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1 Introduction According to the involute profile shape there are three helical gear types: x-zero gear, normal teeth type and modified teeth type [ 1–4 ]. The geometric designing of many types of basic gear drives could be found in the [ 1

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. 12. P. Mahoney 2012 Incremental enamel development in modern human deciduous anterior teeth Am J Phys Anthropol 147

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: teeth with active caries lesions (internal half of dentin), no history of spontaneous pain, no sign suggesting irreversible pulpitis, or pulp necrosis. Clean the entire surface of the teeth from plaque and calculus using a lesion. The caries is

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Abstract  

Geometric progression fitting method has been used to compute energy absorption build-up factor of teeth [enamel outer surface, enamel middle, enamel dentin junction towards enamel, enamel dentin junction towards dentin, dentin middle and dentin inner surface] for wide energy range (0.015–15 MeV) up to the penetration depth of 40 mean free path. The dependence of energy absorption build-up factor on incident photon energy, penetration depth, electron density and effective atomic number has also been studied. The energy absorption build-up factors increases with the penetration depth and electron density of teeth. So that the degree of violation of Lambert–Beer (I = I 0eμt ) law is less for least penetration depth and electron density. The energy absorption build-up factors for different regions of teeth are not same hence the energy absorbed by the different regions of teeth is not uniform which depends on the composition of the medium. The relative dose of gamma in different regions of teeth is also estimated. Dosimetric implication of energy absorption build-up factor in teeth has also been discussed. The estimated absorption build up factors in different regions of teeth may be useful in the electron spin resonance dosimetry.

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1.1 The properties of spur gear having normal teeth The basic rack gear tooth profile contains the base parameters of the normal section (circular pitch, whole depth, basic rack gear tooth profile angle and clearance

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
M. A. Rizzutto
,
N. Added
,
M. H. Tabacniks
,
F. Falla-Sotelo
,
J. F. Curado
,
C. Francci
,
R. A. Markarian
,
A. Quinelato
,
F. Youssef
,
M. Mori
, and
M. Youssef

Summary  

A collaboration project between the School of Dentistry and the Institute of Physics of the University of São Paulo has been established to measure elemental concentrations in teeth by proton induced X-ray emission (PIXE) and heavy ion elastic recoil detection analysis (HI-ERDA) techniques. Data on trace elements in human, bovine and swine teeth, analyzed by PIXE with a 2.4 MeV proton beam, were compared and concentrations for several elements were obtained with tens of mg/g sensitivity. HI-ERDA measurements employing a 52 MeV Cl beam were done to evaluate changes in elementary concentration in dental enamel after bleaching treatment with different products in 25 bovine incisors teeth. This non-destructive technique allowed the measurements of Ca, P, O and C concentrations above the limit of 100 mg/g.

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]. The main property of the spur gear pairs having normal teeth is the application of the addendum modification that is why the tooth connection is established on the rolling circles [ 4–8 , 11 , 12 ]. Consequently, the base angle ( α

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Abstract  

A new method for non-destructive depth profiling of fluorine has been developed which extends the profiling range to much larger depths than hitherto possible. In this method the thick-target yield of 6–7 MeV gammas from the reaction of 19F(p,αγ) 16O in the tooth sample, was measured as a function of the incident energy from threshold to up to 2.7 MeV and the yield curve plotted. This curve was compared to the calculated yield curve of 6–7 MeV gammas from the same reaction but on an enamel matrix containing uniformly distributed fluorine. The difference in the shape of the two curves was only due to the non-uniform distribution of fluorine in the tooth sample, which could then be calculated. By making use of this method F-depth profiles in teeth of monkeys were determined non-destructively to a depth of 14 μm. This method is also applicable for profiling other elements through appropriate resonant or non-resonant nuclear reactions.

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JPC - Journal of Planar Chromatography - Modern TLC
Authors:
T. Katarzyna Różyło
,
Anna Żabińska
,
Ludomir Kwietniewski
,
Teresa Bachanek
, and
Anna Jamrożek-Mańko

Levels of formaldehyde, formed within the cells of plants, animals, and man, are related to the physiological state of an organism. We have previously reported the possibility of determining the formaldehyde content of human teeth in some physiological states, and it was established that the level of HCHO in carietic teeth is higher than in healthy teeth. The aim of the work described in this paper was the OPLC determination of HCHO levels in teeth suffering from eight different rare pathological disorders. It was shown that significantly different levels of formaldehyde were present in teeth in different pathological states. The highest HCHO content was observed in teeth with acute inflammatory changes. The lowest level was found in teeth with no inflammatory changes.

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Abstract  

Bone is a critical organ for the accumulation of 90Sr but also of other “bone-seeking” radionuclides such as Ra, Pb, Th, U and Pu. That's why a simple radiochemical procedure to separate 90Sr, 210Pb, 226Ra, Thnat. Unat., 238Pu and 239/240Pu from bone and teeth was developed. The separation scheme is based on extraction chromatography. Deciduous teeth, extracted from children born in 1982-1991 were collected in various regions of Germany and in Northwest Ukraine and analyzed for 90Sr concentrations with regard to the Chernobyl accident in 1986. The teeth were grouped into samples according to the year of birth and the residence of the donors. The 90Sr content in teeth from the Ukraine (mean = 63.8 mBq/g Ca) averaged more than twice as much as that found in teeth from Germany (mean = 28.4 mBq/g Ca). The obvious explanation for this effect is that the concentration of 90Sr decreased with increasing distance from the damaged Chernobyl nuclear power plant. The measured levels of 90Sr concentrations, however, were much lower than 90Sr concentrations determined in the mid-60s and mid-70s.

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