Direct Detection and Measurement of Electron Relays in a Multicentered Enzyme:  Voltammetry of Electrode-Surface Films ofE. coliFumarate Reductase, an Iron−Sulfur Flavoprotein

1997 ◽  
Vol 119 (48) ◽  
pp. 11628-11638 ◽  
Author(s):  
Hendrik A. Heering ◽  
Joel H. Weiner ◽  
Fraser A. Armstrong
Keyword(s):  
Electrode Surface ◽  
Direct Detection ◽  
Surface Films ◽  
Iron Sulfur ◽  
Electron Relays

Specular reflection spectroscopy of electrode surface films

1970 ◽  
Vol 4 ◽  
pp. 99 ◽  
Author(s):  
J. D. E. McIntyre ◽  
D. M. Kolb
Keyword(s):  
Electrode Surface ◽  
Specular Reflection ◽  
Surface Films ◽  
Reflection Spectroscopy

Losses in Electrode Surface Films in Gas Dielectric Capacitors

1979 ◽  
Vol 28 (4) ◽  
pp. 279-284 ◽  
Author(s):  
Eddy So ◽  
John Q. Shields
Keyword(s):  
Electrode Surface ◽  
Surface Films

Detection and Characterization of earth-like Planets

1997 ◽  
Vol 161 ◽  
pp. 299-311 ◽  
Author(s):  
Jean Marie Mariotti ◽  
Alain Léger ◽  
Bertrand Mennesson ◽  
Marc Ollivier
Keyword(s):  
Direct Detection ◽  
Contrast Ratio ◽  
Angular Size ◽  
Physical Nature ◽  
Major Axis ◽  
Infrared Emission ◽  
Space Technology ◽  
Semi Major Axis ◽  
Earth Like Planets ◽  
Visible Wavelengths

AbstractIndirect methods of detection of exo-planets (by radial velocity, astrometry, occultations,...) have revealed recently the first cases of exo-planets, and will in the near future expand our knowledge of these systems. They will provide statistical informations on the dynamical parameters: semi-major axis, eccentricities, inclinations,... But the physical nature of these planets will remain mostly unknown. Only for the larger ones (exo-Jupiters), an estimate of the mass will be accessible. To characterize in more details Earth-like exo-planets, direct detection (i.e., direct observation of photons from the planet) is required. This is a much more challenging observational program. The exo-planets are extremely faint with respect to their star: the contrast ratio is about 10−10at visible wavelengths. Also the angular size of the apparent orbit is small, typically 0.1 second of arc. While the first point calls for observations in the infrared (where the contrast goes up to 10−7) and with a coronograph, the latter implies using an interferometer. Several space projects combining these techniques have been recently proposed. They aim at surveying a few hundreds of nearby single solar-like stars in search for Earth-like planets, and at performing a low resolution spectroscopic analysis of their infrared emission in order to reveal the presence in the atmosphere of the planet of CO H2O and O3. The latter is a good tracer of the presence of oxygen which could be, like on our Earth, released by biological activity. Although extremely ambitious, these projects could be realized using space technology either already available or in development for others missions. They could be built and launched during the first decades on the next century.

Surface Films on Zircaloy-2 Samples Cracked in Neutral Aqueous NaCl by Stress Corrosion

1973 ◽  
Vol 31 ◽  
pp. 46-47
Author(s):  
R.A. Ploc
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Film Thickness ◽  
Stress Corrosion ◽  
Zirconium Dioxide ◽  
Surface Film ◽  
Surface Films ◽  
Continuous Layer ◽  
Transmission Electron ◽  
Product Film

Samples of low-nickel Zircaloy-2 (material MLI-788-see(1)), when anodically polarized in neutral 5 wt% NaCl solutions, were found to be susceptible to pitting and stress corrosion cracking. The SEM revealed that pitting of stressed samples was occurring below a 2000Å thick surface film which behaved differently from normal zirconium dioxide in that it did not display interference colours. Since the initial film thickness was approximately 65Å, attempts were made to examine the product film by transmission electron microscopy to deduce composition and how the corrosion environment could penetrate the continuous layer.

TEM studies of amorphization processes and amorphous structures

1988 ◽  
Vol 46 ◽  
pp. 448-449
Author(s):  
T. E. Mitchell ◽  
R. B. Schwarz
Keyword(s):  
Amorphous Materials ◽  
Fission Products ◽  
Rapid Quenching ◽  
Surface Films ◽  
List Type ◽  
Oxide Glasses ◽  
Crystalline Materials ◽  
Amorphous Structures ◽  
Amorphous Surface ◽  
Interfacial Films

Traditional oxide glasses occur naturally as obsidian and can be made easily by suitable cooling histories. In the past 30 years, a variety of techniques have been discovered which amorphize normally crystalline materials such as metals. These include [1-3]:Rapid quenching from the vapor phase.Rapid quenching from the liquid phase.Electrodeposition of certain alloys, e.g. Fe-P.Oxidation of crystals to produce amorphous surface oxide layers.Interdiffusion of two pure crystalline metals.Hydrogen-induced vitrification of an intermetal1ic.Mechanical alloying and ball-milling of intermetal lie compounds.Irradiation processes of all kinds using ions, electrons, neutrons, and fission products.We offer here some general comments on the use of TEM to study these materials and give some particular examples of such studies.Thin specimens can be prepared from bulk homogeneous materials in the usual way. Most often, however, amorphous materials are in the form of surface films or interfacial films with different chemistry from the substrates.

Corrections for surface films in microanalysis by EDS and EELS

1992 ◽  
Vol 50 (2) ◽  
pp. 1230-1231
Author(s):  
J. Bentley ◽  
E. A. Kenik
Keyword(s):  
Hydrocarbon Contamination ◽  
Specimen Preparation ◽  
Surface Films ◽  
Ion Milling ◽  
Preferential Sputtering ◽  
Electron Energy Loss Spectrometry ◽  
Composition Determination ◽  
Analytical Electron ◽  
First Order Correction ◽  
Electron Energy Loss

Common artifacts on analytical electron microscope (AEM) specimens prepared from bulk materials are surface films with altered structure and composition that result from electropolishing, oxidation, hydrocarbon contamination, or ion milling (preferential sputtering or deposition of sputtered specimen or support material). Of course, the best solution for surface films is to avoid them by improved specimen preparation and handling procedures or to remove them by low energy ion sputter cleaning, a capability that already exists on some specialized AEMs and one that is likely to become increasingly common. However, the problem remains and it is surprising that surface films have not received more attention with respect to composition determination by energy dispersive X-ray spectrometry (EDS) and electron energy loss spectrometry (EELS).For EDS, an effective first-order correction to remove the contribution of surface films on wedge shaped specimens is to subtract from the spectrum of interest a spectrum obtained under identical conditions (probe current, diffracting conditions, acquisition live time) from a thinner region of the specimen.

Sampling and analysis of the air-water interface with SEM and EDS of microlayers

1989 ◽  
Vol 47 ◽  
pp. 1004-1005
Author(s):  
Randall W. Smith ◽  
John Dash
Keyword(s):  
Heavy Metals ◽  
Surface Microlayer ◽  
Surface Films ◽  
Water Interface ◽  
Physical Processes ◽  
Infrared Spectroscopic Analysis ◽  
Eds Analysis ◽  
Air Water Interface ◽  
Significant Area ◽  
Bulk Chemical

The structure of the air-water interface forms a boundary layer that involves biological ,chemical geological and physical processes in its formation. Freshwater and sea surface microlayers form at the air-water interface and include a diverse assemblage of organic matter, detritus, microorganisms, plankton and heavy metals. The sampling of microlayers and the examination of components is presently a significant area of study because of the input of anthropogenic materials and their accumulation at the air-water interface. The neustonic organisms present in this environment may be sensitive to the toxic components of these inputs. Hardy reports that over 20 different methods have been developed for sampling of microlayers, primarily for bulk chemical analysis. We report here the examination of microlayer films for the documentation of structure and composition.Baier and Gucinski reported the use of Langmuir-Blogett films obtained on germanium prisms for infrared spectroscopic analysis (IR-ATR) of components. The sampling of microlayers has been done by collecting fi1ms on glass plates and teflon drums, We found that microlayers could be collected on 11 mm glass cover slips by pulling a Langmuir-Blogett film from a surface microlayer. Comparative collections were made on methylcel1ulose filter pads. The films could be air-dried or preserved in Lugol's Iodine Several slicks or surface films were sampled in September, 1987 in Chesapeake Bay, Maryland and in August, 1988 in Sequim Bay, Washington, For glass coverslips the films were air-dried, mounted on SEM pegs, ringed with colloidal silver, and sputter coated with Au-Pd, The Langmuir-Blogett film technique maintained the structure of the microlayer intact for examination, SEM observation and EDS analysis were then used to determine organisms and relative concentrations of heavy metals, using a Link AN 10000 EDS system with an ISI SS40 SEM unit. Typical heavy microlayer films are shown in Figure 3.

A novel enzyme immunoassay for the direct detection of H. pylori antigens in stool

2001 ◽  
Vol 120 (5) ◽  
pp. A492-A493 ◽  
Author(s):  
E HAINDL ◽  
H BENESCH ◽  
A FINCK ◽  
V MUEHISTEIN ◽  
A LEODOLTER ◽  
...  
Keyword(s):  
Enzyme Immunoassay ◽  
Direct Detection ◽  
H Pylori
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