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Scanning Electron Microscopic Observations (scanning + electron_microscopic_observation)
Selected AbstractsScanning electron microscopic observation of oil/wax/water/surfactant systemINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2005K. Ikuta We observed the internal structure of an oil/wax/water/surfactant system using a scanning electron microscope to investigate the relationship between its hardness and state of wax crystal. The molten wax (hydrogenated jojoba oil, ceresin, polyethylene wax, carnauba wax, or microcrystalline wax) was cast in a home-made spiral mold of aluminum foil for preparing the test specimen for SEM observation. In hydrogenated jojoba oil a fine frame-like crystal structure, the so-called ,card-house structure,' was observed but not in other waxes. The mixture of hydrogenated jojoba oil and water showed a few small droplets deposited on the roundish wax frame-like structure. On the other hand, waxes other than hydrogenated jojoba oil did not change their internal structure when they were mixed with water. This result suggested that hydrogenated jojoba oil showed uniquely high affinity for water. In the system of oil, water, surfactant, and various kinds of waxes, their crystal structure, hardness, and the shape of dispersed water particles were remarkably changed with the combination of waxes. In the system with ceresin and carnauba wax, the hardness measured by a card-tension meter was high, and the internal crystal structure was fine and amorphous. The water particle in the ceresin and carnauba wax system had a smaller diameter than that in the system containing hydrogenated jojoba oil. The system containing hydrogenated jojoba oil showed a card house-like wax crystal structure without high hardness. It was considered that the wax crystal structure played an important role in providing hardness and in contributing to the water distribution in the oil/wax/water/surfactant system. [source] Toughened Oxide Composites Based on Porous Alumina-Platelet InterphasesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2001Sang-Jin Lee A novel mechanism for debonding at a weak interphase in an all-oxide composite is introduced. This methodology involves the use of alumina platelets that have a diameter of 10,15 or 5,10 ,m and a thickness of 1 ,m. The platelets induce constrained sintering of the ceramic powder, which results in permanent porosity. For room-temperature properties, only minor additions (0,3 vol%) of matrix powder yield sufficiently weak debonding interphases. The platelets lie in random, three-dimensional orientations and provide a debonding mechanism that is independent of temperature, in chemically compatible matrixes. Laminated composites with two types of matrixes,mullite and alumina,have been fabricated with modified fibrous monoliths of alumina in a triple-layer "core/interphase/matrix" arrangement. In the laminated systems, the intimate mixing of strong versus tough microstructures has been tailored by alternating various matrix:interphase thickness ratios. Preliminary load,displacement curves clearly demonstrate characteristics of "graceful failure" and notable improvements in the work of fracture. Scanning electron microscopic observation of the crack paths confirms the viability of platelets for producing permanently porous, debondable interphases at elevated temperatures in air. [source] Development of olfactory epithelium in the human fetus: Scanning electron microscopic observationsCONGENITAL ANOMALIES, Issue 3 2009Mitsuhiro Kimura ABSTRACT Aims:, Human olfactory epithelium becomes functional at birth, but prenatal development remains unclear. In the present study, we aimed to clarify the development of human olfactory epithelium using scanning electron microscopy (SEM). Methods:, The development of human olfactory epithelium was observed in 24 externally normal fetuses, which were formalin-fixed and long-preserved, with a crown-rump length (CRL) of 102,336 mm (gestational week 14,38). The olfactory mucosa in the superior wall of the nasal septum near the choana were dissected and observed under SEM. We examined the number of olfactory vesicles per unit area, diameter of olfactory vesicles, and number and length of cilia on olfactory vesicles. Results:, At circa (ca) CRL 100 mm (ca 14 weeks), olfactory epithelium displayed several olfactory vesicles with 1,2 short cilia per unit area. At ca CRL 150 mm (ca 18 weeks), olfactory vesicles were present in small clusters, and cilia were longer. At CRL lager than 225 mm (ca 26 weeks), olfactory vesicles became located separately from each other, while length and number of cilia per olfactory vesicle were further increased. Conclusion:, The present findings suggest that fetal olfactory epithelium becomes morphologically almost the same as that in adults in late gestation, much later than previously thought. [source] Compatible blends of ethylene-vinyl acetate copolymer and hydrogenated nitrile rubberADVANCES IN POLYMER TECHNOLOGY, Issue 1 2004P. Thavamani Abstract The miscibility and some physico-mechanical characteristics of ethylene vinyl acetate (EVA) copolymer and hydrogenated nitrile rubber (HNBR) have been investigated using differential scanning calorimetry, dynamic mechanical and thermal analysis, and electrical conductivity. EVA was found to be miscible with HNBR at all properties. Infrared spectroscopic studies revealed that there is some chemical interaction between the constituent polymers. Scanning electron microscopic observations on the morphology of preferential solvent extracted samples indicated that in the blend the major constituent forms a continuous matrix in which the minor one is dispersed. At equal proportions, both EVA and HNBR exist as discontinuous phase. Variation of strength properties with blend composition is also discussed. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 5,17, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10066 [source] Age-related changes in the human thymus studied with scanning electron microscopyMICROSCOPY RESEARCH AND TECHNIQUE, Issue 8 2008Carlo Cavallotti Abstract This investigation describes some morphological, age-related changes in different compartments and cells of the human thymus. Scanning electron microscopic observations were done on human thymus samples obtained from four young and eight elderly patients during thoracic surgery and/or diagnostic biopsy of the thymus, after receiving authorization from the Ethical Committee of our university. The morphological data were submitted to quantitative image analysis so as to obtain quantitative results. Subsequently, the related values were used for statistical analysis. Our findings demonstrate that (1) all thymus compartments (subcapsular spaces, cortical, medullar, thymus microenvironment) contain numerous thymocytes even after the thymus has aged. (2) In older humans, residual thymus lymphoid islets contain, in addition to fatty cells and/or fibrous cells, also the same types of resident and nonresident cells (permanent and moving cells) that are found in young and adult subjects. (3) Endothelial cells of thymus microvessels contain numerous gaps. These gaps are tight in young subjects and become loose with age. (4) Thymocytes, in older subjects, are always found near these loose endothelial gaps of thymus microvessels. (5) While thymus cortical microvessels are provided with pericytes and/or periarteriolar spaces, microvessels of the thymus medullar are free of such spaces. Our morphological and quantitative results lead us to consider the possibility that the thymus fraction of resident and permanent cells (including thymocytes and reticular epithelial cells) is larger in younger subjects compared with older ones. The endothelial loose gaps of thymus microvessels, in older subjects, can allow the bidirectional transit of thymocytes through the wall of the said microvessels. Microsc. Res. Tech., 2008. © 2008 Wiley-Liss, Inc. [source] Effects of tebuconazole on morphology, structure, cell wall components and trichothecene production of Fusarium culmorum in vitroPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 6 2001Zhensheng Kang Abstract The effects of tebuconazole, a systemic fungicide, on the morphology, structure, cell wall components and toxin production of Fusarium culmorum were investigated in vitro. Treatment was by application of four filter paper strips (0.75,cm,×,5.0,cm) soaked in 20,µg,ml,,1 fungicide placed around a point inoculum in Petri dishes. Mycelial growth was strongly inhibited by fungicide treatment. Scanning electron microscopic observations showed that the fungicide caused irregular swelling and excessive branching of hyphae. The morphological changes induced by the fungicide at the ultrastructural level included considerable thickening of the hyphal cell walls, excessive septation, the formation of the incomplete septa, extensive vacuolisation, accumulation of lipid bodies and progressing necrosis or degeneration of the hyphal cytoplasm. Non-membrane inclusion bodies were often detected in the hyphal cytoplasm. Furthermore, the formation of new hyphae (daughter hyphae) inside collapsed hyphal cells was common following treatment. The daughter hyphae also displayed severe alterations such as irregular thickening of the cell walls and necrosis of the cytoplasm. Using cytochemical techniques, the labelling densities of chitin and ,-1,3-glucan in the cell walls of the fungicide-treated hyphae were more pronounced than in those of the control hyphae. Moreover, immunogold labelling with antiserum against deoxynivalenol (DON) revealed that Fusarium toxin DON was localized in the cell walls, cytoplasm, mitochondria and vacuoles of the hyphae from the control and the fungicide treatment, but the labelling density in the fungicide-treated hyphae decreased dramatically compared with the control hyphae, indicating that tebuconazole reduced Fusarium toxin production of the fungus. © 2001 Society of Chemical Industry [source] Saccharin Test of Maxillary Sinus Mucociliary Function After Endoscopic Sinus SurgeryTHE LARYNGOSCOPE, Issue 1 2000Kazuyasu Asai MD Abstract Objectives: To determine the usefulness of the saccharin time (ST) test for evaluating the mucociliary function of the maxillary sinus after endoscopic sinus surgery (ESS) for chronic sinusitis. Study Design: Methods: This study was conducted on 88 maxillary sinuses of 74 patients after ESS. The maxillary sinus fontanel was broadly opened via the middle meatus using an endoscope, and a saccharin granule was adhered to the bottom of the maxillary sinus mucosa. The time until the patient recognized the sweet taste was recorded. Before the ST test, the bilateral maxillary sinuses were classified into the following four groups on the basis of the post-ESS severity of mucosal edema and swelling as revealed by endoscopic observation: normal (45 sinuses), mild mucosal edema and swelling (24), moderate mucosal finding (14), and severe mucosal finding or filling of the sinus with a polyp(s) (5). Results: The mean ST values in the normal group and the groups with mild, moderate, and severe mucosal edema and swelling were 35.7, 38.1, 63.6, and 88.0 minutes, respectively. Thus the ST increased with the post-ESS severity of the mucosal lesion. However, for the group with mild mucosal edema and swelling, scanning electron microscopic observation of three maxillary sinuses in which the ST exceeded 120 minutes and four sinuses in which the ST was 40 minutes revealed extensive cilia loss in the former sinuses, but not in the latter. A second post-ESS endoscopic observation was performed in 17 patients, revealing improvement in 11 sinuses, no change in 5 sinuses, and aggravation in 1 sinus (compared with the initial test). The ST test was also repeated, revealing that the ST became shorter in most of the endoscopically improved sinus group. However, a few sinuses showed a discrepancy between the change in the endoscopic findings and the ciliary function (ST). Conclusion: Measurement of the maxillary sinus ST is a simple, accurate, and useful technique for assessing the post-ESS mucociliary function in conjunction with endoscopy, and the information gained can help in deciding subsequent therapy. [source] | |||||||||||||