque, NM (United States); Agola, Jacob Ongudi [Univ. of New Mexico, Albuquerque, NM (United States); Coker, Eric N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brinker, C. Jeffrey [Univ. of New Mexico, Albuquerque, NM (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2018-02-22

    Here, a novel strategy for the versatile functionalization of the external surface of metal-organic frameworks (MOFs) has been developed based on the direct coordination of a phenolic-inspired lipid molecule DPGG (1,2-dipalmitoyl-sn-glycero-3-galloyl) with metal nodes/sites surrounding MOF surface. X-ray diffraction and Argon sorption analysis prove that the modified MOF particles retain their structural integrity and porosity after surface modification. Density functional theory calculations reveal that strong chelation strength between the metal sites and the galloyl head group of DPGG is the basic prerequisite for successful coating. Due to the pH-responsive nature of metal-phenol complexation, the modification process is reversible by simple washing in weak acidic water, showing an excellent regeneration ability for water-stable MOFs. Moreover, the colloidal stability of the modified MOFs in the nonpolar solvent allows them to be further organized into 2 dimensional MOF or MOF/polymer monolayers by evaporation-induced interfacial assembly conducted on an air/water interface. Lastly, the easy fusion of a second functional layer onto DPGG-modified MOF cores, enabled a series of MOF-based functional nanoarchitectures, such as MOFs encapsulated within hybrid supported lipid bilayers (so-called protocells), polyhedral core-shell structures, hybrid lipid-modified-plasmonic vesicles and multicomponent supraparticles with target functionalities, to be generated. for a wide range of applications.

  3. Functionalization of CoCr surfaces with cell adhesive peptides to promote HUVECs adhesion and proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Castellanos, Maria Isabel, E-mail: maria.isabel.castellanos@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC), ETSEIB, 08028 Barcelona (Spain); Centre for Research in Nanoengineering (CRNE), UPC, 08028 Barcelona (Spain); Mas-Moruno, Carlos, E-mail: carles.mas.moruno@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC), ETSEIB, 08028 Barcelona (Spain); Centre for Research in Nanoengineering (CRNE), UPC, 08028 Barcelona (Spain); Grau, Anna, E-mail: agraugar@gmail.com [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC), ETSEIB, 08028 Barcelona (Spain); Centre for Research in Nanoengineering (CRNE), UPC, 08028 Barcelona (Spain); Serra-Picamal, Xavier, E-mail: xserrapicamal@gmail.com [Institute for Bioengineering of Catalonia (IBEC), 08028 Barcelona (Spain); University of Barcelona and CIBER-BBN, 08036 Barcelona (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona (Spain); Trepat, Xavier, E-mail: xtrepat@ub.edu [Institute for Bioengineering of Catalonia (IBEC), 08028 Barcelona (Spain); University of Barcelona and CIBER-BBN, 08036 Barcelona (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona (Spain); Albericio, Fernando, E-mail: fernando.albericio@irbbarcelona.org [Department of Chemistry, University of Barcelona, CIBER-BBN, 08028 Barcelona (Spain); Joner, Michael, E-mail: michaeljoner@me.com [Department of Cardiology, Deutsches Herzzentrum München, 80636 Munich (Germany); CVPath Institute, Gaithersburg, MD 20878 (United States); and others

    2017-01-30

    Highlights: • We immobilized peptides on CoCr alloy through physisorption and covalent bonding. • Surface activation is an essential step prior to silanization to enhance peptide attachment. • Biofunctionalized surface characteristics were discussed. • RGDS, YIGSR and combination peptides display an improved HUVECs adhesion and proliferation. - Abstract: Biomimetic surface modification with peptides that have specific cell-binding moieties is a promising approach to improve endothelialization of metal-based stents. In this study, we functionalized CoCr surfaces with RGDS, REDV, YIGSR peptides and their combinations to promote endothelial cells (ECs) adhesion and proliferation. An extensive characterization of the functionalized surfaces was performed by XPS analysis, surface charge and quartz crystal microbalance with dissipation monitoring (QCM-D), which demonstrated the successful immobilization of the peptides to the surface. Cell studies demonstrated that the covalent functionalization of CoCr surfaces with an equimolar combination of RGDS and YIGSR represents the most powerful strategy to enhance the early stages of ECs adhesion and proliferation, indicating a positive synergistic effect between the two peptide motifs. Although these peptide sequences slightly increased smooth muscle cells (SMCs) adhesion, these values were ten times lower than those observed for ECs. The combination of RGDS with the REDV sequence did not show synergistic effects in promoting the adhesion or proliferation of ECs. The strategy presented in this study holds great potential to overcome clinical limitations of current metal stents by enhancing their capacity to support surface endothelialization.

  4. Functional and structural mapping of human cerebral cortex: solutions are in the surfaces

    Science.gov (United States)

    Van Essen, D. C.; Drury, H. A.; Joshi, S.; Miller, M. I.

    1998-01-01

    The human cerebral cortex is notorious for the depth and irregularity of its convolutions and for its variability from one individual to the next. These complexities of cortical geography have been a chronic impediment to studies of functional specialization in the cortex. In this report, we discuss ways to compensate for the convolutions by using a combination of strategies whose common denominator involves explicit reconstructions of the cortical surface. Surface-based visualization involves reconstructing cortical surfaces and displaying them, along with associated experimental data, in various complementary formats (including three-dimensional native configurations, two-dimensional slices, extensively smoothed surfaces, ellipsoidal representations, and cortical flat maps). Generating these representations for the cortex of the Visible Man leads to a surface-based atlas that has important advantages over conventional stereotaxic atlases as a substrate for displaying and analyzing large amounts of experimental data. We illustrate this by showing the relationship between functionally specialized regions and topographically organized areas in human visual cortex. Surface-based warping allows data to be mapped from individual hemispheres to a surface-based atlas while respecting surface topology, improving registration of identifiable landmarks, and minimizing unwanted distortions. Surface-based warping also can aid in comparisons between species, which we illustrate by warping a macaque flat map to match the shape of a human flat map. Collectively, these approaches will allow more refined analyses of commonalities as well as individual differences in the functional organization of primate cerebral cortex.

  5. Theoretical studies of the work functions of Pd-based bimetallic surfaces

    International Nuclear Information System (INIS)

    Ding, Zhao-Bin; Wu, Feng; Wang, Yue-Chao; Jiang, Hong

    2015-01-01

    Work functions of Pd-based bimetallic surfaces, including mainly M/Pd(111), Pd/M, and Pd/M/Pd(111) (M = 4d transition metals, Cu, Au, and Pt), are studied using density functional theory. We find that the work function of these bimetallic surfaces is significantly different from that of parent metals. Careful analysis based on Bader charges and electron density difference indicates that the variation of the work function in bimetallic surfaces can be mainly attributed to two factors: (1) charge transfer between the two different metals as a result of their different intrinsic electronegativity, and (2) the charge redistribution induced by chemical bonding between the top two layers. The first factor can be related to the contact potential, i.e., the work function difference between two metals in direct contact, and the second factor can be well characterized by the change in the charge spilling out into vacuum. We also find that the variation in the work functions of Pd/M/Pd(111) surfaces correlates very well with the variation of the d-band center of the surface Pd atom. The findings in this work can be used to provide general guidelines to design new bimetallic surfaces with desired electronic properties

  6. Analysis of functional organic molecules at noble metal surfaces by means of vibrational spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Leyssner, Felix

    2011-10-24

    azobenzene incorporated into the SAM is analogous to the free molecule in solution with the determined cross sections being similar. Therefore we propose a direct (intramolecular) electronic excitation mechanism. Additionally we studied graphene nanoribbons (GNRs), which are thin flakes of graphene, characterized by their width and edge-structure. Electronic HREELS has been proven to be a powerful tool which enables us to directly measure the band gap of the GNRs on Au(111). Regarding sub-nanometer wide atomically precise GNRs we report the first measurement of the band gap. We gained insight into the dependence of the switching process regarding molecule/substrate-interactions and molecule/molecule-interactions. These interactions govern the adsorption geometry and electronic structure of the surface bound species as well as they are responsible for steric hindrance and intra-layer electronic coupling strength. We conclude that the physical mechanism governing the desired functionality may be influenced drastically by the electronic interaction with the substrate, so that purely geometrical arguments to predict the functionality of adsorbed molecules have to be taken with great caution. Our study demonstrates that both, the geometric and electronic structure of the complete molecule-substrate complex have to be taken into account for a successful reversible photoisomerization of surface bound molecular switches.

  7. Surface-functionalized nanoparticles for biosensing and imaging-guided therapeutics

    Science.gov (United States)

    Jiang, Shan; Win, Khin Yin; Liu, Shuhua; Teng, Choon Peng; Zheng, Yuangang; Han, Ming-Yong

    2013-03-01

    In this article, the very recent progress of various functional inorganic nanomaterials is reviewed including their unique properties, surface functionalization strategies, and applications in biosensing and imaging-guided therapeutics. The proper surface functionalization renders them with stability, biocompatibility and functionality in physiological environments, and further enables their targeted use in bioapplications after bioconjugation via selective and specific recognition. The surface-functionalized nanoprobes using the most actively studied nanoparticles (i.e., gold nanoparticles, quantum dots, upconversion nanoparticles, and magnetic nanoparticles) make them an excellent platform for a wide range of bioapplications. With more efforts in recent years, they have been widely developed as labeling probes to detect various biological species such as proteins, nucleic acids and ions, and extensively employed as imaging probes to guide therapeutics such as drug/gene delivery and photothermal/photodynamic therapy.

  8. Studying the glial cell response to biomaterials and surface topography for improving the neural electrode interface

    Science.gov (United States)

    Ereifej, Evon S.

    Neural electrode devices hold great promise to help people with the restoration of lost functions, however, research is lacking in the biomaterial design of a stable, long-term device. Current devices lack long term functionality, most have been found unable to record neural activity within weeks after implantation due to the development of glial scar tissue (Polikov et al., 2006; Zhong and Bellamkonda, 2008). The long-term effect of chronically implanted electrodes is the formation of a glial scar made up of reactive astrocytes and the matrix proteins they generate (Polikov et al., 2005; Seil and Webster, 2008). Scarring is initiated when a device is inserted into brain tissue and is associated with an inflammatory response. Activated astrocytes are hypertrophic, hyperplastic, have an upregulation of intermediate filaments GFAP and vimentin expression, and filament formation (Buffo et al., 2010; Gervasi et al., 2008). Current approaches towards inhibiting the initiation of glial scarring range from altering the geometry, roughness, size, shape and materials of the device (Grill et al., 2009; Kotov et al., 2009; Kotzar et al., 2002; Szarowski et al., 2003). Literature has shown that surface topography modifications can alter cell alignment, adhesion, proliferation, migration, and gene expression (Agnew et al., 1983; Cogan et al., 2005; Cogan et al., 2006; Merrill et al., 2005). Thus, the goals of the presented work are to study the cellular response to biomaterials used in neural electrode fabrication and assess surface topography effects on minimizing astrogliosis. Initially, to examine astrocyte response to various materials used in neural electrode fabrication, astrocytes were cultured on platinum, silicon, PMMA, and SU-8 surfaces, with polystyrene as the control surface. Cell proliferation, viability, morphology and gene expression was measured for seven days in vitro. Results determined the cellular characteristics, reactions and growth rates of astrocytes

  9. Functional Elements on SIRPα IgV domain Mediate Cell Surface Binding to CD47

    Science.gov (United States)

    Liu, Yuan; Tong, Qiao; Zhou, Yubin; Lee, Hsiau-Wei; Yang, Jenny J.; Bühring, Hans-Jörg; Chen, Yi-Tien; Ha, Binh; Chen, Celia X-J.; Zen, Ke

    2007-01-01

    Summary SIRPα and SIRPβ1, the two major isoforms of the signal regulatory protein (SIRP) family, are co-expressed in human leukocytes but mediate distinct extracellular binding interactions and divergent cell signaling responses. Previous studies have demonstrated that binding of SIRPα with CD47, another important cell surface molecule, through the extracellular IgV domain regulates important leukocyte functions including macrophage recognition, leukocyte adhesion and transmigration. Although SIRPβ1 shares highly homologous extracellular IgV structure with SIRPα, it does not bind to CD47. In this study, we defined key amino acid residues exclusively expressing in the IgV domain of SIRPα, but not SIRPβ1, which determine the extracellular binding interaction of SIRPα to CD47. These key residues include Gln67, a small hydrophobic amino acid (Ala or Val) at the 57th position and Met102. We found that Gln67 and Ala/Val57 are critical. Mutation of either of these residues abates SIRPα directly binding to CD47. Functional cell adhesion and leukocyte transmigration assays further demonstrated central roles of Gln67 and Ala/Val57 in SIRPα extracellular binding mediated cell interactions and cell migration. Another SIRPα-specific residue, Met102, appears to assist SIRPα IgV binding through Gln67 and Ala/Val57. An essential role of these amino acids in SIRPα binding to CD47 was further confirmed by introducing these residues into the SIRPβ1 IgV domain, which dramatically converts SIRPβ1 into a CD47-binding molecule. Our results thus revealed the molecular basis by which SIRPα selectively binds to CD47 and shed new light into the structural mechanisms of SIRP isoform mediated distinctive extracellular interactions and cellular responses. PMID:17070842

  10. Functional elements on SIRPalpha IgV domain mediate cell surface binding to CD47.

    Science.gov (United States)

    Liu, Yuan; Tong, Qiao; Zhou, Yubin; Lee, Hsiau-Wei; Yang, Jenny J; Bühring, Hans-Jörg; Chen, Yi-Tien; Ha, Binh; Chen, Celia X-J; Yang, Yang; Zen, Ke

    2007-01-19

    SIRPalpha and SIRPbeta1, the two major isoforms of the signal regulatory protein (SIRP) family, are co-expressed in human leukocytes but mediate distinct extracellular binding interactions and divergent cell signaling responses. Previous studies have demonstrated that binding of SIRPalpha with CD47, another important cell surface molecule, through the extracellular IgV domain regulates important leukocyte functions including macrophage recognition, leukocyte adhesion and transmigration. Although SIRPbeta1 shares highly homologous extracellular IgV structure with SIRPalpha, it does not bind to CD47. Here, we defined key amino acid residues exclusively expressing in the IgV domain of SIRPalpha, but not SIRPbeta1, which determine the extracellular binding interaction of SIRPalpha to CD47. These key residues include Gln67, a small hydrophobic amino acid (Ala or Val) at the 57th position and Met102. We found that Gln67 and Ala/Val57 are critical. Mutation of either of these residues abates SIRPalpha directly binding to CD47. Functional cell adhesion and leukocyte transmigration assays further demonstrated central roles of Gln67 and Ala/Val57 in SIRPalpha extracellular binding mediated cell interactions and cell migration. Another SIRPalpha-specific residue, Met102, appears to assist SIRPalpha IgV binding through Gln67 and Ala/Val57. An essential role of these amino acid residues in SIRPalpha binding to CD47 was further confirmed by introducing these residues into the SIRPbeta1 IgV domain, which dramatically converts SIRPbeta1 into a CD47-binding molecule. Our results thus revealed the molecular basis by which SIRPalpha binds to CD47 and shed new light into the structural mechanisms of SIRP isoform mediated distinctive extracellular interactions and cellular responses.

  11. Hybrid response surface methodology-artificial neural network optimization of drying process of banana slices in a forced convective dryer.

    Science.gov (United States)

    Taheri-Garavand, Amin; Karimi, Fatemeh; Karimi, Mahmoud; Lotfi, Valiullah; Khoobbakht, Golmohammad

    2018-06-01

    The aim of the study is to fit models for predicting surfaces using the response surface methodology and the artificial neural network to optimize for obtaining the maximum acceptability using desirability functions methodology in a hot air drying process of banana slices. The drying air temperature, air velocity, and drying time were chosen as independent factors and moisture content, drying rate, energy efficiency, and exergy efficiency were dependent variables or responses in the mentioned drying process. A rotatable central composite design as an adequate method was used to develop models for the responses in the response surface methodology. Moreover, isoresponse contour plots were useful to predict the results by performing only a limited set of experiments. The optimum operating conditions obtained from the artificial neural network models were moisture content 0.14 g/g, drying rate 1.03 g water/g h, energy efficiency 0.61, and exergy efficiency 0.91, when the air temperature, air velocity, and drying time values were equal to -0.42 (74.2 ℃), 1.00 (1.50 m/s), and -0.17 (2.50 h) in the coded units, respectively.

  12. Post-treatment of molasses wastewater by electrocoagulation and process optimization through response surface analysis.

    Science.gov (United States)

    Tsioptsias, C; Petridis, D; Athanasakis, N; Lemonidis, I; Deligiannis, A; Samaras, P

    2015-12-01

    Molasses wastewater is a high strength effluent of food industry such as distilleries, sugar and yeast production plants etc. It is characterized by a dark brown color and exhibits a high content in substances of recalcitrant nature such as melanoidins. In this study, electrocoagulation (EC) was studied as a post treatment step for biologically treated molasses wastewater with high nitrogen content obtained from a baker's yeast industry. Iron and copper electrodes were used in various forms; the influence and interaction of current density, molasses wastewater dilution, and reaction time, on COD, color, ammonium and nitrate removal rates and operating cost were studied and optimized through Box Behnken's response surface analysis. Reaction time varied from 0.5 to 4 h, current density varied from 5 to 40 mA/cm(2) and dilution from 0 to 90% (v/v expressed as water concentration). pH, conductivity and temperature measurements were also carried out during each experiment. From preliminary experiments, it was concluded that the application of aeration and sample dilution, considerably influenced the kinetics of the process. The obtained results showed that COD removal varied between 10 and 54%, corresponding to an operation cost ranging from 0.2 to 33 euro/kg COD removed. Significant removal rates were obtained for nitrogen as nitrate and ammonium (i.e. 70% ammonium removal). A linear relation of COD and ammonium to the design parameters was observed, while operation cost and nitrate removal responded in a curvilinear function. A low ratio of electrode surface to treated volume was used, associated to a low investment cost; in addition, iron wastes could be utilized as low cost electrodes i.e. iron fillings from lathes, aiming to a low operation cost due to electrodes replacement. In general, electrocoagulation proved to be an effective and low cost process for biologically treated molasses-wastewater treatment for additional removal of COD and nitrogen content and

  13. Microarray of neuroblastoma cells on the selectively functionalized nanocrystalline diamond thin film surface

    Energy Technology Data Exchange (ETDEWEB)

    Park, Young-Sang; Son, Hyeong-Guk; Kim, Dae-Hoon; Oh, Hong-Gi; Lee, Da-Som; Kim, Min-Hye; Lim, Ki-Moo; Song, Kwang-Soup, E-mail: kssong10@kumoh.ac.kr

    2016-01-15

    Graphical abstract: - Highlights: • The nanocrystalline diamond (NCD) surface is functionalized with F or O. • The cell adhesion and growth are evaluated on the functionalized NCD surface. • The cell adhesion and growth depend on the wettability of the surface. • Cell patterning was achieved by using of hydrophilic and hydrophobic surfaces. • Neuroblastoma cells were arrayed on the micro-patterned NCD surface. - Abstract: Nanocrystalline diamond (NCD) film surfaces were modified with fluorine or oxygen by plasma treatment in an O{sub 2} or C{sub 3}F{sub 8} gas environment in order to induce wettability. The oxygenated-NCD (O-NCD) film surface was hydrophilic and the fluorinated-NCD (F-NCD) surface was hydrophobic. The efficiency of early cell adhesion, which is dependent on the wettability of the cell culture plate and necessary for the growth and proliferation of cells, was 89.62 ± 3.92% on the O-NCD film and 7.78 ± 0.77% on the F-NCD film surface after 3 h of cell culture. The wettability of the NCD film surface was artificially modified using a metal mask and plasma treatment to fabricate a micro-pattern. Four types of micro-patterns were fabricated (line, circle, mesh, and word) on the NCD film surface. We precisely arrayed the neuroblastoma cells on the micro-patterned NCD film surfaces by controlling the surface wettability and cell seeding density. The neuroblastoma cells adhered and proliferated along the O-NCD film surface.

  14. Simulations of Coulomb systems confined by polarizable surfaces using periodic Green functions.

    Science.gov (United States)

    Dos Santos, Alexandre P; Girotto, Matheus; Levin, Yan

    2017-11-14

    We present an efficient approach for simulating Coulomb systems confined by planar polarizable surfaces. The method is based on the solution of the Poisson equation using periodic Green functions. It is shown that the electrostatic energy arising from the surface polarization can be decoupled from the energy due to the direct Coulomb interaction between the ions. This allows us to combine an efficient Ewald summation method, or any other fast method for summing over the replicas, with the polarization contribution calculated using Green function techniques. We apply the method to calculate density profiles of ions confined between the charged dielectric and metal surfaces.

  15. Fluorination of vertically aligned carbon nanotubes: from CF4 plasma chemistry to surface functionalization.

    Science.gov (United States)

    Struzzi, Claudia; Scardamaglia, Mattia; Colomer, Jean-François; Verdini, Alberto; Floreano, Luca; Snyders, Rony; Bittencourt, Carla

    2017-01-01

    The surface chemistry of plasma fluorinated vertically aligned carbon nanotubes (vCNT) is correlated to the CF 4 plasma chemical composition. The results obtained via FTIR and mass spectrometry are combined with the XPS and Raman analysis of the sample surface showing the dependence on different plasma parameters (power, time and distance from the plasma region) on the resulting fluorination. Photoemission and absorption spectroscopies are used to investigate the evolution of the electronic properties as a function of the fluorine content at the vCNT surface. The samples suffer a limited ageing effect, with a small loss of fluorine functionalities after two weeks in ambient conditions.

  16. Fluorination of vertically aligned carbon nanotubes: from CF4 plasma chemistry to surface functionalization

    Directory of Open Access Journals (Sweden)

    Claudia Struzzi

    2017-08-01

    Full Text Available The surface chemistry of plasma fluorinated vertically aligned carbon nanotubes (vCNT is correlated to the CF4 plasma chemical composition. The results obtained via FTIR and mass spectrometry are combined with the XPS and Raman analysis of the sample surface showing the dependence on different plasma parameters (power, time and distance from the plasma region on the resulting fluorination. Photoemission and absorption spectroscopies are used to investigate the evolution of the electronic properties as a function of the fluorine content at the vCNT surface. The samples suffer a limited ageing effect, with a small loss of fluorine functionalities after two weeks in ambient conditions.

  17. Self-consistent Green’s-function technique for surfaces and interfaces

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Rosengaard, N. M.

    1991-01-01

    We have implemented an efficient self-consistent Green’s-function technique for calculating ground-state properties of surfaces and interfaces, based on the linear-muffin-tin-orbitals method within the tight-binding representation. In this approach the interlayer interaction is extremely short...... ranged, and only a few layers close to the interface need be treated self-consistently via a Dyson equation. For semi-infinite jellium, the technique gives work functions and surface energies that are in excellent agreement with earlier calculations. For the bcc(110) surface of the alkali metals, we find...

  18. Surface structures and dielectric response of ultrafine BaTiO3 particles

    International Nuclear Information System (INIS)

    Jiang, B.; Peng, J.L.; Bursill, L.A.

    1998-01-01

    Characteristic differences are observed for the dielectric response and microstructures of BaTiO 3 nanoscale fine powders prepared using sol gel (SG) and steric acid gel (SAG) methods. The former exhibit a critical size below which there is no paraelectric/ferroelectric phase transition whereas BaTiO 3 prepared via the SAG route remained cubic for all conditions. Atomic resolution images of both varieties showed a high density of interesting surface steps and facets. Computer simulated images of surface structure models showed that the outer (100) surface was typically a BaO layer and that at corners and ledges the steps are typically finished with Ba+2 ions; i.e. the surfaces and steps are Ba-rich. Otherwise the surfaces were typically clean and free of amorphous layers. The relationship between the observed surfaces structures and theoretical models for size effects on the dielectric properties is discussed. (authors)

  19. UV laser-ablated surface textures as potential regulator of cellular response.

    Science.gov (United States)

    Chandra, Prafulla; Lai, Karen; Sung, Hak-Joon; Murthy, N Sanjeeva; Kohn, Joachim

    2010-06-01

    Textured surfaces obtained by UV laser ablation of poly(ethylene terephthalate) films were used to study the effect of shape and spacing of surface features on cellular response. Two distinct patterns, cones and ripples with spacing from 2 to 25 μm, were produced. Surface features with different shapes and spacings were produced by varying pulse repetition rate, laser fluence, and exposure time. The effects of the surface texture parameters, i.e., shape and spacing, on cell attachment, proliferation, and morphology of neonatal human dermal fibroblasts and mouse fibroblasts were studied. Cell attachment was the highest in the regions with cones at ∼4 μm spacing. As feature spacing increased, cell spreading decreased, and the fibroblasts became more circular, indicating a stress-mediated cell shrinkage. This study shows that UV laser ablation is a useful alternative to lithographic techniques to produce surface patterns for controlling cell attachment and growth on biomaterial surfaces.

  20. Functional trait responses to sediment deposition reduce macrofauna-mediated ecosystem functioning in an estuarine mudflat

    Science.gov (United States)

    Mestdagh, Sebastiaan; Bagaço, Leila; Braeckman, Ulrike; Ysebaert, Tom; De Smet, Bart; Moens, Tom; Van Colen, Carl

    2018-05-01

    Human activities, among which dredging and land use change in river basins, are altering estuarine ecosystems. These activities may result in changes in sedimentary processes, affecting biodiversity of sediment macrofauna. As macrofauna controls sediment chemistry and fluxes of energy and matter between water column and sediment, changes in the structure of macrobenthic communities could affect the functioning of an entire ecosystem. We assessed the impact of sediment deposition on intertidal macrobenthic communities and on rates of an important ecosystem function, i.e. sediment community oxygen consumption (SCOC). An experiment was performed with undisturbed sediment samples from the Scheldt river estuary (SW Netherlands). The samples were subjected to four sedimentation regimes: one control and three with a deposited sediment layer of 1, 2 or 5 cm. Oxygen consumption was measured during incubation at ambient temperature. Luminophores applied at the surface, and a seawater-bromide mixture, served as tracers for bioturbation and bio-irrigation, respectively. After incubation, the macrofauna was extracted, identified, and counted and then classified into functional groups based on motility and sediment reworking capacity. Total macrofaunal densities dropped already under the thinnest deposits. The most affected fauna were surficial and low-motility animals, occurring at high densities in the control. Their mortality resulted in a drop in SCOC, which decreased steadily with increasing deposit thickness, while bio-irrigation and bioturbation activity showed increases in the lower sediment deposition regimes but decreases in the more extreme treatments. The initial increased activity likely counteracted the effects of the drop in low-motility, surficial fauna densities, resulting in a steady rather than sudden fall in oxygen consumption. We conclude that the functional identity in terms of motility and sediment reworking can be crucial in our understanding of the

  1. Functional trait responses to sediment deposition reduce macrofauna-mediated ecosystem functioning in an estuarine mudflat

    Directory of Open Access Journals (Sweden)

    S. Mestdagh

    2018-05-01

    Full Text Available Human activities, among which dredging and land use change in river basins, are altering estuarine ecosystems. These activities may result in changes in sedimentary processes, affecting biodiversity of sediment macrofauna. As macrofauna controls sediment chemistry and fluxes of energy and matter between water column and sediment, changes in the structure of macrobenthic communities could affect the functioning of an entire ecosystem. We assessed the impact of sediment deposition on intertidal macrobenthic communities and on rates of an important ecosystem function, i.e. sediment community oxygen consumption (SCOC. An experiment was performed with undisturbed sediment samples from the Scheldt river estuary (SW Netherlands. The samples were subjected to four sedimentation regimes: one control and three with a deposited sediment layer of 1, 2 or 5 cm. Oxygen consumption was measured during incubation at ambient temperature. Luminophores applied at the surface, and a seawater–bromide mixture, served as tracers for bioturbation and bio-irrigation, respectively. After incubation, the macrofauna was extracted, identified, and counted and then classified into functional groups based on motility and sediment reworking capacity. Total macrofaunal densities dropped already under the thinnest deposits. The most affected fauna were surficial and low-motility animals, occurring at high densities in the control. Their mortality resulted in a drop in SCOC, which decreased steadily with increasing deposit thickness, while bio-irrigation and bioturbation activity showed increases in the lower sediment deposition regimes but decreases in the more extreme treatments. The initial increased activity likely counteracted the effects of the drop in low-motility, surficial fauna densities, resulting in a steady rather than sudden fall in oxygen consumption. We conclude that the functional identity in terms of motility and sediment reworking can be crucial in our

  2. An optimal design of wind turbine and ship structure based on neuro-response surface method

    Directory of Open Access Journals (Sweden)

    Jae-Chul Lee

    2015-07-01

    Full Text Available The geometry of engineering systems affects their performances. For this reason, the shape of engineering systems needs to be optimized in the initial design stage. However, engineering system design problems consist of multi-objective optimization and the performance analysis using commercial code or numerical analysis is generally time-consuming. To solve these problems, many engineers perform the optimization using the approximation model (response surface. The Response Surface Method (RSM is generally used to predict the system performance in engi-neering research field, but RSM presents some prediction errors for highly nonlinear systems. The major objective of this research is to establish an optimal design method for multi-objective problems and confirm its applicability. The proposed process is composed of three parts: definition of geometry, generation of response surface, and optimization process. To reduce the time for performance analysis and minimize the prediction errors, the approximation model is generated using the Backpropagation Artificial Neural Network (BPANN which is considered as Neuro-Response Surface Method (NRSM. The optimization is done for the generated response surface by non-dominated sorting genetic algorithm-II (NSGA-II. Through case studies of marine system and ship structure (substructure of floating offshore wind turbine considering hydrodynamics performances and bulk carrier bottom stiffened panels considering structure performance, we have confirmed the applicability of the proposed method for multi-objective side constraint optimization problems.

  3. An optimal design of wind turbine and ship structure based on neuro-response surface method

    Science.gov (United States)

    Lee, Jae-Chul; Shin, Sung-Chul; Kim, Soo-Young

    2015-07-01

    The geometry of engineering systems affects their performances. For this reason, the shape of engineering systems needs to be optimized in the initial design stage. However, engineering system design problems consist of multi-objective optimization and the performance analysis using commercial code or numerical analysis is generally time-consuming. To solve these problems, many engineers perform the optimization using the approximation model (response surface). The Response Surface Method (RSM) is generally used to predict the system performance in engineering research field, but RSM presents some prediction errors for highly nonlinear systems. The major objective of this research is to establish an optimal design method for multi-objective problems and confirm its applicability. The proposed process is composed of three parts: definition of geometry, generation of response surface, and optimization process. To reduce the time for performance analysis and minimize the prediction errors, the approximation model is generated using the Backpropagation Artificial Neural Network (BPANN) which is considered as Neuro-Response Surface Method (NRSM). The optimization is done for the generated response surface by non-dominated sorting genetic algorithm-II (NSGA-II). Through case studies of marine system and ship structure (substructure of floating offshore wind turbine considering hydrodynamics performances and bulk carrier bottom stiffened panels considering structure performance), we have confirmed the applicability of the proposed method for multi-objective side constraint optimization problems.

  4. Multimodel Surface Temperature Responses to Removal of U.S. Sulfur Dioxide Emissions

    Science.gov (United States)

    Conley, A. J.; Westervelt, D. M.; Lamarque, J.-F.; Fiore, A. M.; Shindell, D.; Correa, G.; Faluvegi, G.; Horowitz, L. W.

    2018-03-01

    Three Earth System models are used to derive surface temperature responses to removal of U.S. anthropogenic SO2 emissions. Using multicentury perturbation runs with and without U.S. anthropogenic SO2 emissions, the local and remote surface temperature changes are estimated. In spite of a temperature drift in the control and large internal variability, 200 year simulations yield statistically significant regional surface temperature responses to the removal of U.S. SO2 emissions. Both local and remote surface temperature changes occur in all models, and the patterns of changes are similar between models for northern hemisphere land regions. We find a global average temperature sensitivity to U.S. SO2 emissions of 0.0055 K per Tg(SO2) per year with a range of (0.0036, 0.0078). We examine global and regional responses in SO4 burdens, aerosol optical depths (AODs), and effective radiative forcing (ERF). While changes in AOD and ERF are concentrated near the source region (United States), the temperature response is spread over the northern hemisphere with amplification of the temperature increase toward the Arctic. In all models, we find a significant response of dust concentrations, which affects the AOD but has no obvious effect on surface temperature. Temperature sensitivity to the ERF of U.S. SO2 emissions is found to differ from the models' sensitivity to radiative forcing of doubled CO2.

  5. Response function of semiconductor detectors, Ge and Si(Li)

    International Nuclear Information System (INIS)

    Zevallos Chavez, Juan Yury

    2003-01-01

    The Response Function (RF) for Ge and Si(Li) semiconductor detectors was obtained. The RF was calculated for five detectors, four Hp Ge with active volumes of 89 cm 3 , 50 cm 3 , 8 cm 3 and 5 cm 3 , and one Si(Li) with 0.143 cm 3 of active volume. The interval of energy studied ranged from 6 keV up to 1.5 MeV. Two kinds of studies were done in this work. The first one was the RF dependence with the detection geometry. Here the calculation of the RF for a geometry named as simple and an extrapolation of that RF, were both done. The extrapolation process analyzed both, spectra obtained with a shielding geometry and spectra where the source-detector distance was modified. The second one was the RF dependence with the detection electronics. This study was done varying the shaping time of the pulse in the detection electronics. The purpose was to verify the effect of the ballistic deficit in the resolution of the detector. This effect was not observed. The RF components that describe the region of the total absorption of the energy of the incident photons, and the partial absorption of this energy, were both treated. In particular, empirical functions were proposed for the treatment of both, the multiple scattering originated in the detector (crystal), and the photon scattering originated in materials of the neighborhood of the crystal. Another study involving Monte Carlo simulations was also done in order to comprehend the photon scattering structures produced in an iron shield. A deconvolution method is suggested, for spectra related to scattered radiation in order to assess the dose delivered to the scatterer. (author)

  6. Water Contact Angle Dependence with Hydroxyl Functional Groups on Silica Surfaces under CO2 Sequestration Conditions.

    Science.gov (United States)

    Chen, Cong; Zhang, Ning; Li, Weizhong; Song, Yongchen

    2015-12-15

    Functional groups on silica surfaces under CO2 sequestration conditions are complex due to reactions among supercritical CO2, brine and silica. Molecular dynamics simulations have been performed to investigate the effects of hydroxyl functional groups on wettability. It has been found that wettability shows a strong dependence on functional groups on silica surfaces: silanol number density, space distribution, and deprotonation/protonation degree. For neutral silica surfaces with crystalline structure (Q(3), Q(3)/Q(4), Q(4)), as silanol number density decreases, contact angle increases from 33.5° to 146.7° at 10.5 MPa and 318 K. When Q(3) surface changes to an amorphous structure, water contact angle increases 20°. Water contact angle decreases about 12° when 9% of silanol groups on Q(3) surface are deprotonated. When the deprotonation degree increases to 50%, water contact angle decreases to 0. The dependence of wettability on silica surface functional groups was used to analyze contact angle measurement ambiguity in literature. The composition of silica surfaces is complicated under CO2 sequestration conditions, the results found in this study may help to better understand wettability of CO2/brine/silica system.

  7. Concatenation of electrochemical grafting with chemical or electrochemical modification for preparing electrodes with specific surface functionality

    International Nuclear Information System (INIS)

    Verma, Pallavi; Maire, Pascal; Novak, Petr

    2011-01-01

    Surface modified electrodes are used in electro-analysis, electro-catalysis, sensors, biomedical applications, etc. and could also be used in batteries. The properties of modified electrodes are determined by the surface functionality. Therefore, the steps involved in the surface modification of the electrodes to obtain specific functionality are of prime importance. We illustrate here bridging of two routes of surface modifications namely electrochemical grafting, and chemical or electrochemical reduction. First, by electrochemical grafting an organic moiety is covalently immobilized on the surface. Then, either by chemical or by electrochemical route the terminal functional group of the grafted moiety is transformed. Using the former route we prepared lithium alkyl carbonate (-O(CH 2 ) 3 OCO 2 Li) modified carbon with potential applications in batteries, and employing the latter we prepared phenyl hydroxyl amine (-C 6 H 4 NHOH) modified carbon which may find application in biosensors. Benzyl alcohol (-C 6 H 4 CH 2 OH) modified carbon was prepared by both chemical as well as electrochemical route. We report combinations of conjugating the two steps of surface modifications and show how the optimal route of terminal functional group modification depends on the chemical nature of the moiety attached to the surface in the electrochemical grafting step.

  8. Concatenation of electrochemical grafting with chemical or electrochemical modification for preparing electrodes with specific surface functionality

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Pallavi; Maire, Pascal [Paul Scherrer Institut, Electrochemistry Laboratory, Section Electrochemical Energy Storage, CH-5232 Villigen PSI (Switzerland); Novak, Petr, E-mail: petr.novak@psi.c [Paul Scherrer Institut, Electrochemistry Laboratory, Section Electrochemical Energy Storage, CH-5232 Villigen PSI (Switzerland)

    2011-04-01

    Surface modified electrodes are used in electro-analysis, electro-catalysis, sensors, biomedical applications, etc. and could also be used in batteries. The properties of modified electrodes are determined by the surface functionality. Therefore, the steps involved in the surface modification of the electrodes to obtain specific functionality are of prime importance. We illustrate here bridging of two routes of surface modifications namely electrochemical grafting, and chemical or electrochemical reduction. First, by electrochemical grafting an organic moiety is covalently immobilized on the surface. Then, either by chemical or by electrochemical route the terminal functional group of the grafted moiety is transformed. Using the former route we prepared lithium alkyl carbonate (-O(CH{sub 2}){sub 3}OCO{sub 2}Li) modified carbon with potential applications in batteries, and employing the latter we prepared phenyl hydroxyl amine (-C{sub 6}H{sub 4}NHOH) modified carbon which may find application in biosensors. Benzyl alcohol (-C{sub 6}H{sub 4}CH{sub 2}OH) modified carbon was prepared by both chemical as well as electrochemical route. We report combinations of conjugating the two steps of surface modifications and show how the optimal route of terminal function