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Experimental Methods in Cardiovascular Mechanics
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
Polarized light microscopy is a contrast-enhancing technique that can be useful for analyzing birefringent (or optically anisotropic) materials. Collagen has a molecular structure that is anisotropic, making it linearly birefringent. It can be stained with Picrosirius red dye to enhance its birefringence and visibility under polarized light. The appearance of type I collagen goes from red to yellow as the fiber diameter decreases, and this effect is associated with a decreased level of birefringence (Whittaker et al. 1994). This optical technique has been used for decades to assess the structure of collagenous tissues and has been combined with uniaxial mechanical testing of tissues such porcine heart valves (Hilbert et al. 1996). However, it is limited in that it provides only qualitative information of the spatial distribution and anisotropy of collagen.
The Relevance in Reproductive Success of Sperm Head Polarization (Birefringence)
Published in Nicolás Garrido, Rocio Rivera, A Practical Guide to Sperm Analysis, 2017
Andrea Garolla, Alberto Bottacin, Ilaria Cosci, Massimo Menegazzo, Carlo Foresta
In general, the traditional polarized light microscope differs from a standard transilluminating microscope in that it includes a polarizer and a compensator before the condenser and an analyzer behind the objective lens.
Mechanochemical preparation of triptolide-loaded self-micelle solid dispersion with enhanced oral bioavailability and improved anti-tumor activity
Published in Drug Delivery, 2022
Dabu Zhu, Qiuqin Zhang, Yifang Chen, Minghua Xie, Jianbo Li, Shen Yao, Ming Li, Zhao Lou, Yue Cai, Xuanrong Sun
PLM and SEM further testified this result. The micrographs of Na2GA, TP, Na2GA&TP-UM, and Na2GA&TP-BM obtained from polarized light microscopy are shown in Figure 1(C). Material in crystal state has obvious birefringence under polarized light microscope. From the images of TP, Na2GA&TP-UM, it could be found that there was a mass of crystalline materials, while the birefringence disappeared in Na2GA&TP-BM. The electron micrographs of samples were shown in Figure 1(B). It could be visually seen that TP was block solid and the Na2GA was in a spherical state. After 30-min grinding, the intact morphology of the TP and Na2GA particles was destroyed, forming fine and irregularly shaped particles. Grinding made the solid particles more uniform, which increased the surface area of the solid particles and got better wettability and dispersibility (Descamps & Willart, 2016).
Comparison of remineralization by fluoride varnishes with and without casein phosphopeptide amorphous calcium phosphate in primary teeth
Published in Acta Odontologica Scandinavica, 2019
Nehal Raid Salman, Magda ElTekeya, Niveen Bakry, Samia Soliman Omar, Maha El Tantawi
Using polarized light microscopy [24], longitudinal ground enamel sections of 15 µm thickness were examined to measure lesion depth. Polarized light microscope can show different birefringence. The minerals in enamel refract polarized light in rays with 2 different amplitudes and refractive indices related to two planes of transmission (birefringence). The positive birefringence refers to the ray with the smaller amplitude (the slower ray) and the negative birefringence refers to the ray with the bigger amplitude (the faster ray). Respectively, these can be seen as dark, brown color and bluish green color [24]. Normal enamel was identified through its prismless surface layer, a dark continuous ribbon over the surface with striae of Retzius and alternative Hunter-Shreger bands (Figure 1). Demineralized enamel showed different zones (deep to superficial); a translucent zone, a dark zone, body of lesion and surface zone with positive birefringence (dark color) and loss of striae of Retzius and Hunter-Shreger bands (Figure 2). Remineralized enamel showed negative birefringence (greenish blue color) in MI varnish group (Figure 3) and in Prevident varnish group (Figure 4). Photomicrographs were obtained using a digital camera to measure lesion depth through an eyepiece-graduated lens micrometer with magnification = ×40. The mean depth in micrometers (µm) was the average of three lines: one on each side of the lesion and a third one in the center [25]. Examiner consistency was checked by repeated measurement of 10 specimens and comparing the duplicates using paired t test where no significant difference was found between these values.
The clinical and pathological relevance of waxy casts in urine sediment
Published in Renal Failure, 2022
Damin Xu, Jingzi Li, Suxia Wang, Ying Tan, Ying Liu, Minghui Zhao
A phase contrast microscope (Nikon 80i) was used to observe cells, casts, and microorganisms. Polarized light microscopy was used to observe lipid and crystals. Cells were quantified as the number found in high power fields (HPF, 400×) and casts were in low power fields (LPF, 100×), respectively. Each sample was examined independently by two nephrologists blind and the average value was recorded.