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Electron Microscopy in Lung Research
Published in Joan Gil, Models of Lung Disease, 2020
Two types of electron microscope are widely available: transmission electron microscopes (TEMs) and scanning electron microscopes (SEMs). Each uses a different mechanism of image formation and gives a different kind of information (Fig. 1) (Watt, 1985). In the TEM, a thin specimen, usually less than 0.1 μm thick, is placed in the electron beam. The electrons pass through the specimen and are brought to a focus on a fluorescent screen or photographic film beneath it. Contrast results from scattering of electrons as they pass through the specimen. The unscattered electrons pass through the specimen to interact with the fluor of the screen or photographic emulsion. Scattering of electrons is a function of the atomic number of the atoms making up the specimen. The bulk of biological material is made up of elements of low atomic number (hydrogen, oxygen, carbon, and nitrogen), so most biological samples have little inherent electron contrast. Contrast is usually introduced by the OsO4 used nearly universally as a fixative, and by the use of heavy metal stains.
Structural Determination of the Polycystin-2 Channel by Electron Cryo-Microscopy
Published in Jinghua Hu, Yong Yu, Polycystic Kidney Disease, 2019
A transmission electron microscope (TEM) operating at 200 or 300 kV. To obtain better movies, the TEM typically is equipped with a field emission gun (FEG) as an electron source and a direct electron detector. Tecnai TF20 and Tecnai TF30 Polara microscopes from FEI Company and K2 Summit direct electron detector from Gatan Inc. were used to solve the 3D structure of the polycystin-2 protein.
Identifying Nanotoxicity at the Cellular Level Using Electron Microscopy
Published in Suresh C. Pillai, Yvonne Lang, Toxicity of Nanomaterials, 2019
Kerry Thompson, Alanna Stanley, Emma McDermott, Alexander Black, Peter Dockery
Conventionally it is regarded that there are two main types or modes of electron microscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). There have been many adaptations of these techniques, the base microscopes and their associated specimen preparations which include low temperature and cryo techniques. To ensure that the specimen is able to withstand the electron beam, various preparatory techniques (Figure 7.1) must be carried out and will be discussed in greater detail in Section 7.3. When gathering three-dimensional (3D) information about a specimen, the microscopist generally employs the SEM, where it is used to visualise the surface topography of a specimen. TEM images are generally two dimensional (2D) in nature but in recent years and with advances in technology, computational power, and software packages a series of 2D TEM images can be collected via electron tomography (ET) and reconstructed to create a 3D model of the structure of interest.
Progress in the development of stabilization strategies for nanocrystal preparations
Published in Drug Delivery, 2021
Jingru Li, Zengming Wang, Hui Zhang, Jing Gao, Aiping Zheng
The sizes and shapes of nanocrystals were analyzed via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In SEM, image results are generated through the interaction between the electron beam and atoms at various depths in the sample. For example, by collecting secondary electrons and backscattered electrons, information about the microstructure of the material can be obtained (Figure 7). In a transmission electron microscope, an image is obtained by capturing transmitted electrons in a sample. The accelerated and clustered electron beam can be transmitted to a very thin sample, and the electrons collide with the atoms in the sample and change direction, thereby generating solid angle scattering, which can be used to observe the ultrastructures of particles, and the resolution can reach 0.1 ∼ 0.2 nm (Figure 8).
The effect of physico-chemical treatment in reducing Listeria monocytogenes biofilms on lettuce leaf surfaces
Published in Biofouling, 2020
Md. Furkanur Rahaman Mizan, Hye Ran Cho, Md. Ashrafudoulla, Junbin Cho, Md. Iqbal Hossain, Dong-Un Lee, Sang-Do Ha
The TEM (FEI Company, Hillsboro, OR, USA) transfers electrons of specific energy through the spectrometer to form an image. The basic principle is the same as for light microscopy, but electrons are used instead of light. The wavelength of electrons is much smaller than that of light, so the optimal resolution attainable for TEM images is many orders of magnitude better than that from a light microscope. The effect of ClO2 on the integrity of L. monocytogenes cells was investigated by following a recently published article with some modification (Ashrafudoulla et al. 2020b). After treatment of a sample with ClO2, the bacterial culture was centrifuged with 8,000 g for 12 min, at 4 °C to collect pellets and washed three times with PBS. An aliquot of 5 µl of untreated or treated bacterial solutions was placed on a 400-mesh copper grid for 1 min to attach and excess solution was drained off with a filter. Negative staining was performed with 2% methylamine tungstate (Nano-W; 210 Nanoprobes, Yaphank, NY, USA). The specimens were observed at 200 kV using a 211 FEI Tecnai 20 transmission electron microscope (FEI Company, Hillsboro, OR, United States).
Evaluating the histomorphological and biochemical changes induced by Tributyltin Chloride on pituitary-testicular axis of adult albino rats and the possible ameliorative role of hesperidin
Published in Ultrastructural Pathology, 2023
Sahar F. Shaban, Maha A. Khattab, Samar H. Abd El Hameed, Shaimaa A. Abdelrahman
Detection of Ki-67 protein and FSH β chain protein were carried out using streptavidin – biotin complex immunoperoxidase system. Paraffin sections were deparaffinized and incubated in 0.1% hydrogen peroxide to block the endogenous peroxidase followed by rinsing in phosphate-buffered saline (PBS). Antigen-retrieval was carried out by microwave treatment (20 min, 0.01 Mol/L citrate buffer, pH 6). Thereafter, the sections were incubated overnight with the primary antibody. For detection of Ki-67, sections were incubated with rabbit monoclonal Ki-67 Antibody (rabbit anti ki67 monoclonal antibody of (product No. [SP6] ab16667 Abcam Chemical Company, Cambridge, USA), dilution was 1/200.For detection of FSH β chain protein, sections were incubated with rabbit anti FSHβ monoclonal antibody ([EPR24439–141] Abcam Chemical Company, Cambridge, USA), dilution was 1/100. After numerous washes with PBS, sections were incubated with biotinylated anti-rabbit immunoglobulins for amplification of the antigen-antibody reaction. Then, sections were incubated with the streptavidin – biotin peroxidase complex (CAS No. 85878, Sigma-Aldrich Chemical Company, St. Louis, MO, USA). Thereafter, the reaction was visualized with 3,30 -diaminobenzidine-tetrahydrochloride (DAB) as a chromogen. Lastly, sections were counterstained with Mayer’s hematoxylin, dehydrated and mounted. For negative control, primary antibody step was replaced with PBS. Positive brown reaction for Ki67 was nuclear while FSH β chain protein was cytoplasmic. Transmission electron microscope study (TEM)37: