Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Surface

  • PDM surface
  • ab initio potential energy surface
  • abaxial surface
  • abiotic surface
  • acrylic surface
  • adaxial leaf surface
  • adaxial surface
  • adhesive surface
  • adsorbent surface
  • ag surface
  • agar surface
  • alloy surface
  • alumina surface
  • anterior surface
  • apical surface
  • articular surface
  • artificial surface
  • au surface
  • auricular surface
  • bacterial surface
  • bare surface
  • basal surface
  • basolateral surface
  • bead surface
  • binding surface
  • biofilm surface
  • biomimetic surface
  • biosensor surface
  • black surface
  • body surface
  • bone surface
  • bottom surface
  • boundary surface
  • bounding surface
  • brain surface
  • buccal surface
  • carbon black surface
  • carbon electrode surface
  • carbon surface
  • carious surface
  • cartilage surface
  • catalyst surface
  • cell surface
  • ceramic surface
  • channel surface
  • charged surface
  • chip surface
  • chiral surface
  • clay surface
  • climate surface
  • cnt surface
  • collector surface
  • colloidal silver surface
  • complex surface
  • composite surface
  • concrete surface
  • conducting surface
  • conjunctival surface
  • contact surface
  • contacting surface
  • contaminated surface
  • control surface
  • convex surface
  • copper surface
  • corneal surface
  • cortical surface
  • crystal surface
  • cu surface
  • curved surface
  • cut surface
  • cylinder surface
  • cylindrical surface
  • cytoplasmic surface
  • de la surface
  • de surface
  • deformable surface
  • dental surface
  • dentin surface
  • dentine surface
  • diamond surface
  • different surface
  • discontinuity surface
  • distal surface
  • dorsal surface
  • dry surface
  • earth land surface
  • earth surface
  • electrode surface
  • electrostatic potential surface
  • enamel surface
  • endocardial surface
  • endosteal surface
  • endothelial surface
  • energy surface
  • entire surface
  • epicardial surface
  • epithelial cell surface
  • epithelial surface
  • erosion surface
  • erosional surface
  • etched surface
  • exposed root surface
  • exposed surface
  • extensor surface
  • exterior surface
  • external surface
  • extracellular surface
  • eye surface
  • failure surface
  • fermi surface
  • fiber surface
  • fibre surface
  • film surface
  • fitness surface
  • flat surface
  • flooding surface
  • fluid surface
  • food surface
  • fracture surface
  • fractured surface
  • free surface
  • frequency-selective surface
  • front surface
  • functional surface
  • functionalized surface
  • glacier surface
  • glass fiber surface
  • glass surface
  • glassy carbon electrode surface
  • gold surface
  • graphite surface
  • grinding surface
  • ground surface
  • growth surface
  • ha surface
  • hair surface
  • hard surface
  • heat transfer surface
  • heating surface
  • heterogeneous surface
  • horizontal surface
  • hybrid surface
  • hydrogel surface
  • hydrophilic surface
  • hydrophobic surface
  • ice surface
  • implant surface
  • implicit surface
  • inclined surface
  • initio potential energy surface
  • inn surface
  • inner surface
  • inorganic surface
  • interaction surface
  • internal surface
  • intestinal surface
  • iron surface
  • irregular surface
  • ito surface
  • joint surface
  • la surface
  • labial surface
  • lake surface
  • land surface
  • lateral surface
  • leaf surface
  • lens surface
  • lingual dorsal surface
  • lingual surface
  • liquid surface
  • liver surface
  • lower surface
  • luminal surface
  • machined surface
  • magnetic surface
  • material surface
  • medial surface
  • membrane surface
  • mesial surface
  • metal oxide surface
  • metal surface
  • metallic surface
  • mgo surface
  • mica surface
  • mineral surface
  • mineralizing surface
  • minimal surface
  • model surface
  • modified surface
  • mold surface
  • molecular surface
  • moving surface
  • mucosal surface
  • nanoparticle surface
  • nanotube surface
  • natural surface
  • near surface
  • neuronal surface
  • new surface
  • occlusal surface
  • ocular surface
  • one surface
  • osteoclast surface
  • osteoid surface
  • other surface
  • outer surface
  • oxide surface
  • oxidized surface
  • palmar surface
  • paper surface
  • parasite surface
  • particle surface
  • patterned surface
  • pet surface
  • phreatic surface
  • pial surface
  • planar surface
  • plane surface
  • plant surface
  • plantar surface
  • plastic surface
  • plate surface
  • platelet surface
  • platinum surface
  • polar surface
  • polished surface
  • polyethylene surface
  • polymer surface
  • polymeric surface
  • polystyrene surface
  • pore surface
  • porous silicon surface
  • porous surface
  • posterior surface
  • potential energy surface
  • potential surface
  • potential-energy surface
  • powder surface
  • protein surface
  • proximal surface
  • quartz surface
  • reaching the earth surface
  • reaction surface
  • reactive surface
  • reflecting surface
  • resorption surface
  • response surface
  • retinal surface
  • rigid surface
  • road surface
  • rock surface
  • root surface
  • rough surface
  • rougher surface
  • rugged surface
  • same surface
  • sample surface
  • sand surface
  • sea surface
  • sediment surface
  • semiconductor surface
  • shell surface
  • side surface
  • silica surface
  • silicon surface
  • silver surface
  • skin surface
  • sla surface
  • slide surface
  • sliding surface
  • smooth surface
  • smoother surface
  • smoothest surface
  • soft surface
  • soil surface
  • solid surface
  • specific surface
  • specimen surface
  • sperm surface
  • spherical surface
  • stainless steel surface
  • steel surface
  • stellar surface
  • stone surface
  • substrate surface
  • superhydrophobic surface
  • support surface
  • switching surface
  • swnt surface
  • target surface
  • terrestrial surface
  • the earth surface
  • tio2 surface
  • tissue surface
  • titanium implant surface
  • titanium surface
  • tongue surface
  • tooth surface
  • top surface
  • transfer surface
  • treated surface
  • tumor surface
  • uncoated surface
  • underlying surface
  • uneven surface
  • upper surface
  • various surface
  • ventral surface
  • vertical surface
  • very smooth surface
  • wall surface
  • water surface
  • wing surface
  • wire surface
  • wood surface
  • wound surface
  • yield surface
  • zno surface

  • Terms modified by Surface

  • surface accessibility
  • surface accumulation
  • surface acoustic wave
  • surface activation
  • surface activity
  • surface adhesion
  • surface adsorption
  • surface air temperature
  • surface albedo
  • surface analysis
  • surface anatomy
  • surface antibody
  • surface antigen
  • surface appearance
  • surface area
  • surface area available
  • surface area measurement
  • surface area value
  • surface atom
  • surface barrier
  • surface binding
  • surface brightness
  • surface brightness profile
  • surface cell
  • surface change
  • surface characteristic
  • surface characterization
  • surface charge
  • surface charge density
  • surface charge distribution
  • surface chemistry
  • surface cleaning
  • surface co2 efflux
  • surface coat
  • surface coating
  • surface coil
  • surface color
  • surface colour
  • surface complex
  • surface component
  • surface composition
  • surface concentration
  • surface condition
  • surface configuration
  • surface contact
  • surface contamination
  • surface cooling
  • surface corresponding
  • surface coverage
  • surface crack
  • surface crystallization
  • surface current
  • surface current distribution
  • surface damage
  • surface data
  • surface decreased
  • surface defect
  • surface deformation
  • surface degradation
  • surface density
  • surface density profile
  • surface description
  • surface design
  • surface detail
  • surface diffusion
  • surface disease
  • surface displacement
  • surface display
  • surface display system
  • surface distribution
  • surface disturbance
  • surface ecg
  • surface ectoderm
  • surface eeg
  • surface effects
  • surface electrocardiogram
  • surface electrode
  • surface electromyographic
  • surface electromyography
  • surface electrostatic potential
  • surface element
  • surface elevation
  • surface emg
  • surface emg signal
  • surface emitting laser
  • surface energy
  • surface energy balance
  • surface engineering
  • surface enrichment
  • surface environment
  • surface epithelia
  • surface epithelial
  • surface epithelial cell
  • surface epithelium
  • surface erosion
  • surface exposure
  • surface expression
  • surface feature
  • surface field
  • surface film
  • surface finish
  • surface fire
  • surface flaw
  • surface flow
  • surface flux
  • surface formation
  • surface free energy
  • surface functional groups
  • surface functionality
  • surface functionalization
  • surface geometry
  • surface glycoprotein
  • surface grafting
  • surface gravity
  • surface groups
  • surface hardness
  • surface heat exchanger
  • surface heat flux
  • surface height
  • surface heterogeneity
  • surface horizon
  • surface hydration
  • surface hydrophilicity
  • surface hydrophobicity
  • surface hydroxyl groups
  • surface image
  • surface immobilization
  • surface impedance
  • surface implant
  • surface integral
  • surface integral equation
  • surface integrin
  • surface integrity
  • surface interaction
  • surface irregularity
  • surface kinetics
  • surface layer
  • surface lead
  • surface level
  • surface lipid
  • surface loading
  • surface localization
  • surface location
  • surface loop
  • surface loss
  • surface lowering
  • surface map
  • surface mapping
  • surface marker
  • surface marker expression
  • surface material
  • surface membrane
  • surface mesh
  • surface method
  • surface methodology
  • surface microstructure
  • surface model
  • surface modeling
  • surface models
  • surface modification
  • surface modifications
  • surface modifier
  • surface molecule
  • surface molecule expression
  • surface morphological
  • surface morphology
  • surface motility
  • surface motion
  • surface mutation
  • surface normal
  • surface observation
  • surface only
  • surface orientation
  • surface oxidation
  • surface oxide
  • surface parameter
  • surface passivation
  • surface patch
  • surface pattern
  • surface ph
  • surface phenotype
  • surface phonon
  • surface plasmon resonance
  • surface plasmon resonance analysis
  • surface plasmon resonance spectroscopy
  • surface plasticity
  • surface plot
  • surface point
  • surface polarity
  • surface polymerization
  • surface population
  • surface porosity
  • surface potential
  • surface preparation
  • surface pressure
  • surface process
  • surface profile
  • surface property
  • surface protection
  • surface protein
  • surface quality
  • surface radiation
  • surface reaction
  • surface reactivity
  • surface receptor
  • surface recognition
  • surface recombination
  • surface reconstruction
  • surface region
  • surface regions
  • surface relief grating
  • surface rendering
  • surface representation
  • surface residue
  • surface resistance
  • surface resistivity
  • surface resorption
  • surface roughness
  • surface runoff
  • surface rupture
  • surface salinity
  • surface sample
  • surface scanning
  • surface scattering
  • surface science
  • surface sediment
  • surface segregation
  • surface shape
  • surface shows
  • surface site
  • surface smoothing
  • surface smoothness
  • surface soil
  • surface soil sample
  • surface species
  • surface state
  • surface states
  • surface strain
  • surface stress
  • surface structure
  • surface temperature
  • surface temperature anomaly
  • surface temperature increase
  • surface temperature measurement
  • surface tension
  • surface tension force
  • surface tension measurement
  • surface termination
  • surface texture
  • surface textures
  • surface tissue
  • surface topography
  • surface traction
  • surface treatment
  • surface type
  • surface used
  • surface variable
  • surface velocity
  • surface warming
  • surface water
  • surface water body
  • surface water interaction
  • surface water resources
  • surface water sample
  • surface water temperature
  • surface wave
  • surface wear
  • surface weathering
  • surface wettability
  • surface wind

  • Selected Abstracts


    M. Dursapt
    First page of article [source]


    Louise Johnson MSc
    No abstract is available for this article. [source]


    ABSTRACT This study employed an insoluble solid particle, i.e. a potato starch used as an example, to investigate the impact of the concentration of such particles suspended in water (with solid loading of 5, 10, 20 and 30 wt%) upon the solid inclusion levels in ice layers formed on a sub-cooled smooth stainless steel plate surface. The effects of ice growth rate, bulk concentration and suspension velocity on insoluble solid inclusion, i.e. potato starch mass fraction, in ice layer were studied. The experiments, where potato starch is added into aqueous sucrose solutions or the reverse where sucrose is added into starch suspension, were also carried out to investigated effect of the starch particles on sucrose inclusion in ice and effect of solute (sucrose) on starch particle inclusion in ice. It has been found that solid inclusion in ice increases with increasing bulk concentration and average ice growth rate, at constant solution and coolant velocities, and increasing suspension velocity can help pure ice formation. The average distribution coefficient of sucrose in ice layer formed from sucrose solution does not appear to be affected by the addition of potato starch. However, the average distribution coefficient of potato starch in ice layer formed from suspension is influenced by sucrose concentration quite significantly. [source]


    JOURNAL OF PHYCOLOGY, Issue 4 2003
    Michael J. Higgins
    Atomic force microscopy (AFM) is used to investigate the topography and material properties of the mucilage layer of live cells of three benthic diatoms, the marine species Crasepdostauros australis E. J. Cox and Nitzschia navis-varingica Lundholm et Moestrup and the freshwater species Pinnularia viridis (Nitzsch) Ehrenberg. Contrary to previous studies, we show that this surface mucilage layer displays unique nanostructural features. In C. australis, tapping mode images revealed a soft mucilage layer encasing the silica cell wall, consisting of a smooth flat surface that was interrupted by regions with groove-like indentations, whereas force measurements revealed the adhesive binding of polymer chains. The elastic responses of these polymer chains, as they were stretched during force measurements, were successfully fitted to the worm-like chain model, indicating the stretching of mostly single macromolecules from which quantitative information was extracted. In P. viridis, tapping mode images of cells revealed a mucilage layer that had the appearance of densely packed spheres, whereas force measurements exhibited no adhesion. In N. navis-varingica, tapping mode images of the outer surface of this cell in the girdle region revealed the absence of a mucilage layer, in contrast to the other two species. In addition to these topographic and adhesion studies, the first quantitative measurement of the elastic properties of microalgal extracellular polymeric substance is presented and reveals significant spatial variation in the C. australis and P. viridis mucilage layers. This study highlights the capacity of AFM in elucidating the topography and mechanical properties of hydrated microalgal extracellular polymeric substance on a nanoscale. [source]


    ARCHAEOMETRY, Issue 2 2010
    The geochemical and engineering geological properties of the tuffs used in the rock-cut cliff tombs of the Etruscan necropolis of Norchia were investigated to evaluate their susceptibility to different weathering agents and confirm their origin. For the first time, materials were characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT,IR), thermogravimetric analyses (TGA, DGA and DTG), scanning electron microscopy (SEM,EDS) and energy-dispersive X-ray fluorescence (ED,XRF), and their different origins confirmed. Tests of material properties indicate that both tuffs are poorly durable, but one of them is less susceptible to weathering. Although tombs made with the more resistant material show limited surface weathering, they undergo severe structural damage because of stress release and plant root infiltration. This, combined with the microclimatic conditions established inside river canyons, can trigger rock falls, leading ultimately to the complete destruction of these tombs. [source]


    ABSTRACT Peanut oil migrates to the outer surface during roasting, where it comes into contact with oxygen, leading to the oxidation reactions. Because of its cleaning effect, power ultrasound (sonication) was used for removing surface lipid of roasted peanuts. Georgia green runner-type peanuts were roasted at 178C for 15 min. Roasted peanuts were subjected to lipid extraction in n-hexane by sonication. Fluorescent and electron scanning micrographs revealed that the surface of sonicated peanuts was free of oil stains, as opposed to that of freshly roasted peanuts. These results showed that power ultrasound could remove the lipids from peanut surfaces very effectively. Details of microstructure of sonicated peanuts as was observed using scanning electron microscope reveal that 10 min sonication was sufficient to extract most of the lipids on the roasted peanut surfaces. Fluorescence and scanning electron microscopy are useful in peanut analysis because they can detect lipids in low concentration. PRACTICAL APPLICATIONS There is increasing interest of quick procedures to examine the surfaces of roasted peanut samples after undergoing treatments, such as removal of lipids. This research demonstrated the significant use of fluorescent and scanning electron microscopes to quickly study the extent of lipid removal from the surface of roasted peanuts after power ultrasound treatment (sonication). [source]


    ABSTRACT Length-scale and area-scale analyses, two of the scale-sensitive fractal analyses performed by the software Surfrax, were used to study food surfaces measured with a scanning laser microscope (SLM). The SLM measures surfaces, or textures (i.e., acquires topographical data as a collection of heights as a function of position), at a spatial and vertical resolution of 25 ,m. The measured textures are analyzed by using linear and areal tiling (length-scale and area-scale analysis) and by conventional statistical analyses. Area-scale and length-scale fractal complexities (Lsfc and Asfc) and the smooth-rough crossover (SRC) are derived from the scale-sensitive fractal analyses. Both measures proved adequate to quantify and differentiate surfaces of foods (e.g., chocolate and a slice of bread), which were smooth or porous to the naked eye. Surfaces generated after frying of potato products (e.g., potato chips and French fries) had similar values of Asfc and SRC, and larger (implying more complex and rougher surfaces) than those of the raw potato. Variability of surface texture characterization parameters as a function of the size of the measured region was used in selecting the size of the measured regions for further analysis. The length-scale method of profile analysis (also called the Richardson or compass method) was useful in determining the directionality or lay of the anisotropic texture on food surfaces. [source]


    C. Fischer
    The fluvial-aeolian Rotliegend succession exposed in a quarry near Magdeburg (Flechtinger Höhenzug, Northern Germany) is an analogue for deeply-buried gas-bearing Rotliegend sandstones in the Southern Permian Basin. The spatial configuration of bounding surfaces within this succession was reconstructed with reference to twelve profiles with 926 sample points. Generally sub-horizontal interdune migration surfaces were surveyed, and the areal extent of small-scale superimposition surfaces and the thicknesses of intervening strata were measured. Based on these observations and also on the extent of different lithofacies types and on corresponding porosity and permeability data, a 3D lithofacies model (including bounding surface configurations) incorporating porosity and radial permeability was created using PETRELTÔ software. In the quarry, aeolian sandstones approximately 12 m thick (,, 5-11 vol. %, ,radial, 0.01-10mD) are separated into a number of tabular bed sets by sub-horizontal interdune migration surfaces. The surfaces are often associated with thin pelitic intervals with low permeabilities which originate from deflation and sheet flow events. Aeolian deposits consist mainly of two lithotypes: low-angle cross-bedded, and steeply cross-bedded medium-grained sandstones. Superimposition surfaces occur at the base of the low-angle cross-bedded sandstone bodies. The highest porosities and permeabilities occur within the steeply cross-bedded sandstones, reflecting intense eodiagenetic calcite and quartz cementation with subsequent calcite dissolution. The low-angle cross-bedded sandstones may act as flow baffles. This outcrop-derived, high resolution model may contribute to a better understanding of the subsurface architecture and reservoir properties of aeolian-fluvial successions. Taking into consideration the centimetre- to metre-scaled inhomogeneities observed at outcrop, lithotype modelling with reference to the occurrence of bounding surfaces may help to predict how similar reservoir rocks are partitioned. [source]


    ART HISTORY, Issue 3 2005
    Mechthild Fend
    This essay argues for the shared quality of skin and painting as signifying surfaces. When representing the surface of the body the artist engages with questions about the borders of the body and relations between the interior and the exterior. Portraits by Jacques-Louis David and Jean-Auguste-Dominique Ingres are considered in relation to several discursive fields: medical definitions of skin from the Enlightenment, nineteenth-century artistic anatomy and art theory. While David's rendering of skin is understood in terms of Xavier Bichat's definition of skin as a ,limite sensitive', the hermetically sealed and opaque skin of Ingres's figures negates contemporary notions of skin as a communicative membrane. Scientific knowledge notwithstanding, these very different approaches to the representation of skin may be seen as reflecting upon different ways to produce meaning as well as different conceptions of the body. Mechthild Fend is a research scholar at the Max Planck Institute for the History of Science in Berlin, where she is working on a project on the history and representation of skin in late eighteenth- and nineteenth-century France. Her recent books deal with the representation of masculinity: Männlichkeit im Blick. Visuelle Inszenierungen in der Kunst seit der Frühen Neuzeit (co-edited with Marianne Koos, Cologne, 2004), and Grenzen der Männlichkeit. Der Androgyn in der französischen Kunst und Kunsttheorie Zwischen Aufkl.arung und Restauration (Berlin, 2003). [source]

    The Perspective Silhouette of a Canal Surface

    Ku-Jin Kim
    We present an efficient and robust algorithm for parameterizing the perspective silhouette of a canal surface and detecting each connected component of the silhouette. A canal surface is the envelope of a moving sphere with varying radius, defined by the trajectoryC(t)of its center and a radius functionr(t). This moving sphere,S(t), touches the canal surface at a characteristic circleK(t). We decompose the canal surface into a set of characteristic circles, compute the silhouette points on each characteristic circle, and then parameterize the silhouette curve. The perspective silhouette of the sphereS(t)from a given viewpoint consists of a circleQ(t); by identifying the values oftat whichK(t)andQ(t)touch, we can find all the connected components of the silhouette curve of the canal surface. ACM CSS: I.3.7 Computer Graphics,Three Dimensional Graphics and Realism [source]

    Space-Charge Limited Current from Plasma-Facing Material Surface

    S. Takamura
    Abstract We have derived an exact theoretical expression for the space-charge limited current from the solid surfaces adjacent to plasmas that is applicable for an arbitrary sheath voltage. Our expression shows that the spacecharge limited current tends to saturate with the sheath voltage. This new formula is evaluated by 1-D Particle in Cell (PIC) simulation and experiment, and is in a good agreement with the simulation and experimental results. We have also obtained an analytical equation fitted to the new formula based on conventional Child-Langmuir formula by taking into account a more sophisticated dependence of the electrode potential and the plasma density through the effect of Debye shielding and a sheath expansion due to increased voltage across the sheath. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Diagnostic potential of serum protein pattern in Type 2 diabetic nephropathy

    DIABETIC MEDICINE, Issue 12 2007
    Y-H. Yang
    Abstract Aims Microalbuminuria is the earliest clinical sign of diabetic nephropathy (DN). However, the multifactorial nature of DN supports the application of combined markers as a diagnostic tool. Thus, another screening approach, such as protein profiling, is required for accurate diagnosis. Surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) is a novel method for biomarker discovery. We aimed to use SELDI and bioinformatics to define and validate a DN-specific protein pattern in serum. Methods SELDI was used to obtain protein or polypeptide patterns from serum samples of 65 patients with DN and 65 non-DN subjects. From signatures of protein/polypeptide mass, a decision tree model was established for diagnosing the presence of DN. We estimated the proportion of correct classifications from the model by applying it to a masked group of 22 patients with DN and 28 non-DN subjects. The weak cationic exchange (CM10) ProteinChip arrays were performed on a ProteinChip PBS IIC reader. Results The intensities of 22 detected peaks appeared up-regulated, whereas 24 peaks were down-regulated more than twofold (P < 0.01) in the DN group compared with the non-DN groups. The algorithm identified a diagnostic DN pattern of six protein/polypeptide masses. On masked assessment, prediction models based on these protein/polypeptides achieved a sensitivity of 90.9% and specificity of 89.3%. Conclusion These observations suggest that DN patients have a unique cluster of molecular components in serum, which are present in their SELDI profile. Identification and characterization of these molecular components will help in the understanding of the pathogenesis of DN. The serum protein signature, combined with a tree analysis pattern, may provide a novel clinical diagnostic approach for DN. [source]

    Surface and phonological subtypes of adult developmental dyslexia

    DYSLEXIA, Issue 3 2002
    Claire Zabell
    Abstract In order to assess the efficacy of phonological versus surface dyslexia subtyping within an adult dyslexic population, 45 adult dyslexics were assessed on the Castles and Coltheart (1993) irregular word and non-word reading tasks. Based on the performance of a matched group of 28 non-dyslexics, between 62 and 75% of the dyslexics were divided into phonological and surface subtypes. Phonological dyslexics were those individuals who presented evidence of relatively poor or inefficient non-word reading, whereas the surface dyslexics were those who indicated relative difficulties with irregular word reading. The proportions of dyslexics within each subtype varied according to the use of accuracy-based or latency-based procedures, but were consistent with previous findings with children. Subsequent comparisons between the groups on measures of phonological processing, lexical access and word knowledge/recognition indicated few differences between the two subtypes and, in particular, no differences on measures of phonological ability. The lack of observed differences on such measures casts doubt on the efficacy of this procedure for explaining individual differences amongst adult dyslexics and as a practical procedure for diagnosis and intervention. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Double Modification of Electrode Surface for the Selective Detection of Epinephrine and Its Application to Flow Injection Amperometric Analysis

    ELECTROANALYSIS, Issue 22 2009
    Guang-Ri Xu
    Abstract A glassy carbon electrode having two polymer layers has been applied to selectively detect epinephrine. The inner layer formed by electropolymerization of macrocyclic nickel complex functioned as an electrocatalyst for epinephrine oxidation and the outer layer composed of hydrolyzed polyurethane ,-benzyl L -glutamate as a screening layer. Differential pulse voltammetry showed almost 100% recovery of epinephrine even in 100-fold excess of interferents. When applied to a dual glassy carbon electrode as an amperometric detector in flow injection analysis, a linear response over 0.1,,M and 10,,M was obtained. Recovery tested for 5-fold diluted human urine samples was 97.5%. [source]

    Voltammetric Studies of the Interactions Between Ferrocene-Labeled Glutathione and Proteins in Solution or Immobilized onto Surface

    ELECTROANALYSIS, Issue 16 2009
    Yong Peng
    Abstract Glutathione (GSH) tagged with a ferrocene (Fc) label at its C-terminal was synthesized via coupling ferrocenyl amine to glutathione using o -(benzotriazol-1-yl)- N,N,N,,N, -tetramethyluronium (HBTU)/1-hydroxybenzotrizole (HOBt). The presence of Fc yielded well defined voltammetric signals, rendering the Fc-tagged GSH (GSH-Fc) suitable for electrochemical studies of GSH binding to other biological species. The interaction of GSH-Fc with bovine serum albumin (BSA) was investigated, and a binding ratio of 1.41±0.06 (GSH-Fc/BSA) and an affinity constant Ka of 6.53±2.01×106,M,1 were determined. These results compare well with those measured by fluorescence using untagged GSH, suggesting that the attachment of Fc to GSH does not significantly perturb the GSH structure and binding behavior. By contrasting the binding behavior to several compounds that are known to conjugate to different domains of BSA, the voltammetric study confirmed that GSH-Fc binds at subdomain IIA of BSA with high affinity. The versatility of GSH-Fc for studying GSH binding to surface-confined proteins was also demonstrated with the GSH binding to electroinactive Zn-metallothionein (Zn7 -MT) through hydrogen binding at the region between the Zn7 -MT , and , domains. [source]

    Quantitative Studies of Metal Ion Adsorption on a Chemically Modified Carbon Surface: Adsorption of Cd(II) and Hg(II) on Glutathione Modified Carbon

    ELECTROANALYSIS, Issue 8 2009
    Poobalasingam Abiman
    Abstract The adsorption behavior of model toxic metal cations namely Cd(II) and Hg(II) on carbon surfaces chemically modified by glutathione was investigated as a function of the concentration of Cd2+ and Hg2+ ions, time and the amount of modified carbon used. Square wave and linear sweep anodic stripping voltammetry was used to monitor the uptake of Cd(II) and Hg(II) ions respectively. Kinetic and adsorption isotherm studies reveal that both Cd(II) and Hg(II) ions undergo similar large adsorption with the modified glutathione carbon material (Glu-carbon). [source]

    Dramatic Effects of Ionic Liquid on Platinum Electrode Surface and Electron-Transfer Rates of meso -Tetraphenylporphyrins

    ELECTROANALYSIS, Issue 12 2006
    Afsaneh Safavi
    Abstract The effect of addition of a room temperature ionic liquid, 1-butyl-3-methyl imidazolium hexafluorophosphate [bmim][PF6], on the electrochemical behavior of different free-base para-substituted meso -tetraphenylporphyrins in dichloromethane solution has been studied using cyclic voltammetric technique. It has been found that the ionic liquid has the ability to regenerate platinum electrode surface and improves the reversibility of electrode processes. This has been true for the case of all the porphyrins studied. [source]

    Alfentanil-Induced Epileptiform Activity: A Simultaneous Surface and Depth Electroencephalographic Study in Complex Partial Epilepsy

    EPILEPSIA, Issue 2 2001
    J. Ross
    Summary: ,Purpose: Alfentanil is a high potency mu opiate receptor agonist commonly used during presurgical induction of anesthesia. This and other opiate receptor agonists have demonstrated proconvulsant effects in animals, but these properties have been less consistently demonstrated in humans. Most human scalp EEG studies have failed to demonstrate induction of epileptiform activity with these agents, which is inconsistent with findings using intracranial EEG. Simultaneous scalp and depth EEG recordings have yet to be performed in this setting. The relationship between opiate dose and proconvulsant activity is unclear. Methods: Simultaneous scalp and depth electrode recordings were performed on five patients with complex partial epilepsy (CPE) who underwent alfentanil anesthesia induction before depth electrode removal. Consecutive equal bolus doses of alfentanil were administered to each patient according to strict time intervals so as to assess their correlation with any induced epileptiform activity. Results: Epileptiform activity was induced by alfentanil in three of five patients. Two of these patients had electrographic seizures. Epileptiform activity was only detected from the depth electrodes, occurring within 2 min of the first bolus dose in all three cases. Further increase or spread of epileptiform activity did not occur despite cumulative bolus doses of alfentanil. Conclusions: Alfentanil is proconvulsant in patients with CPE. Induced seizures may be subclinical and lack a scalp EEG correlate. There is a complex dose,response relationship. Alfentanil induction of anesthesia should be approached with caution in patients with CPE. [source]

    Stable Non-Covalent Large Area Patterning of Inert Teflon-AF Surface: A New Approach to Multiscale Cell Guidance,

    Francesco Valle
    Micro- and nano-patterning of cell adhesion proteins is demonstrated to direct the growth of neural cells, viz. human neuroblastoma SHSY5Y, at precise positions on a strongly antifouling substrate of technolological interest. We adopt a soft-lithographic approach with oxygen plasma modified PDMS stamps to pattern human laminin on Teflon-AF films. These patterns are based on the interplay of capillary forces within the stamp and non-covalent intermolecular and surface interactions. Remarkably, they remain stable for several days upon cell culture conditions. The fabrication of substrates with adjacent antifouling and adhesion-promoting regions allows us to reach absolute spatial control in the positioning of neuroblastoma cells on the Teflon-AF films. This patterning approach of a technologically-relevant substrate can be of interest in tissue engineering and biosensing. [source]

    Bi-Stable Adhesion of a Surface with a Dimple

    Robert M. McMeeking
    In this paper, we propose a new adhesive system of dimpled surfaces. The principle is derived from a contact mechanics model. The material is assumed to be linear elastic and isotropic, and attraction between the surfaces of the half-spaces is modeled via the concept of a specific adhesion energy. It is found that large and small detachments are unstable and will either grow or shrink spontaneously when their sizes are perturbed. It is shown that this phenomenon can lead to a new bi-stable adhesive system in which weak adhesion can be converted to strong adhesion by the application of pressure. [source]

    Construction of Polyethyleneimine-,-cyclodextrin/pDNA Multilayer Structure for Improved In Situ Gene Transfection,

    Yan Hu
    This study reports in situ gene delivery from gene-functionalized poly(D,L -lactic acid) (PDLLA, Mw of around 2.0,×,105,g,mol,1) films, which were constructed via layer-by-layer (LbL) assembly technique with low molecular weight polyethylenimine-,-cyclodextrin (PEI-CD) conjugate and plasmid DNA (pDNA). PEI-CD was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR), respectively. The buildup of multilayered PEI-CD/pDNA pairs onto PDLLA films was monitored with contact angle measurements and UV,Vis spectrometer, respectively. A sustained release of pDNA from multilayered films was observed for 28,h. The mechanism of in situ gene delivery on PDLLA film was investigated in this study as well. Spherical PEI-CD/pDNA complexes were formed and released following the deconstruction of multilayered films, which was confirmed by transmission electron microscopy (TEM) and gel electrophoresis, respectively. Surface mediated in situ gene transfection was achieved when culturing hepatoma G2 (HepG2) and human embryonic kidney 293 (HEK293) onto PEI-CD/pDNA multilayered films. Furthermore, PEI-CD improved the gene transfection efficiency when compared with that of PEI. Such gene-functionalized biomaterial reported here has potential application in tissue engineering and implant technology. [source]

    Crystal Growth of the Metal,Organic Framework Cu3(BTC)2 on the Surface of Pulp Fibers

    Pia Küsgens
    In situ growth of highly porous metal,organic frameworks (MOFs) in the presence of pulp fibers results in high surface area MOF/textile composites. Such a carrier concept is indispensable for any industrial application of MOFs. [source]

    Nanoscale Conducting Channels at the Surface of Organic Semiconductors Formed by Decoration of Molecular Steps with Self-Assembled Molecules

    Bumsu Lee
    Abstract Under certain conditions, self-assembling molecules preferentially bind to molecular steps at the surface of crystalline organic semiconductors, inducing a strong local doping effect. This creates macroscopically long conducting paths of nanoscale width (a single crystalline analogue of organic nanowires) that can span distances of up to 1,cm between electrical contacts. The observed effect of molecular step decoration opens intriguing possibilities for visualization, passivation, and selective doping of surface and interfacial defects in organic electronic devices and provides a novel system for research on nanoscale charge transport in organic semiconductors. In addition, this effect sheds light on the microscopic origin of nucleation and growth of self-assembled monolayers at organic surfaces. It can also have implications in electronic patterning, nanoscale chemical sensors, integrated interconnects and charge-transfer interfaces in organic transistors and solar cells. [source]

    Self-Organization of a Highly Integrated Silicon Nanowire Network on a Si(110),16,×,2 Surface by Controlling Domain Growth

    Ie-Hong Hong
    Abstract Here, bottom-up nanofabrication for the two-dimensional self-organization of a highly integrated, well-defined silicon nanowire (SiNW) mesh on a naturally-patterned Si(110),16,×,2 surface by controlling the lateral growths of two non-orthogonal 16,×,2 domains is reported. This self-ordered nanomesh consists of two crossed arrays of parallel-aligned SiNWs with nearly identical widths of 1.8,2.5,nm and pitches of 5.0,5.9,nm, and is formed over a mesoscopic area of 300,×,270,nm2 so as to show a high integration density in excess of 104,µm,2. These crossed SiNWs exhibit semiconducting character with an equal band gap of ,0.95,eV as well as unique quantum confinement effect. Such an ultrahigh-density SiNW network can serve as a versatile nanotemplate for nanofabrication and nanointegration of the highly-integrated metal-silicide or molecular crossbar nanomesh on Si(110) surface for a broad range of device applications. Also, the multi-layer, vertically-stacked SiNW networks can be self-assembled through hierarchical growth, which opens the possibility for creating three-dimensionally interconnected crossbar circuits. The ability to self-organize an ultrahigh-density, functional SiNW network on a Si(110) surface represents a simple step toward the fabrication of highly-integrated crossbar nanocircuits in a very straightforward, fast, cost-effective, and high throughput process. [source]

    Fabrication of a Superhydrophobic Surface from a Smectic Liquid-Crystal Defect Array

    Yun Ho Kim
    Abstract A novel fabrication method is developed for the preparation of superhydrophobic surfaces. The procedure uses focal conic structures of semi-fluorinated smectic liquid crystals (LCs) whose periodic toric focal conic domains (TFCDs) are prepared on a surface modified substrate. Reactive ion etching (RIE) on the periodic TFCD surface leads to a superhydrophobic surface with a water contact angle of ,160° and a sliding angle of ,2° for a 10,µL water droplet. The results show that this phenomenon is due to the development of a dual-scale surface roughness arising from the nanoscale protuberance caused by applying the RIE process to the top of the microscale TFCD arrays. The unique surface behavior is further verified by demonstrating that RIE on a flat lamellar liquid crystal film, in which the director is aligned parallel with surface, results in a relatively low hydrophobicity as compared to when periodic TFCDs are subjected to REI. The observations made in this publication suggest that a new approach exists for selecting potential candidates of superhydrophic surface formation based on spontaneous self-assembly in smectic liquid-crystalline materials. [source]

    Surface Cooling for Rapid Induction of Mild Hypothermia After Cardiac Arrest: Design Determines Efficacy

    Thomas Uray MD
    Abstract Objectives:, Recently, a novel cooling pad was developed for rapid induction of mild hypothermia after cardiac arrest. The aim of this study was to evaluate the cooling efficacy of three different pad designs for in-hospital cooling. Methods:, Included in this prospective interventional study were patients with esophageal temperature (Tes) > 34°C on admission. The cooling pad consists of multiple cooling units, filled with a combination of graphite and water, which is precooled to ,18°C (design A) or to ,9°C (designs B and C) before use. The designs of the cooling pad differed in number, shape, and thickness of the cooling units, with weights of 9.7 kg (design A), 5.3 kg (design B), and 6.2 kg (design C). All three designs were tested in sequential order and were changed according to the results found in the previous trial. Cooling was started after admission until Tes = 34°C, when the cooling pad was removed. The target temperature of Tes = 32,34°C was maintained for 24 hours. Data are presented as medians and interquartile ranges (IQRs = 25%,75%) or proportions. Results:, Cooling rates were 3.4°C/hour (IQR = 2.5,3.7) with design A (n = 12), 2.8°C/hour (IQR = 1.6,3.3) with design B (n = 7), and 2.9°C/hour (IQR = 1.9,3.6) with design C (n = 10; p = 0.5). To reach 34°C, the cooling pad had to be exchanged with a new one due to melting and therefore depleting cooling capacity in three patients with design A, in five patients with design B, and in no patient with design C (p = 0.004). Conclusions:, With adequate design and storage temperature, the cooling pad proved to be efficient for rapid in-hospital cooling of patients resuscitated from cardiac arrest. ACADEMIC EMERGENCY MEDICINE 2010; 17:360,367 © 2010 by the Society for Academic Emergency Medicine [source]

    Stone artifact scatters in western NSW, Australia: Geomorphic controls on artifact size and distribution

    Patricia Fanning
    Surface scatters of Aboriginal stone artifacts have been exposed in many parts of inland Australia by accelerated erosion that followed the introduction of pastoralism by European settlers in the 19th century. This paper reports on a set of techniques developed to investigate and quantify the effects of these post-discard disturbance processes in Sturt National Park in northwest NSW, Australia. Backwards, stepwise, linear regression showed the influence of geomorphic parameters such as slope gradient, elevation, landform, and contemporary surface processes on artifact distribution, with artifact maximum dimension as the dependent variable. The results indicate that, even at low gradients, artifact size and slope angle are significantly related, but that the variance in maximum dimension explained by gradient is very low. Similar results were found for the other geomorphic variables. We conclude that artifact movement by surface wash across these surfaces is unlikely to significantly affect artifact distribution. While vertically conflated surface scatters do not preserve "living floors" in a short-term, functional sense, their apparent horizontal integrity allows investigation of the long-term use of place by hunter-gatherer people in the past. Insofar as assemblage integrity is important for assessing site significance in the heritage management industry, our methods provide a means for assessing the degree to which a site has been damaged by water flow. © 2001 John Wiley & Sons, Inc. [source]

    A Surface-Based Approach to Measuring Spatial Segregation

    David O'Sullivan
    Quantitative indices of residential segregation have been with us for half a century, but suffer significant limitations. While useful for comparison among regions, summary indices fail to reveal spatial aspects of segregation. Such measures generally consider only the population mix within zones, not between them. Zone boundaries are treated as impenetrable barriers to interaction between population subgroups, so that measurement of segregation is constrained by the zoning system, which bears no necessary relation to interaction among population subgroups. A segregation measurement approach less constrained by the chosen zoning system, which enables visualization of segregation levels at the local scale and accounts for the spatial dimension of segregation, is required. We propose a kernel density estimation approach to model spatial aspects of segregation. This provides an explicitly geographical framework for modeling and visualizing local spatial segregation. The density estimation approach lends itself to development of an index of spatial segregation with the advantage of functional compatibility with the most widely used index of segregation (the dissimilarity index D). We provide a short review of the literature on measuring segregation, briefly describe the kernel density estimation method, and illustrate how the method can be used for measuring segregation. Examples using a simulated landscape and two empirical cases in Washington, DC and Philadelphia, PA are presented. [source]

    Self-Assembled Robust Dipeptide Nanotubes and Fabrication of Dipeptide-Capped Gold Nanoparticles on the Surface of these Nanotubes,

    Samit Guha
    Abstract Three water-soluble dipeptides containing N-terminally located , -alanine residue and C-terminally located , -amino acid residues (, -Ala- L -Xaa, Xaa,=,Val/Ile/Phe) form robust crystalline nanotubes. These dipeptide nanotubes contain a common motif, a hybrid of ,,, -amino acids, which are stable against heat up to 80,°C, a wide range of pH (2,10), and proteolytic degradation. These robust crystalline dipeptide nanotubes are used as a template for fabricating dipeptide-capped gold nanoparticles on their outer surfaces. This is an easy way to develop nanotube/nanoparticle hybrid materials under mild conditions. [source]

    Calcium Isotopic Composition of Various Reference Materials and Seawater

    Dorothee Hippler
    composition isotopique du calcium; eau de mer; paléocéanographie; NIST SRM 915a A compilation of ,44/40Ca (,44/40Ca) data sets of different calcium reference materials is presented, based on measurements in three different laboratories (Institute of Geological Sciences, Bern; Centre de Géochimie de la Surface, Strasbourg; GEOMAR, Kiel) to support the establishment of a calcium isotope reference standard. Samples include a series of international and internal Ca reference materials, including NIST SRM 915a, seawater, two calcium carbonates and a CaF2 reference sample. The deviations in ,44/40Ca for selected pairs of reference samples have been defined and are consistent within statistical uncertainties in all three laboratories. Emphasis has been placed on characterising both NIST SRM 915a as an internationally available high purity Ca reference sample and seawater as representative of an important and widely available geological reservoir. The difference between ,44/40Ca of NIST SRM 915a and seawater is defined as -1.88 O.O4%o (,44/42CaNISTSRM915a/Sw= -0.94 0.07%o). The conversion of values referenced to NIST SRM 915a to seawater can be described by the simplified equation ,44/40CaSa/Sw=,44/40CaSa/NIST SRM 915a - 1.88 (,44/42CaSa/Sw=,44/42CaSa/NIST SRM 915a - 0.94). We propose the use of NIST SRM 915a as general Ca isotope reference standard, with seawater being defined as the major reservoir with respect to oceanographic studies. On présente ici une compilation de données de ,44/40Ca (,44/42Ca) obtenues sur différents matériaux de référence, à partir d'analyses effectuées dans trois laboratoires (Institute of Geological Sciences, Berne; Centre de Géochimie de la Surface, Strasbourg; GEOMAR, Kiel) dans le but de définir des matériaux standards de référence pour isotopie du calcium. Les échantillons comprenaient une série de matériaux standards, internes et internationaux, de référence pour le calcium, avec NIST SRM 915a, l'eau de mer, deux carbonates de calcium, et un échantillon de CaF2 de référence. Les déviations en ,44/40Ca pour des paires sélectionnées d'échantillons de référence ont été définies et sont en accord, compte tenu des incertitudes statistiques, entre les trois laboratoires. L'accent a été mis sur la nécessité de caractériser à la fois NIST SRM 915a, en tant que matériau de référence très pur, internationalement disponible, et l'eau de mer comme représentant d'un réservoir géologique très important et disponible partout. La différence entre les ,44/40Ca de NIST SRM 915a et de l'eau de mer est définie comme étant de -1.88 0.04%0,44/42CaNIST SRM 915a/Sw= -0.94 0.07%0). La conversion des données référencées par rapport à NIST SRM 915a à la référence -eau de mer- se fait selon l'équation simplifiée équation ,44/40CaSa/Sw=,44/40CaSa/NIST SRM 915a - 1.88 (,44/42Ca Sa/Sw=,44/42CaSa/NIST SRM 915a - 0.94). Nous proposons l'utilisation de NIST SRM 915a comme matériau standard de référence pour les isotopes de Ca, avec l'eau de mer comme réservoir majeur adapté aux études océanographiques. [source]