scholarly journals Röntgenspektroskopische Untersuchung der chemischen Bindung in Oxiden

1967 ◽  
Vol 22 (9) ◽  
pp. 1401-1407 ◽  
Author(s):  
Hans-Ulrich Chun ◽  
Dieter Hendel
Keyword(s):  
Fine Structure ◽  
Metal Atom ◽  
Short Wavelength ◽  
The Other ◽  
Main Line ◽  
Ionic Character ◽  
Long Wavelength ◽  
Short Wavelength Side ◽  
Oxygen Bond ◽  
Wavelength Side

This paper reports about the fine structure in the O—K-spectra of the oxides BeO, MgO, CaO, SrO, BaO, Sc2O5, Y2O3, La2O3, Sm2O3, Yb2O3, NiO and ZnO. The spectra show the satellite lines α3, α4, α5, α6 on the short wavelength side of the main line α1,2 and a shoulder β′ on its long wavelength side. The wavelengths of all lines depend on the nature of the oxide. For the positions of the lines Kα1.2 in the spectra no systematic relation to other data of the oxides is observed. On the other hand the distance of the a4-satellite from the α1,2-line decreases with increasing electronegativity of the metal atom in the oxide. This distance can be used as a measure for the ionic character of the metal-oxygen bond in these compounds.

Mass Loss from Stars

1977 ◽  
Vol 3 (2) ◽  
pp. 96-96
Author(s):  
Donald C. Morton
Keyword(s):  
Mass Loss ◽  
Radiation Field ◽  
Excited States ◽  
Short Wavelength ◽  
Hot Stars ◽  
Short Wavelength Side ◽  
Far Ultraviolet ◽  
Wavelength Side ◽  
Space Observations

The visual spectra of some hot stars, including P Cygni, have emission with associated absorption troughs ˜ 102 km s-1 on the short-wavelength side (Beals 1929, 1951). These P Cygni profiles are easily understood in terms of mass flowing away from the star. Later, rocket observations of the far-ultraviolet resonance lines (Morton 1967) showed that the phenomenon is rather common among hot stars and the velocity shifts could be from 1000 to 3000 km s-1, demonstrating that the mass must be escaping from the star. Resonance lines provide the strongest absorption in the shell where neither the density nor the radiation field is high enough to leave many ions in excited states. Since the ion stages likely to be present around a hot star have their resonance lines shortward of the atmospheric cutoff, space observations are essential in this investigation. Figure 1 shows the P Cygni profile of O VI in ς Pup obtained with Copernicus satellite spectrometer.

A Discussion on astronomy in the ultraviolet - Mass loss from the A-type supergiant α Cygni

1975 ◽  
Vol 279 (1289) ◽  
pp. 445-450 ◽  
Keyword(s):  
Mass Loss ◽  
Spectral Resolution ◽  
Short Wavelength ◽  
High Spectral Resolution ◽  
The Core ◽  
Short Wavelength Side ◽  
Wavelength Side

The Mg ii resonance lines in a Cygni (A2Ia) are studied from 22 spectral scans obtained by the experiment S59. The cores of the resonance lines are shifted by — 130 km/s and the short wavelength side of the core is shifted by about — 350 km/s. The lines are compared with predicted profiles in an expanding atmosphere. This comparison suggests a rate of mass loss of 3 x 10-10 ^®/year. The atmosphere seems to be accelerated up to a velocity of 300 km/s. The acceleration might be produced by the near-u.v. resonance lines of singly ionized metals. The observations of the near-u.v. spectrum of A-type supergiants with a high spectral resolution is recommended.

Processing of S-cone signals in the inner plexiform layer of the mammalian retina

2013 ◽  
Vol 31 (2) ◽  
pp. 153-163 ◽  
Author(s):  
KIYOHARU J. MIYAGISHIMA ◽  
ULRIKE GRÜNERT ◽  
WEI LI
Keyword(s):  
Ganglion Cell ◽  
Short Wavelength ◽  
Plexiform Layer ◽  
The Other ◽  
Current Understanding ◽  
Inner Plexiform Layer ◽  
Color Information ◽  
Long Wavelength ◽  
Mammalian Retina ◽  
Cell Processes

AbstractColor information is encoded by two parallel pathways in the mammalian retina. One pathway compares signals from long- and middle-wavelength sensitive cones and generates red-green opponency. The other compares signals from short- and middle-/long-wavelength sensitive cones and generates blue-green (yellow) opponency. Whereas both pathways operate in trichromatic primates (including humans), the fundamental, phylogenetically ancient color mechanism shared among most mammals is blue-green opponency. In this review, we summarize the current understanding of how signals from short-wavelength sensitive cones are processed in the primate and nonprimate mammalian retina, with a focus on the inner plexiform layer where bipolar, amacrine, and ganglion cell processes interact to facilitate the generation of blue-green opponency.

Misinterpreting Changes of Illuminant on Complex Mondrian Patterns

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 111-111
Author(s):  
S M C Nascimento ◽  
D H Foster
Keyword(s):  
Visual System ◽  
Temperature Change ◽  
Short Wavelength ◽  
Choice Experiment ◽  
The Other ◽  
Invariant Cone ◽  
Colour Temperature ◽  
Long Wavelength ◽  
Naturally Occurring ◽  
Colour Changes

Ratios of cone excitations from different surfaces of the same coloured scene are almost invariant under illuminance changes, and might provide the cue by which the visual system discriminates illuminant from non-illuminant changes in coloured scenes. Previous work with pairs of surfaces showed that observers were able to detect small, naturally occurring, violations in these ratios (Nascimento and Foster, 1995 Perception24 Supplement, 60 – 61). In the present study, sensitivity to violations was assessed with more complex, Mondrian patterns. In a two-interval forced-choice experiment, two colour transformations of the same Mondrian pattern were compared by observers. The patterns comprised 7 × 7 coloured patches. Each patch was a simulation of a Munsell surface, and the whole pattern was illuminated by a Planckian illuminant of variable colour temperature. In one of the intervals only the colour temperature of the illuminant changed; in the other, the same colour-temperature change was made, but, in addition, the spectral reflectances of the surfaces were adjusted such that all cone ratios were exactly preserved for the three classes of cone. The task was to identify which of the intervals contained the pure illuminant change. Observers could reliably discriminate the intervals but systematically interpreted colour changes with invariant cone-ratios as being illuminant changes, with a probability that increased as the degree of violation of invariance increased. Performance depended mainly on long-wavelength-sensitive cones, less on medium-wavelength-sensitive cones, and little or not at all on short-wavelength-sensitive cones or luminance signals. Cone-excitation ratios, although sometimes unreliable, appear to be the dominant cue for deciding on the nature of colour changes.

The absorption of light by calcium vapour (2100 to 1080 Å)

1960 ◽  
Vol 256 (1284) ◽  
pp. 53-61 ◽  
Keyword(s):  
Short Wavelength ◽  
Absorption Lines ◽  
Continuous Absorption ◽  
Absorption Of Light ◽  
Line Absorption ◽  
Short Wavelength Side ◽  
No Absorption ◽  
Wavelength Side

Continuous absorption and line absorption of radiation in calcium vapour has been measured from the 4 s 4 s 1 S 0 → 4 snp 1 P 1 series limit at 2028 to 1080 Å. Two perturbed series of auto-ionization lines (4 s 4 s 1 S 0 → 3 dnp 1 P 1 and → 3 dnp 3 P 1 ) are recorded and analyzed. A second series limit is observed at 1589 Å. This is probably two unresolved limits corresponding to the two series of auto-ionization lines. No absorption lines are observed on the short wavelength side of 1589 Å. The f -values of the lines vary from 2.4 x 10 -2 to 6 x 10 -5 and the half-lives (calculated from measurements of the half-widths of the lines) vary from 30 to 260 x 10- 15 s. The f -value for the 4 s 4 s 1 S 0 → 4 snp 1 P 1 continuum is estimated to be 0.012 (including an allowance for a portion below 1589 Å) and the f -value for the continua from wavelength 1589 to 1080 Å corresponding to the two series of auto-ionization lines is estimated to be 0.003. The measured value of the absorption near 2028 Å is about one-fiftieth of the theoretical value which has been used in astrophysical calculations.

Spectroscopic Properties of TeO2-Bi2O3-ZnO-PbO Based Tellurite Glasses

2017 ◽  
Vol 904 ◽  
pp. 98-101 ◽  
Author(s):  
Ahmad Marzuki ◽  
Wahyudi ◽  
Adi Pramuda
Keyword(s):  
Spectroscopic Properties ◽  
Infrared Region ◽  
Tellurite Glasses ◽  
Melt Quenching ◽  
Minimum Loss ◽  
Scattering Loss ◽  
Long Wavelength ◽  
Short Wavelength Side ◽  
Quenching Method ◽  
Wavelength Side

Tellurite glasses with molar compositions of 55TeO2–2Bi2O3–[43-x] ZnO–xPbO (in mol%) with x= 1, 2, 3, 4, 5 was fabricated by melt quenching method. Their absorption spectra ranging from ultraviolet to infrared region were measured using UV-VIS-NIR spectrophotometer and FTIR. Minimum losses of all glasses were then estimated from the intersection of the ‘V’ curve formed from the intersection of the extrapolation of the IR edge on the long wavelength side of the spectrum and the scattering loss curve on the short wavelength side of the spectrum. From this work, it was that the estimated minimum loss of the investigated glasses were within the range between 2.31·10-3dB/m and 2.94·10-3 dB/m at wavelength around 5.5 μm.

Pragmatic Tyre Model for Short Wavelength Side Slip Variations

1999 ◽  
Vol 31 (2) ◽  
pp. 65-94 ◽  
Author(s):  
J.P. Maurice ◽  
M. Berzeri ◽  
H.B. Pacejka
Keyword(s):  
Short Wavelength ◽  
Tyre Model ◽  
Short Wavelength Side ◽  
Wavelength Side

Ultrastructure and Staining of Developing Elastic Tissue

1971 ◽  
Vol 29 ◽  
pp. 244-245
Author(s):  
E. N. Albert
Keyword(s):  
Fine Structure ◽  
Phosphotungstic Acid ◽  
Staining Method ◽  
Rat Aorta ◽  
Uranyl Acetate ◽  
The Other ◽  
Elastic Fibers ◽  
Elastic Tissue ◽  
Lead Citrate ◽  
New Born

Silver tetraphenylporphine sulfonate (Ag-TPPS) was synthesized in this laboratory and used as an electron dense stain for elastic tissue (Fig 1). The procedures for the synthesis of tetraphenylporphine sulfonate and the staining method for mature elastic tissue have been described previously.The fine structure of developing elastic tissue was observed in fetal and new born rat aorta using tetraphenylporphine sulfonate, phosphotungstic acid, uranyl acetate and lead citrate. The newly forming elastica consisted of two morphologically distinct components. These were a central amorphous and a peripheral fibrous. The ratio of the central amorphous and the peripheral fibrillar portion changed in favor of the former with increasing age.It was also observed that the staining properties of the two components were entirely different. The peripheral fibrous component stained with uranyl acetate and/or lead citrate while the central amorphous portion demonstrated no affinity for these stains. On the other hand, the central amorphous portion of developing elastic fibers stained vigorously with silver tetraphenylporphine sulfonate, while the fibrillar part did not (compare figs 2, 3, 4). Based upon the above observations it is proposed that developing elastica consists of two components that are morphologically and chemically different.

Further Studies on the Ultrastructure of Harderian Gland in Adult Rats

1974 ◽  
Vol 32 ◽  
pp. 288-289
Author(s):  
Alfredo Feria-Velasco ◽  
Guadalupe Tapia-Arizmendi
Keyword(s):  
Fine Structure ◽  
Domestic Fowl ◽  
Animal Species ◽  
Acinar Cells ◽  
Harderian Gland ◽  
Myoepithelial Cells ◽  
The Other ◽  
Albino Rats ◽  
Adult Rats ◽  
Cell Components

The fine structure of the Harderian gland has been described in some animal species (hamster, rabbit, mouse, domestic fowl and albino rats). There are only two reports in the literature dealing on the ultrastructure of rat Harderian gland in adult animals. In one of them the author describes the myoepithelial cells in methacrylate-embbeded tissue, and the other deals with the maturation of the acinar cells and the formation of the secretory droplets. The aim of the present work is to analize the relationships among the acinar cell components and to describe the two types of cells located at the perifery of the acini.

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