Elemental characterization of coal,fly ash,and bottom ash using an energy dispersive X-ray fluorescence technique

A total of 18 elements viz. Si, Al, Fe, Ca, Mg, K, Na, Sr, V, Zn, Mn, Cr, Cu, Pb, Ni, Co, As and Cd were analyzed in coal, fly ash and bottom ash samples collected across India using an EDXRF technique. Various indices such as element enrichment ratio, enrichment factor (with respect to crustal average) and mineral composition were calculated. Around 95% of mass was reconstructed using the concentration of elements in this study for fly and bottom ash.     

Using medical accelerators and photon activation to determine Sr/Ca concentration ratios in teeth

This paper describes a photon activation method, studied by using two medical accelerators (energies: 15 and 18 MeV) as photon sources, for determining Sr and Ca levels and Sr/Ca ratios in tooth samples. The radionuclides formed by various photonuclear reactions were measured and identified using a gamma-spectrometry with HPGe detection system. The yields of the corresponding photonuclear reactions and the detection sensitivities for the alkaline earth metals (e.g., Ca, Sr) were surveyed and estimated in relation to the radiation dose. The minimum detectable amount of Sr was estimated to be less than 1 μg g⁻¹, allowing the Sr/Ca ratios in teeth to be determined conveniently. The Sr/Ca ratios in deciduous and permanent tooth samples obtained from local dental clinics were 0.390 and 0.565 mg g⁻¹, respectively. This photon activation method of determining Sr/Ca ratio in bones and teeth using medical accelerators for cancer treatment is thought to be useful also in biological and archaeological studies.     

Zinc, lead and copper in human teeth measured by induced coupled argon plasma atomic emission spectroscopy (ICP-AES).

Inductively Coupled Argon Plasma Atomic Emission Spectroscopy (ICP-AES) has been used to determine Pb, Zn and Cu levels in 47 exfoliated human teeth (all of which required extraction for orthodontic reasons). Lead concentrations for the group were 1.7 microg (g tooth mass)(-1) to 40.5 microg (g tooth mass)(-1). with a median of 9.8 microg (g tooth mass)(-1). A median lead level in excess of the group value was found for the teeth of six lorry drivers who were included in the study. A more significant enhancement was found for the seven subjects whose age was in excess of 60 years. The median values for Zn and Cu were 123.0 and 0.6 microg (g tooth mass)(-1) respectively. Present values for tooth-Zn are lower than published data for other ethnic groups.     

Determination of multi-element profiles of street dust using energy dispersive X-ray fluorescence (EDXRF).

Street dust samples have been collected in different areas in Hong Kong associated with various levels of traffic and pedestrian flow, and the concentrations of 23 chemical elements have been determined using energy dispersive X-ray fluorescence (EDXRF). The 23 studied elements were Na, Al, Si, Cl, Ti, Ba, V, Cr, Mn, Fe, Co, K, Ca, Ni, Cu, Zn, As, Pb, Rb, Sr, Y, Zr and Sn. A profile for average street dust for Hong Kong has been determined by taking average values for different areas. The values for the Hong Kong street dust are commensurate with the values derived in previous investigations or for other countries, except that Hong Kong street dust has much higher Cl, Ca and As concentrations. A factor analysis gives four sources for the street dust in Hong Kong: namely, mixture of metallic dust and crustal material, vehicles, road pavement materials, and mixture of marine aerosols and crustal material.     

EPR dose reconstruction for bone-seeking 90Sr.

The results of the EPR dose reconstruction in calcified tissues of dog injected with 90Sr are presented. It has been established that there is no essential difference in the values of doses absorbed in tooth tissues of teeth in symmetric positions in the mouth, whereas a significant difference occurs in the values of absorbed doses in teeth in non-symmetric positions. In the case of 90Sr internal exposure the dose reconstruction in crown dentine plays an important role. It has been found that its quantity is close to the dose in diaphyseal cortical bone of the femur, dose at the endosteal bone surface and in femural fatty marrow. The fact that these values exceed doses absorbed in tooth enamel points out the predominant contribution of internal exposure. The highest absorbed doses have been observed in metaphyseal trabecular femur bones, tooth alveolar bone walls, and cortical and trabecular vertebra that can be considered as suitable candidates for biomarkers of internal 90Sr exposure for post-mortal autopsy. The satisfactory correlation has been found between the doses reconstructed in calcified dog tissues and the doses measured by EPR in alanine dosimeters fixed in (or nearby) the sites of autopsy of bones/teeth. The experiments provide support for the view that EPR retrospective dosimetry with calcified tissues for internal exposure is unique in providing useful information on the doses obtained.     

Dependencies of the radiation sensitivity of human tooth enamel in EPR dosimetry.

The EPR dose response of tooth enamel was determined for human molars collected in Egypt. The influence of age, gender and residence of the tooth donors as well as tooth position and sample preparation on EPR sensitivity and its variability over the enamel samples was investigated. The EPR sensitivity and its variability were found to depend only on the sample preparation procedure. The variability in EPR sensitivity of enamel from Egyptian teeth was maximally 10% and the mean sensitivity was in good agreement with that of German teeth.     

Elemental analysis of coal and coal ASH by PIXE technique

Coal and coal ash samples were characterized by particle induced X-ray emission spectroscopic technique. Sixteen elements, namely K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Rb, Sr, Y and Pb were quantified in this study. Elements like K, Ca, Ti and Fe were present as major elements, whereas, other elements like V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr and Pb were present in trace level. The enrichment ratio of different ash samples with respect to coal were also estimated and discussed.     

用牙釉电子自旋共振方法估算慢性辐射损伤人员的受照剂量

目的 用于牙釉电子自旋共振对慢性辐射损伤人员的受照剂量进行估算的方法。方法 用电子自旋共振仪测定慢性辐射损伤人员牙釉电子自旋共振信号强度，用剂量－效应曲线法和附加剂量法来重建辐射损伤人员的受照剂量，探讨牙釉电子自旋共振法估算受照剂量的可行性；并比较了不同能量的射线（1.25MeV的γ射线和6MeV的X射线）对牙釉电子自旋共振信号强度的影响。结果 用两种方法估算的辐射损伤人员受照剂量基本一致；对能量1.25MeV的γ射线和6MeV的X射线进行比较，无论从剂量－效应曲线的直线系数，还是用混合照射后的剂量估算，两者差别不大。结论 慢性辐射损伤人员的受照剂量可以用于牙釉电子自旋共振方法进行估算，射线能量在1.25MeV-6MeV范围内对牙釉电子自旋共振信号强度影响不大。     

Racemization in enamel among different types of teeth from the same individual

We measured the quantity of D-aspartic acid (degree of racemization of aspartic acid) in the enamel of different types of teeth from the same individual. We studied the correlation between the degree of racemization and the time of formation of each particular tooth, as well as the applicability of the degree of racemization to estimation of chronological age. If the environmental condition of the teeth is the same, the degree of racemization is expected to be highest in teeth that completed formation in the earliest period of time. Different degrees of racemization in enamel were found among different types of teeth, even in the same individual. The degree of racemization in enamel was found to be higher in molars than in incisors, and showed a tendency that did not necessarily coincide with the time of formation. This seemed to be due to the fact that the environmental temperature was higher in the molar region located deeper in the oral cavity than the front region, and that enamel was more affected by breathing air than dentin because the D/L ratios in enamel were lower than those in dentin. Using enamel, a better estimation of chronological age was obtained from calculations based on the degree of racemization of each type of tooth than from all the different teeth together. However, these estimated ages were not better than those from dentin.     

Non-destructive and Quantitative Investigation of Jingdezhen Blue and White Porcelains Using EDXRF

The fabrication of the calibration source is a critical part for the non-destructive and quantitative investigation of blue and white porcelains using EDXRF. In order to minimize the effects on the results due to the matrix difference between the samples and the calibration source, broken porcelain pieces of the Ming and Qing dynasties with matrix conditions similar to those of the measured samples are used directly as calibration sources. The 13 trace elements, viz. Ti, Mn, Fe, Co, Ni, Cu, Zn, Ga, Pb, Rb, Sr, Y, and Zr, have been quantitatively measured for 20 imperial blue and white porcelains of the Qing dynasty and for 11 contemporary Jingdezhen porcelains. The data are then analyzed by the principal component analysis method. The clustering of the data and the identification of the porcelains are then investigated.     

山羊牙釉质电子自旋共振的剂量学特性

目的 探讨山羊牙釉质电子自旋共振(ESR)的剂量学的特性.方法 采用机械和化学处理相结合的方法,制备5组不同年龄的山羊牙釉质样品.用137 Cs γ射线照射山羊牙釉质样品,使用ESR波谱仪测量辐射前和不同辐射剂量后不同牙釉质样品的ESR信号.结果 137Cs γ射线照射前,山羊牙釉质所固有的ESR本底信号平均值为21.5,明显低于人的平均本底强度水平39.5;与人牙釉质相同,山羊牙釉质照射后产生的剂量学信号的强度与照射剂量线性相关,5组100 mg山羊牙釉质样品,其剂量学峰的辐射灵敏度的平均值为(34.3±1.9)/Gy,与人牙釉质样品的辐射响应平均值36.3/Gy非常接近.结论 人类牙釉质样品缺乏时,可以用相同辐射环境中的山羊牙釉质作为替代品进行剂量重建,为正确地评价辐射事故剂量提供科学依据.

Abstract：

Objectlve To study the properties of goat tooth enamel electron spin resonance (ESR)dosimetry.Methods Tootll enamel samples of goats were achieved by combined mechanical and chemical treatment at the ages of l,2,3,5,and 6 years.respectively and 9 enamel samples of adult molar were obtained.These enamel samples were exposed to 137Cs γ-rays at the cumulative doses of 0,0.5,1.0,2.0,and 5.0 Gy,respectively.ESR spectra Was measured before and after exposure.Results The background signal of goat tooth samples W88 21.5,significantly lower than that of the adult molar samples(39.5).The dusimetric signal intensity of the goat enamel increased with the radiation dose in a linear manner just as that of the human molars.The average radiation sensitivity of the goat tooth samples was(34.3±1.9)/Gy,close to that of the human tooth samples.Conclusions Goat teeth can be used for retrospective radiation dose reconstruction when human teeth are unavailable,in order to previde scientific data for dose reconstruction accurately.     

不同制备方法对牙釉质样品ESR信号的影响

目的研究不同制备方法对牙釉质样品ESR信号的影响，有效地提高牙釉质样品ESR剂量学的灵敏度。方法对无放射线照射史成年人臼齿分别用化学、机械以及机械加化学方法进行处理，制备牙釉质样品。利用电子自旋共振仪测定不同制备方法处理的样品在^60Coγ射线照射不同剂量后的ESR信号。比较分析其灵敏度，从而寻求一种对牙釉质样品ESR信号影响较小的样品制备及处理方法。结果不同方法处理的牙釉质样品的ESR信号，对^60Coγ射线的响应有较明显的差异。结论利用牙釉质ESR剂量学重建受照人员剂量时，尤其是使用附加照射法进行较低剂量重建时，选择合适的样品制备方法是十分重要的。     

Biophysical dose measurement using electron paramagnetic resonance in rodent teeth.

Electron paramagnetic resonance (EPR) dosimetry of human tooth enamel has been widely used in measuring radiation doses in various scenarios. However, there are situations that do not involve a human victim (e.g. tests for suspected environmental overexposures, measurements of doses to experimental animals in radiation biology research, or chronology of archaeological deposits). For such cases we have developed an EPR dosimetry technique making use of enamel of teeth extracted from mice. Tooth enamel from both previously irradiated and unirradiated mice was extracted and cleaned by processing in supersaturated KOH aqueous solution. Teeth from mice with no previous irradiation history exhibited a linear EPR response to the dose in the range from 0.8 to 5.5 Gy. The EPR dose reconstruction for a preliminarily irradiated batch resulted in the radiation dose of (1.4+/-0.2) Gy, which was in a good agreement with the estimated exposure of the teeth. The sensitivity of the EPR response of mouse enamel to gamma radiation was found to be half of that of human tooth enamel. The dosimetric EPR signal of mouse enamel is stable up at least to 42 days after exposure to radiation. Dose reconstruction was only possible with the enamel extracted from molars and premolars and could not be performed with incisors. Electron micrographs showed structural variations in the incisor enamel, possibly explaining the large interfering signal in the non-molar teeth.     

Metabolism in tooth enamel and reliability of retrospective dosimetry.

Most of the radiation centers in tooth enamel and bones are formed by the reactions COOH + gamma-->CO2- + H+, and CO2 + e- -->CO2-. These centers can be easily changed by metabolism and have a low stability in living organisms. The efficiency of CO2- radical production by irradiation is substantially different for teeth and bones in living rat, dead rat, and teeth and bone removed from rat. It is shown that the suitability of tooth enamel for retrospective dosimetry can be evaluated from the anisotropy of its EPR signals.     

Inkrementelle Strukturen im Schmelz der Milchzähne

The neonatal line (NNL) is a distinct incremental marking in the dental enamel, especially in deciduous teeth. In the course of tooth development the NNL represents the position of the enamel-forming front at the time of birth in all the teeth already forming hard tissues at this time. If birth is survived for a certain period of time, deposition of new enamel can be detected outside the NNL. The material properties of teeth, the lack of remodeling, and the known chronology of incremental structures in enamel make teeth an important source of information of vital data in retrospective analyses. Counting enamel incremental markings with circadian periodicity in postnatal enamel enables the determination of the duration of the postnatal lifespan. The lack of an NNL indicates death in utero. In this respect an important contribution can be made by structural analyses of teeth to the investigation of decomposed remains of fetuses and young infants.     

Morphological features of the microdistribution of naturally occurring 10Pb/2l0Po and 226Ra in the teeth of children and juveniles

PURPOSE: To examine the microdistribution of natural alpha-radioactivity in deciduous teeth of children and the permanent teeth of juveniles extracted for orthodontic purpose from across the UK. MATERIALS AND METHODS: The microdistribution of 210Pb-supported 210Po and 226Ra in 708 deciduous and permanent teeth and 32 foetal teeth was measured on 1442 TASTRAK alpha-particle track detectors. RESULTS: Of the various findings, a number are of special interest. Around half of the 210Pb activity in the outer enamel of deciduous teeth appears to have been acquired in utero as a result of transplacental transfer. In deciduous and permanent teeth, 226Ra is concentrated mainly in the circumpulpal region, while the highest levels of 210Po are on the highly calcified outer enamel surface. Furthermore, activity concentrations recorded on this surface were In-normally distributed. CONCLUSIONS: 210Pb-supported 210Po activity on the outer enamel surface of permanent teeth constitutes an assay of cumulative environmental exposure with which to assess exposure in bone, both in utero and in childhood. Such assessment can be used to study geographical variations in the alpha-activity in teeth. More work is also required to determine the concentrations of both 210Po and 210Pb in the foetal skeleton.     

Contamination of the coastal sea sediments by heavy metals

The distribution of major and trace elements in the coastal sea sediments along the Eastern Adriatic coast was evaluated. The concentrations of K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Br, Rb, Sr, Y, and Pb in 376 samples were measured on the grain fraction <2 mm by the use of energy dispersive X-ray fluorescence. Contour maps for concentrations of toxic elements Zn, Cu, As and Pb were produced in order to show metals accumulation areas.     

South Ural nuclear workers: Comparison of individual doses from retrospective EPR dosimetry and operational personal monitoring

As a result of EPR investigations on tooth enamel from radiation workers of the Russian nuclear facility “Mayak” in South Ural, individual doses are reconstructed. The individual doses obtained range up to 3.89 Gy. It is shown that the reconstructed doses are unreasonable until very good agreement with the original personal doses as provided by the radiation protection authority. The findings first prove the applicability of EPR dosimetry on tooth enamel for a life-time including accident dose reconstruction of individuals as a basis for epidemiological studies.     

Enamel and dentin mineralization in familial hypophosphatemic rickets: a micro-CT study

Objectives:

The aim of the present study was to analyse the mineralization pattern of enamel and dentin in patients affected by X-linked hypophosphatemic rickets (XLHR) using micro-CT (µCT), and to associate enamel and dentin mineralization in primary and permanent teeth with tooth position, gender and the presence/absence of this disease.

Methods:

19 teeth were collected from 5 individuals from the same family, 1 non-affected by XLHR and 4 affected by XLHR. Gender, age, tooth position (anterior/posterior) and tooth type (deciduous/permanent) were recorded for each patient. Following collection, teeth were placed in 0.1% thymol solution until µCT scan. Projection images were reconstructed and analysed. A plot profile describing the greyscale distance relationship in µCT images was achieved through a line bisecting each tooth in a region with the presence of enamel and dentin. The enamel and dentin mineralization densities were measured and compared. Univariate ANOVA and post hoc Tukey tests were used for all comparisons.

Results:

Teeth of all affected patients presented dentin with a different mineralization pattern compared with the teeth of healthy patients with dentin defects observed next to the pulp chambers. Highly significant differences were found for gray values between anterior and posterior teeth (p < 0.05), affected and non-affected (p < 0.05), as well as when position and disease status were considered (p < 0.05).

Conclusions:

In conclusion, the mineralization patterns of dentin differed when comparing teeth from patients with and without FHR, mainly next to pulp chambers where areas with porosity and consequently lower mineral density and dentin defects were found.     

Micro-computed tomography of a 500-year-old tooth: technical note.

OBJECTIVE: To determine whether micro-computed tomography (micro-CT) could be used to reconstruct ancient dental anatomy accurately and differentiate the enamel from the dentin, as well as to verify whether micro-CT could detect tooth disorders such as attrition or caries accurately. METHODS: Micro-CT imaging was performed, using a cone-beam micro-CT specimen scanner, on a 500-year-old human tooth found in a burial jar in the Cardomom Mountains in southwestern Cambodia. RESULTS: The occlusal surface of the tooth showed marked attrition, with the dentin extending close to the enamel layer on the crown. In addition to this, micro-CT images depicted calculus on the buccal surface and a cervical root caries lesion present on the distal surface. The sclerotic zone of the carious lesion (located deep in the destroyed dentin) and the dentin were effectively differentiated through excellent resolution and superior tissue contrast of the volume data set. Axial slices from apical to coronal show the carious lesion extending vertically along the dentin-enamel junction with an intact outer enamel surface. CONCLUSION: Micro-CT is a reproducible, nondestructive and highly accurate technique that can be successfully applied to the study of ancient teeth.