Strontium Labelling for Verifying Daily Growth Increments in the Statolith of the Short-Finned Squid (Illex illecebrosus)

1985 ◽  
Vol 42 (2) ◽  
pp. 380-383 ◽  
Author(s):  
Geoffrey V. Hurley ◽  
Paul H. Odense ◽  
Ron K. O'Dor ◽  
Earl G. Dawe
Keyword(s):  
Line Profile ◽  
Electron Microprobe ◽  
Chloride Solution ◽  
Ground Surface ◽  
Strontium Chloride ◽  
Scattered Electron ◽  
Daily Growth ◽  
X Ray ◽  
Distinct Band ◽  
Growth Increments

Shrimp soaked in strontium chloride solution were fed to short-finned squid (Illex illecebrosus). The strontium was deposited in the statolith of the squid where, with the use of an electron microprobe, it was detectable as a distinct band on the ground surface of the statolith. Strontium X-ray maps and corresponding back-scattered electron images in the atomic contrast mode were obtained. Use was made of a strontium X-ray line profile to discriminate between markings deposited only 2 d apart. Micrographs were compared with light micrographs to verify the daily growth increments.

Complex sequential pyroxene growth in tholeiitic hypabyssal rocks from southern West Greenland

1986 ◽  
Vol 50 (357) ◽  
pp. 491-502 ◽  
Author(s):  
R. P. Hall ◽  
D. J. Hughes ◽  
C. R. L. Friend
Keyword(s):  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Scattered Electron ◽  
X Ray ◽  
West Greenland ◽  
Chemical Gradients ◽  
Sequential Precipitation ◽  
The Individual ◽  
Individual Grains

AbstractChemically complex pyroxenes which occur in early Proterozoic tholeiitic dolerite dykes in southern West Greenland have been investigated using back-scattered electron (BSE) imagery, X-ray mapping and electron microprobe analysis. A wide variety of compositions occur within individual pyroxene grains in these rocks. They can be explained by simultaneous nucleation of different pyroxenes, the evolution of domains around these nucleii as a response to differential chemical gradients and the sequential precipitation of different pyroxenes at progressively lower temperatures. As an example, the individual grains in one dyke sample contain domains of bronzite, hypersthene, magnesium pigeonite, augite, and subcalcic augite. Olivine in this sample varies in composition from Fo70to Fo33, although individual grains are only weakly zoned. The wide variation in pyroxene and olivine compositions suggests ranges of crystallization temperatures fromc.1250° to as low as 825°C. Such compositionally variable pyroxenes are possibly characteristic of hypabyssal tholeiitic rocks.

scholarly journals Growth and development of the third permanent molar in Paranthropus robustus from Swartkrans, South Africa

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Christopher Dean ◽  
Clément Zanolli ◽  
Adeline Le Cabec ◽  
Mirriam Tawane ◽  
Jan Garrevoet ◽  
...  
Keyword(s):  
South Africa ◽  
Growth Curves ◽  
Daily Growth ◽  
Tooth Formation ◽  
Dental Maturation ◽  
X Ray ◽  
Permanent Molar ◽  
Growth Increments ◽  
Micro Tomography ◽  
Late Maturation

Abstract Third permanent molars (M3s) are the last tooth to form but have not been used to estimate age at dental maturation in early fossil hominins because direct histological evidence for the timing of their growth has been lacking. We investigated an isolated maxillary M3 (SK 835) from the 1.5 to 1.8-million-year-old (Mya) site of Swartkrans, South Africa, attributed to Paranthropus robustus. Tissue proportions of this specimen were assessed using 3D X-ray micro-tomography. Thin ground sections were used to image daily growth increments in enamel and dentine. Transmitted light microscopy and synchrotron X-ray fluorescence imaging revealed fluctuations in Ca concentration that coincide with daily growth increments. We used regional daily secretion rates and Sr marker-lines to reconstruct tooth growth along the enamel/dentine and then cementum/dentine boundaries. Cumulative growth curves for increasing enamel thickness and tooth height and age-of-attainment estimates for fractional stages of tooth formation differed from those in modern humans. These now provide additional means for assessing late maturation in early hominins. M3 formation took ≥ 7 years in SK 835 and completion of the roots would have occurred between 11 and 14 years of age. Estimated age at dental maturation in this fossil hominin compares well with what is known for living great apes.

Long-term variations in individual particle types in the aerosol of Phoenix, Arizona, as determined using automated electron microprobe analysis and multivariate statistical techniques

1993 ◽  
Vol 51 ◽  
pp. 742-743
Author(s):  
Karen A. Katrinak ◽  
James R. Anderson ◽  
Peter R. Buseck
Keyword(s):  
Electron Microprobe ◽  
Fine Fraction ◽  
Coarse Fraction ◽  
Motor Vehicles ◽  
Multivariate Statistical Methods ◽  
Multivariate Statistical ◽  
X Ray ◽  
Mineral Particles ◽  
Anthropogenic Air Pollutants

Aerosol samples were collected in Phoenix, Arizona on eleven dates between July 1989 and April 1990. Elemental compositions were determined for approximately 1000 particles per sample using an electron microprobe with an energy-dispersive x-ray spectrometer. Fine-fraction samples (particle cut size of 1 to 2 μm) were analyzed for each date; coarse-fraction samples were also analyzed for four of the dates.The data were reduced using multivariate statistical methods. Cluster analysis was first used to define 35 particle types. 81% of all fine-fraction particles and 84% of the coarse-fraction particles were assigned to these types, which include mineral, metal-rich, sulfur-rich, and salt categories. "Zero-count" particles, consisting entirely of elements lighter than Na, constitute an additional category and dominate the fine fraction, reflecting the importance of anthropogenic air pollutants such as those emitted by motor vehicles. Si- and Ca-rich mineral particles dominate the coarse fraction and are also numerous in the fine fraction.

Microstructure of post-deformed ECAP-Ti investigated by Multiple X-Ray Line Profile Analysis

2006 ◽  
Vol 2006 (suppl_23_2006) ◽  
pp. 129-134 ◽  
Author(s):  
E. Schafler ◽  
K. Nyilas ◽  
S. Bernstorff ◽  
L. Zeipper ◽  
M. Zehetbauer ◽  
...  
Keyword(s):  
Line Profile ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
X Ray

scholarly journals Resonant Effect of High-Energy Electron–Positron Pairs Production in Collision of Ultrarelativistic Electrons with an X-ray Electromagnetic Wave

Universe ◽  
2021 ◽  
Vol 7 (7) ◽  
pp. 210
Author(s):  
Georgii K. Sizykh ◽  
Sergei P. Roshchupkin ◽  
Victor V. Dubov
Keyword(s):  
High Energy ◽  
Energy Electron ◽  
Opening Angle ◽  
High Energy Electron ◽  
Scattered Electron ◽  
Differential Probability ◽  
X Ray ◽  
Electron Positron ◽  
Pulsar Radiation ◽  
Resonant Effect

The process of resonant high-energy electron–positron pairs production by electrons in an X-ray pulsar electromagnetic field is studied theoretically. Under the resonance conditions, the second-order process under consideration effectively reduces into two sequential first-order processes: X-ray-stimulated Compton effect and X-ray–stimulated Breit–Wheeler process. The kinematics of the process is studied in detail: the dependencies of the energy of the scattered electron on its outgoing angle and the energies of the particles of the pair on the outgoing angle of the scattered electron and the opening angle of the pair are obtained. The analysis of the number of different possible particles energies values in the entire range of the angles is also carried out, according to which the energies of the particles of the pair can take up to eight different values at a fixed outgoing angle of the scattered electron and opening angle of the pair. The estimate of the resonant differential probability per unit time of the process, which reaches the maximum value of 24 orders of the value of the non-resonant differential probability per unit time, is obtained. The angular distribution of the differential probability per unit time of the process is analyzed, particularly for the case of high-energy positrons presenting in pulsar radiation.

Diffusivity, Solubility and Speciation of Sulphur in Silicate Melts

2006 ◽  
Vol 46 ◽  
pp. 93-97 ◽  
Author(s):  
J. Stelling ◽  
Harald Behrens ◽  
Joachim Deubener ◽  
Stefan Mangold ◽  
Joerg Goettlicher
Keyword(s):  
High Temperature ◽  
Electron Microprobe ◽  
Industrial Production ◽  
Silicate Melts ◽  
Viscosity Data ◽  
Decomposition Products ◽  
X Ray ◽  
Diffusion Couple Technique ◽  
X Ray Absorption ◽  
Diffusion Profiles

Diffusion and solubility of sulphur have important effects on the degassing of silicate melts. Both properties are closely related to the structural incorporation of sulphur in the melt. Depending on the oxygen fugacity, sulphur can be present as sulphide (S2-), sulphite (S4+) or sulphate (S6+). Sulphates play an important role in the industrial production of glasses especially in the fining process. The decomposition products of sulphate amass in bubbles which ascend and homogenize the melt. Structural incorporation of sulphur in glasses is studied by XANES (X-ray Absorption Near Edge Spectroscopy). Diffusion of sulphur is investigated in simple silicate systems using the diffusion couple technique. First diffusion profiles were measured in sodium trisilicate glasses by electron microprobe. The results indicate that sulphur diffusivity in high temperature melts is close to the Eyring diffusivity calculated from viscosity data.

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