Tooth enamel mineralization in ungulates: implications for recovering a primary isotopic time-series

In vitro and in vivo methods of Raman spectroscopy have been developed to assess the degree of mineralization of the enamel of different functional groups. This article presents comparative studies that were carried out using scanning Raman microspectroscopy with various sources of laser excitation with wavelengths of 532, 785, and 1064 nm. It is shown that the intensity of Raman scattering of enamel can be a measure of its thickness. The obtained dependence of the Raman scattering intensity on the distance from the incisal edge is in good agreement with the literature data, where two independent methods (computer tomography and electron microscopy) are used to determine the enamel thickness values. The proposed methods can be considered as potential quantitative methods for express diagnostics of the state of tooth enamel in vivo.

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Chordata

On Biomineralization ◽

10.1093/oso/9780195049770.003.0011 ◽

1989 ◽

Author(s):

Heinz A. Lowenstam ◽

Stephen Weiner

Keyword(s):

Calcium Phosphate ◽

Navigation System ◽

Tooth Enamel ◽

Carbonate Minerals ◽

Single Class ◽

Iron Minerals ◽

Phosphate Mineral ◽

Mineralized Tissues ◽

Mineralization Processes ◽

Enamel Mineralization

In the field of biomineralization the phylum Chordata is the most intensively studied, as one of its subphyla, the Craniata, includes our own species. The Craniata are often referred to as the vertebrates, a term that alludes to the importance of the endoskeleton in denning the essential character of these animals. The phylum Chordata also contains three other subphyla, only one of which has members that form mineralized hard parts. They belong to the Urochordata or tunicates. In fact, mineralization is confined to several families of a single class of urochordates, the Ascidiacea. Table 9.1 is a compilation of the known biogenic minerals formed by members of the Chordata, together with the sites at which they form and their presumed functions. The table includes no less than 17 different minerals, which should dispel any notion that mineralization in the chordates is synonymous with "calcium phosphate" deposition. It is, of course, true that the mineralized skeletal hard parts of most of the Craniata or vertebrates contain a calcium phosphate mineral, usually in the carbonated form called dahllite. However, the vertebrates also form four different carbonate minerals that are most commonly found in the vestibulary apparatus (see Chapter 10). They form three different iron minerals, which includes magnetite found in the navigation system of various vertebrate genera. The Ascidiacea also form a diverse array of minerals. Interestingly, however, their diversity is essentially confined to one class, the Pyuridae, which form no less than six different minerals, including two phosphate minerals. In this chapter we first describe biomineralization processes in the Ascidiacea followed by detailed discussions of mineralization processes in the Chordata or vertebrates. For convenience, the section on vertebrate mineralization is divided according to the major mineralized tissues: bone (dentin), cartilage, and tooth enamel. Mineralization in the vestibulary apparatus is discussed in Chapter 10.

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The LDE-Type Flare Occurrence (1969-1993)

International Astronomical Union Colloquium ◽

10.1017/s0252921100025458 ◽

1994 ◽

Vol 144 ◽

pp. 279-282

Author(s):

A. Antalová

Keyword(s):

Time Series ◽

Fourier Analysis ◽

Sunspot Cycle ◽

List Type ◽

Type Number ◽

Solar Cycles ◽

Type Iv ◽

Long Duration ◽

Cycle Maximum ◽

Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

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