Electron microscopy chrysotile

SRM 1876b is intended for use in evaluating transmission electron microscopy (TEM) techniques used to identify and count chrysotile fibers. This SRM consists of sections of mixed-cellulose-ester filters containing chrysotile fibers deposited by an aerosol generator. 

Marconi, A., E. Menichini, and L. Paoletti (1984). A comparison of light microscopy and transmission electron microscopy results in the evaluation of the occupational exposure to airborne chrysotile fibers. Arm. Occup. Hyg. 26 321. 

Yada, K. 1971 Study of microstructure of chrysotile asbestos by high resolution electron microscopy. Acta crystallogr. A 27, 659-664. 

An excellent material for checking the validity of the corrected Kelvin equation is chrysotile, Mg3(0H)4.Si20s, which consists of hollow needles, the pore volume distribution of which can be measured both by means of calibrated electron microscopy and nitrogen capillary condensation [18]. It appears that capillary... 

Verma DK, Clark NE. 1995. Relationships between phase contrast microscopy and transmission electron microscopy results of samples from occupational exposure to airborne chrysotile asbestos. Am Ind Hyg Assoc J 56 866-873. 

Results of a survey of asbestos fibers in consumer cosmetic talc powders from Italian and international markets using electron microscopy, electron diffraction, and energy dispersive x-ray analysis showed that asbestos was detected in 6 of 14 talc samples from the European Pharmacopeia (Paoletti et al. 1984). Chrysotile was identified in 3 samples, 2 samples contained tremolite asbestos and anthophyllite asbestos, and 1 sample contained chrysotile and tremolite asbestos. The authors noted that, in all talc powders analyzed, fibrous talc particles frequently were present that were morphologically similar to amphibole asbestos fibers. Counting fibers as particles with aspect ratio >3 1 and width < 3 m, the percentages of particles that were asbestos fibers ranged from <0.03% to 0.13% for 4 samples, and were 18% to 22% for the other 2 samples. Paoletti et al. (1984) noted that the European Pharmacopeia, at that time, had not established analytical quality control of asbestos contamination. 

MCP-1 (53). Electron microscopy studies of human pleural mesothelial cells demonstrated that the cells avidly engulfed asbestos fibers including those of amosite, chrysotile, and crocidolite asbestos (54). When pleural mesothelial cells were exposed to asbestos in the presence of interleukin-la or TNF-a, there was enhancement of IL-8 release. Preincubation of the mesothelial cells with E.-l receptor antagonist protein significantly decreased release of IL-8 after stimulation with amosite or crocidolite asbestos. Asbestos is also associated with a large influx of mononuclear cells into the pleural space. Koenig et al. (53) demonstrated the presence of MCP-1 in supernatants of mesothelial cells that were activated by crocidolite asbestos. 

Optical microscopy (OM), polarized light microscopy (PLM), phase contrast microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) are the methods normally used for identification and quantification of the trace amounts of asbestos fibers that are encountered in the environment and lung tissue. Energy-dispersive X-ray spectrometry (EDXS) is used in both SEM and TEM for chemical analysis of individual particles, while selected-area electron diffraction (SAED) pattern analysis in TEM can provide details of the cell unit of individual particles of mass down to 10 g. It helps to differentiate between antigorite and chrysotile. Secondary ion mass spectrometry, laser microprobe mass spectrometry (EMMS), electron probe X-ray microanalysis (EPXMA), and X-ray photoelectron spectroscopy (XPS) are also analytical techniques used for asbestos chemical characterization. 

As is clear from the foregoing sections, there is a wide array of different observations and measurements available for every single fiber. Electron microscopy can be used to detect very thin fibers and allows us to identify different types of fibers. Therefore, nonasbestos fibers can be eliminated from the measurement. The disadvantage of the STEM method lies in the time and cost consideration. OM has more drawbacks, for example, a limited resolution. To be identified as chrysotile, fibers must exhibit their characteristic morphology and also contain magnesium and silicon, whereas anthophyllites have additional peaks of calcium or iron in their X-ray spectra. In several samples the identity of chrysotile and amphibole fibers is confirmed qualitatively using TEM (at 80 kV, magnification 20000 x ) and SAED. 

Asbestos (anthophyllite, tremolite-actinolite, amosite, crocidolite, chrysotile), nonasbestos fibres Analytical electron microscopy of 50 lung tissue samples from Matsubase, where pleural plaques are endemic Number of asbestos bodies and fibres/ 5 g wet lung tissue frequency of pleural plaques size parameter of fibres Dy mineral type Anthophyllite (mean length 25.1 n, mean diameter 0.84 (un) might be responsible for the increased prevalence of pleural plaques in Matsubase. The aspect ratio of anthophyllite (mean = 38.7) was lower than that of amosite (mean = 81.8), which, as reported hy Murai and Kitagawa (1992), was found predominantly in cases of pleural mesothelioma. Murai et al. (1997) Differences in fibre size may be related to the strength of the carcinogenicity to the pleura. 

The single analytical instrument that is appropriate for analysis of waterborne asbestos, then, is transmission electron microscopy (TEM). This high-resolution instrument clearly displays the narrowest asbestos fibers on its bright phosphor screen at magnifications of 10,000 X to 20,000 X. When the intermediate lens is focused on the back focal plane of the image, electron-diffraction (ED) patterns can be produced. Amphibole or chrysotile crystalline structures can be positively identified by measuring these patterns. Finally, specific species of amphiboles can be differentiated by EDX detectors inserted near the specimen holder [18]. 

Chrysotile NTs were synthesized and characterized by Piperno and co-workers (2007) using atomic force microscopy and transmission electron Microscopy (TEM). The results have shown that chrysotile NTs exhibit elastic behavior at small deformation. The chrysotile Young s modulus evaluated by (Piperno et al, 2007) are 159 + 125 GPa. The stoichiometric chrysotile fibers demonstrate a hollow structure with quite uniform outer diameter around 35 nm and inner diameter about 7-8 nm. The NTs are open ended with several hundred nanometers in length. 

Pipemo, S., Kaplan-Ashiri, 1, Cohen, S.R., Popovitz-Biro, R., Wagner, H.D., Tenne, R., Foresti, E., Lesci, I.G. Roveri, N. (2007) Characterization of geoinspared and synthetic chrysotile nanotubes by atomic force microscopy and transmission electron microscopy. Advanced Functional Materials, 17, 3332-3338. 

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