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When the calculus dimensions were so small that they do not allow powdering, the bulk sample was merely deposited on the tape. For quantification, certified standards of apatite, soil and SO2Zn were used. Special care was taken to avoid intercontamination among the samples and also standards during the sample... 顯示更多 When the
calculus dimensions were so small that they do not allow
powdering, the bulk sample was merely deposited on the
tape. For quantification, certified standards of apatite, soil
and SO2Zn were used. Special care was taken to avoid
intercontamination among the samples and also standards
during the sample preparation procedure.The X-ray fluorescence analysis was carried out at the
D09B-XRF beamline of the Laboratorio Nacional de Luz
Sı´ncrotron (LNLS, Campinas, Brazil). Storage ring and
beamline characteristics were described in a previous article.
10 The setup conditions for the measurements are shown
in Table II. The features and energies of the incident radiation
make this analytical method insensible to the presence
TABLE I
The Sites and Teeth from Which Dental Calculi Were Extracted
Site M41 D41 M31
D31
MD33
M32
D42
D32
M42
M42
D32
D42
M32
MD43
MD33
D31 M31 D41 M41
Month 1 2 3 4 5 6 7 8 9 10 11 12
A period of 1 month was left between the collection of each sample. M, mesial side; D, distal side.
TABLE II
Characteristics of the Radiation Beam, Sample, and Experimental Setup
Beam Spectrum
Critical
Energy
Photon
Fluxa
Irradiation
Area Filters Geometry Detector
White 0.57 keV 3.0921012 5 mm2 Al 0.5 mm 45–45° Si(Li)
Atmosphere
Measuring
Time (LT) Samples Sample Area Sample Holder
Sample
Weights Standards
Air
200 sec per
sample 19 4 mm2 Scoth tape
15–65
mg/cm2
Apatite, soil,
SO2Zn
aBeam flux in [photons/mrad s(0.1%E/E)] units.
624 ABRAHAM ET AL.
of organic materials and do not induce changes in crystal
structures.
The whole process of beam alignment, shaping, and positioning
is made by remote-controlled stepper motors and
monitored with local videocameras. In this way, the entire
sample area was irradiated during the measurements, keeping
the excitation of the cellophane tape as small as possible
to reduce scattering contributions.
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