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A polarized light microscope (PLM) was utilized to examine the optical textures of mesophase pitch (MP) and MP-derived fibers, which aimed to reveal the arrangement and orientation characteristics of pitch molecules and to clarify the evolution and transformation mechanism of carbonaceous microcrystalline from pitch fibers to graphitized fibers. The results found that there were distinct optical textures in MP, where one side exhibited a transition from a flattening plane to a mountain-like undulating plane. This transition corresponded to the arrangement of pitch molecules, resembling stacked lamellar structures reminiscent of curved paper. Meanwhile, the optical textures of fibers revealed that the blue substance was wrapped around the red grain-like domains in the longitudinal section and confirmed that the red part belonged to the pyridine insoluble fraction of MP and the blue part belonged to its pyridine-soluble fraction. After graphitization, the red part was transformed into graphite sheets and the blue part was transformed into an amorphous carbon layer which was wrapped around the graphite sheets, forming a carbonaceous microcrystalline package-like bag. Therefore, this study provided a comprehensive interpretation of the structural evolution mechanism of MP and MP-derived fibers based on their macro-optical textures and micro-nanostructures. [ABSTRACT FROM AUTHOR]

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• Temperature-dependent wax precipitation behavior of asphalt wax directly observed. • Microscope images were accurately processed to obtain wax precipitation parameters. • Wax precipitation indexes based on VT-PLM and novel viscosity method were compared. Wax precipitation and crystallization at low temperatures limits the use of wax warm mix additives in asphalt binders. In this study, variable-temperature polarized light microscopy (VT-PLM) was used to conduct in-situ observation and quantitative evaluation of the low-temperature precipitation of four waxes in asphalt binders. A novel DSR viscosity method was also used to test the wax precipitation temperatures (WPTs) of wax-doped asphalt binders. The results showed that different waxes exhibit different optical properties and shapes after low-temperature crystallization. There are plateau temperatures (about 20–30 °C) during the cooling process. Below the plateau temperatures, the tendency for crystallized waxes to continue growing are no longer obvious. In addition to an asphalt binder with 5 % F-T wax, the WPTs obtained by the novel viscosity method are significantly higher than those obtained by the VT-PLM method, indicating that the viscosity method is more sensitive. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are ubiquitous in the environment. However, it is unclear whether MPs are present in mammalian lungs through inhalation, and if so, could be possibly found in fetal tissues. In this study, we aim to determine the presence and characteristics of particles in domestic and fetal pig lung tissue in the natural environment. Specimens from the lungs of domestic pigs (n = 10) and fetal pigs that already died in matrix during vaginal birth from the non-contaminated area (n = 10) were obtained from farmers' nearby sludge treatment plant. These specimens were compressed between two glass microscope slides, which were examined under polarized light microscopy. In addition, Agilent 8700 LDIR Chemical imaging system (LDIR) was used to determine the quantitative and qualitative characteristics of MPs. According to the polarized light microscope survey of domestic pig lungs, we observed an average of 12 particles/g, which was more than the 6 particles/g observed in fetal pig lungs, which ranged in size from 115.14 μm to 1370.43 μm. All the observed MP particles were fiber in shape. LDIR indicated an average of 180 particles/g of domestic pig lungs, ranging in size from 20.34 μm to 916.36 μm, which was twice as many MPs observed in fetal pig lungs. Furthermore, the compositions of MPs were different between them. LDIR indicated that polyamide (PA) was the most common polymer identified in domestic pig lungs (46.11%), while polycarbonate (PC) was the most common polymer in fetal pig lungs (32.99%). These findings confirmed the presence of MPs in the lung tissue of both domestic and fetal pigs in the natural environment, but the main characteristics differed. This fact indicated the increasing risk of MPs to human respiratory tract is increasing. Further research should be conducted to entirely estimate the specific exposure level on humans and offspring. • Microplastics present in the lungs of domestic and fetal pigs in the natural environment. • The fiber was the most common shape of identified microplastics in the lung tissue. • The major component of microplastics differed between domestic and fetal pigs. [ABSTRACT FROM AUTHOR]

lntracytoplasmic sperm injection (ICSI) is traditionally performed with the first polar body at 6 or 12 o'clock, and the injection pipette inserted at 3 or 9 o'clock. This positioning aims to direct the path of the injection pipette at a distance from the presumed metaphase 11 spindle position. Since spindles can now be imaged directly in living oocytes using computer-assisted polarized light microscopy, the effectiveness of this positioning precaution was studied. Patients undergoing oocyte collection and ICSI had their oocytes non-invasively imaged for spindles prior to ICSI. The spindle position relative to the first polar body at 6 o'clock was assessed using an analogue clock face as an approximation. Fertilization and embryo quality were recorded blind to spindle position. Polar body displacement and spindle position at ICSI did not significantly affect fertilization or embryonic quality. The highest frequency of normally fertilized oocytes and good quality embryos developed from oocytes with spindles located in or near the plane of injection at ICSI (the 3, 4, 8 and 9 o'clock positions). This study questions the usefulness of spindle imaging and the relevance of positioning the first polar body at 6 o'clock during ICSI. [ABSTRACT FROM AUTHOR]