Unmasking the Illicit Trafficking of Nuclear and Other Radioactive Materials
Michael Pöschl, Leo M. L. Nollet in Radionuclide Concentrations in Food and the Environment, 2006
Transmission electron microscopy (TEM) is capable of higher magnification than SEM and typically has a spatial resolution on the order of 0.1 nm, which allows extremely small structural features to be examined [40,41]. The use of a thin sample cross section enables electrons to be passed through the sample. The resultant images enable the user to observe structural features of the material, such as particle size, porosity, crystal morphology, and the presence of individual grains, stacking faults, twin boundaries, and dislocations. Electron diffraction enables crystal structures to be determined from individual areas of a sample. Information obtained from both imaging and electron diffraction can be used to determine the processing history of materials. This information is highly valuable in providing clues for tracing the source of the material. Excellent examples highlighting the use of the technique to analyze plutonium-bearing samples are detailed in recent review articles [23,42].
Drug Substance and Excipient Characterization
Dilip M. Parikh in Handbook of Pharmaceutical Granulation Technology, 2021
X-ray diffractometry may be carried out using a powder x-ray or a single crystal diffractometer. The latter is used to elucidate the crystal structure while the powder x-ray diffractometer is for general purpose. The polymorphs of material have different crystal packing arrangements and thus produce different x-ray diffractograms with characteristic peaks that are related to lattice distances (Figure 3.8a). The extent of conversion of a crystalline drug to the amorphous form during processing can be determined by comparing the magnitude of their characteristic peaks [47]. The sharp peaks (Figure 3.8a) indicate a crystalline component, whereas broad diffraction peak or features (also referred to as “halo”) indicate an amorphous component (Figure 3.8b). The powder x-ray diffractometry method is non-destructive and requires a very small sample of the material, which can be examined without further processing. For structural determination, good single crystals are used in a single crystal diffractometer. Synchrotron sources have been employed to obtain high-resolution electron diffraction patterns for very small crystals or crystals of complex compounds. Very sensitive charge-coupled detectors have enabled electron diffraction patterns to be recorded in a few seconds using very low electron currents. In addition, microdiffractometers with 2D area detectors have been developed for quick data acquisition [48].
Inorganic Particulates in Human Lung: Relationship to the Inflammatory Response
William S. Lynn in Inflammatory Cells and Lung Disease, 2019
For many inorganic particulates, elemental composition is not sufficient for complete, accurate mineralogical characterization. In these instances, information about the crystalline structure of the material is required. Two techniques have been used in the study of inorganic particulates to obtain crystallographic data: X-ray diffraction, which is a bulk technique, and selected area electron diffraction, a microanalytical technique which permits analysis of individual microscopic particles and which may be performed on most modern transmission electron microscopes.12, 14 The diffraction of X-rays or electrons as they pass through the sample produces a characteristic pattern which may be recorded on photographic film, and the geometric and dimensional information obtained can then be related to the crystal structure through Bragg’s law. The diffraction patterns for thousands of known standard materials have been catalogued in the A.S.T.M. (American Society for Testing Materials) index. X-ray diffraction and selected area electron diffraction have been used fairly extensively in the study of inorganic particulates extracted from lung tissues.6, 24–30 In addition, X-ray diffraction may be used in the quantitative determination of mineral species (e.g., quartz31 and asbestos32).
Natural mineral fibers: conducting inhalation toxicology studies – part A: Libby Amphibole aerosol generation and characterization method development
Published in Inhalation Toxicology, 2023
Anbo Wang, Amit Gupta, Michael D. Grimm, David T. Pressburger, Barney R. Sparrow, Jamie S. Richey, John R. Shaw, Karen E. Elsass, Georgia K. Roberts, Pei-Li Yao, Matthew D. Stout, Benjamin J. Ellis, Robyn L. Ray
Selected area electron diffraction patterns presented by amphibole fibers are uniform rows of closely spaced spots with patterns that are influenced by the orientation of the fiber to the direction of the electron beam (Millette 1987). The presence of concise spots conveys the crystallinity of the fiber. Upon measurement, sets of zone-axis patterns of spots are used to describe types of amphiboles in conjunction with chemical composition measured by EDS (Meeker et al. 2003). The electron diffraction patterns for the aerosol sample and the bulk LA 2007 test material indicated the aerosol and bulk material were highly crystalline and were consistent with the standards of amphibole asbestos from the Libby amphibole, MT region (Meeker et al. 2003). Representative SAED images for aerosol sample and bulk LA 2007 test material are shown in Figure 9.
Biosynthesized gold and silver nanoparticles by aqueous fruit extract of Chaenomeles sinensis and screening of their biomedical activities
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Keun Hyun Oh, Veronika Soshnikova, Josua Markus, Yeon Ju Kim, Sang Chul Lee, Priyanka Singh, Verónica Castro-Aceituno, Sungeun Ahn, Dong Hyun Kim, Yeon Jae Shim, Yu Jin Kim, Deok Chun Yang
The crystallinity of the biosynthesized nanoparticles was evaluated by SAED and XRD techniques. The multiple electron diffraction patterns correspond to the polycrystalline nature of the nanoparticles (Figure 2(a,d)) which conform to lattice planes of Bragg’s reflection (111), (200), (220) and (311) planes. Similarly, XRD spectra of Cs-AuNps (Figure 2(b)) and Cs-AgNps (Figure 2(e)) demonstrated identical diffraction peaks. Multiple negligible diffraction peaks in Figure 2(e) were present indicating the formation of bio-organic impurities in Cs-AgNps [5]. No artificial diffraction peaks due to crystallographic impurities were evident in Cs-AuNps, indicating pure gold metal. Cs-AuNps and Cs-AgNps were face-centred cubic and primarily composed of (111) orientation [12]. From this finding, the average crystallite sizes of nanoparticles have been estimated by Scherrer equation: Cs-AuNps and Cs-AgNps maintained average crystallite sizes of 9.87 and 9.03 nm, respectively. Moreover, the crystal structures of Cs-AuNps and Cs-AgNps have lattice constants of 4.07 Å and 4.08 Å, respectively, calculated experimentally from the most intense peaks (111) of XRD diffraction patterns. The FWHM (full width at half maximum) and particle diameter sizes which correspond to the polycrystalline diffraction peaks of Cs-AuNps and Cs-AgNps were tabulated in Supplementary Tables 1 and 2.
Multifunctional magnetite nanoparticles to enable delivery of siRNA for the potential treatment of Alzheimer’s
Published in Drug Delivery, 2020
Natalia Lopez-Barbosa, Juan G. Garcia, Javier Cifuentes, Lina M. Castro, Felipe Vargas, Carlos Ostos, Gloria P. Cardona-Gomez, Alher Mauricio Hernandez, Juan C. Cruz
X-ray diffraction (XRD) was carried out in a PANalytical Empyrean diffractometer using CuKαradiation (λ = 1.5406 Å) and was used to characterize the synthesis and silanization of magnetite nanoparticles via coprecipitation and thermal decomposition. Raman spectroscopy of coprecipitated magnetite nanoparticles was recorded to observe whether the maghemite phase was formed in a high-resolution Labram HR spectrometer (Horiba, Piscataway, NJ). Scanning electron microscopy (SEM) (JSM-6490LV JEOL) and transmission electron microscopy (TEM) (FEI Tecnai G2 F20 Super Twin TMP) were used to observe nanoparticle size and morphology after silanization. TEM images were recorded after the suspension of the nanoparticles in ethanol. Electron diffraction patterns and inverse Fourier transform were applied with the software Gatan Digital Micrograph® to analyze the crystalline planes of the nanoparticles. The hydrodynamic diameter of silanized nanoparticles was calculated by Dynamic Light Scattering (DLS) technique (Nano ZS Zetasizer, Malvern Instruments, UK) and Small-angle X-ray Scattering (SAXS). Fourier Transform Infrared (FT-IR) spectra were recorded prior and after the silanization process between 3600 and 450 cm−1 and with a resolution of 4 cm−1.
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