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Modern Microscopic Methods of Bioaerosol Analysis
Published in Christopher S. Cox, Christopher M. Wathes, Bioaerosols Handbook, 2020
Most beam-scanning confocal microscopes are based on a standard light microscope and use epi-illumination in the same manner as a fluorescence microscope. Standard dichroic mirrors and filters select the imaging wavelengths. Thus, the confocal microscope may be used to detect fluorochromes. The wavelength of the excitation is limited by the type of laser employed. For example, the BioRad MRC1000, shown in Figure 11.2, has a krypton-argon laser that can detect three fluorescent labels in the blue, yellow and red wavelengths, allowing triple labeling experiments to be carried out. Confocal UV microscopes also are available for fluorochromes such as DAPI, using, for example, a 325 nm helium-cadmium laser.
Optical Measurements for Phase Change Heat Transfer
Published in Josua P. Meyer, Michel De Paepe, The Art of Measuring in the Thermal Sciences, 2020
Jungho Kim, Iztok Golobič, Janez Štrancar
Temperature mapping can be brought to another level with nano-sized temperature probing in the form of nanoparticles with the emission being insensitive to the local environment and with the possibility of redistribution within the entire system, including complex systems such as a living cell. While high spatial, temporal, and temperature resolutions have previously been achieved within a substrate just below the interface, the latest application suggests the same can also be achieved within the entire system under observation. Using optical sectioning of a confocal fluorescence microscope, even 3D mapping is theoretically possible with, of course, a much lower temporal resolution.
Survey of Endogenous Biological Fluorophores
Published in Mary-Ann Mycek, Brian W. Pogue, Handbook of Biomedical Fluorescence, 2003
Rebecca Richards Kortum, Rebekah Drezek, Konstantin Sokolov, Ina Pavlova, Michele Follen
Masters and Chance [9] described a method to map the redox state of tissues in three dimensions using confocal fluorescence imaging to measure the intrinsic fluorescence probes that report on cellular metabolism: NAD(P)H and the oxidized flavoproteins. The basis of this technique is that the quantum yield of NAD(P) is higher for the reduced form and lower for the oxidized form, whereas the opposite is true for the flavoproteins [9]. By measuring the ratio of fluorescence intensity of these two chromophores with a confocal fluorescence microscope, a physical map corresponding to the local redox state of the tissue can be created [9].
Assays and enumeration of bioaerosols-traditional approaches to modern practices
Published in Aerosol Science and Technology, 2020
Maria D. King, Ronald E. Lacey, Hyoungmook Pak, Andrew Fearing, Gabriela Ramos, Tatiana Baig, Brooke Smith, Alexandra Koustova
Phase-contrast microscopy is a variant of bright-field microscopy that takes advantage of the variation in the refractive index between a microorganism and its surrounding medium to enhance contrast and provide easier viewing (Zernike 1942; Morris 1995). Phase-contrast microscopy can be used to observe live microorganisms, but is particularly useful for imaging low-contrast specimens. Fluorescence is a powerful tool that can be used in microscopy to examine particular structures or molecules in a microorganism or its surroundings. Fluorescence can be achieved either with fluorescent dyes or with cells that are naturally or artificially fluorescent. A variant of fluorescent microscopy is confocal microscopy, which allows very precise resolution and location of fluorescent molecules in a cell. Epifluorescence microscopy has been used to determine viral abundance in bioaerosols (Michaud et al. 2018).
Imaging resolution and properties analysis of super resolution microscopy with parallel detection under different noise, detector and image restoration conditions
Published in Journal of Modern Optics, 2018
Zhongzhi Yu, Shaocong Liu, Shiyi Sun, Cuifang Kuang, Xu Liu
Confocal microscopy is widely employed as a method that can enhance resolution significantly. However, the trade-off between the signal-to-noise ratio (SNR) and resolution has stymied further improvement of the performance of confocal microscopy. A larger pinhole size allows more incident light on the detector; however, the resolution decreases owing to a more blurred point spread function (PSF) introduced by the larger pinhole size. Although pursuing the sharper PSF theoretically guarantees higher resolution, in this case, most of the light emitted from sample would be blocked by the pinhole, leading to a sharp decrease in SNR (1–4). To surpass this limit, using parallel detection to replace the pinhole could be an effective method to enhance the resolution and improve the SNR. Until now, various parallel detection methods have been proposed, including spinning disc microscopy (5,6), optical photon reassignment microscopy (7), rescan confocal microscopy (8), fluorescence depletion microscopy (9,10), and virtual k-space modulation optical microscopy (11). These methods have been implemented in a variety of applications.
A review on mechanical and tribological characterization of boron carbide reinforced epoxy composite
Published in Advanced Composite Materials, 2021
Sunny Bhatia, Surjit Angra, Sabah Khan
Confocal microscopy is also used to monitor the curing of the clear and filled epoxies. In this method point illumination and a pinhole are used in front of a detector in an optically conjugate plane [45]. Confocal microscopy allows generation of 3D images of the specimen.